Issue 3165. 17 February 2018 New Scientist

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FLOWERY LANGUAGE

Why plants are struggling to get their message across

WRONG KIND OF SAND

We’re running out of the stuff that built civilisation

THE THUNDERDRONE

Flying robot wars test anti-drone defences

WEEKLY 17 February 2018

OLD FRIEND Stone-Age people kept dogs as pets

WHEN THE FUTURE COMES BEFORE THE PAST The quantum twist that breaks the rules of reality

No3165 £4.50 US/CAN$6.99

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PLUS DARK MATTER QUARKS/URBAN EVOLUTION/VAPE CRUSADERS/HUNTING WHALES/ SANITISER SUPERBUG/CLASSIC EXPERIMENTS/FACE-RECOGNITION SPECS/ROCKETS AWAY!

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CONTENTS

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Volume 237 No 3165

Analysis Cape Town is running out of water 20

On the cover

Leader

32 Flowery language Why plants are struggling to get their message across 35 Wrong kind of sand We’re running out of the stuff that built civilisation 4

The thunderdrone Flying robot wars test anti-drone defences

10 Old friend Stone-Age people kept dogs as pets 28 When the future comes before the past The quantum twist that breaks the rules of reality Plus Dark matter quarks (8). Urban evolution (45). Vape crusaders (23). Hunting whales (26). Sanitiser superbug (7). Classic experiments (41). Face-recognition specs (13). Rockets away! (14)

3

Revisiting ethically dubious experiments of the past. We need to rethink our exploitation of sand

News 4

THIS WEEK Drones vs drones. Antarctic mission. NASA telescope at risk. Opioids in the UK

6

NEWS & TECHNOLOGY How should we deflect a deadly asteroid? Trauma nurse ants. Superbug resists hand sanitisers. Australia’s forgotten megastorms. Twisted space-time and dark matter. Extinction by sterilisation. Our ancient soft spot for dogs. Online chat gives cyberattack warnings. Gene activity shapes mental health. Smart glasses fight crime. SpaceX kicks off new era of space flight. Human eggs matured in lab for first time

17 IN BRIEF Houdini beetles. Weird ice. The first portable atomic clock. Parents nurse premature babies

Analysis 20 Cape Town As the South African city runs out of water, how did things get this bad? 22 COMMENT A quantum computer revolution nears. Labels should say if your meat met a better end 23 INSIGHT It’s time to take vaping seriously as a way to save lives

Features 28 Blast from the future The quantum twist that breaks the rules of reality 32 Silence of the plants The fragrant language of plants is being destroyed by human activity 35 Sand storm We are running out of the stuff that built civilisation 41 Real-life Lord of the Flies How Muzafer Sherif’s schoolboy experiment led us astray

Culture 44 Inside story of blood The discoverer of our circulation deserves his own exhibition 45 Wildlife to street life Nature can inhabit the city, but only if we help 46 The cat in the ceiling Absurdity shapes a show on data and culture

Regulars 26 APERTURE Hunting whale blows bubbles 52 LETTERS Everything put together falls apart 55 SIGNAL BOOST Offset the carbon from trips 56 FEEDBACK Robot priests 57 THE LAST WORD Sting in the tail

17 February 2018 | NewScientist | 1

DEFINITION of “Gorilla” A company that dominates an industry without having a complete monopoly.” Investopedia.

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Refighting old battles Are ethically dubious experiments from the past ever fair game? “THE past is a foreign country, they do things differently there.” That aphorism is as true for science as for any other walk of life. Experiments done in the past sometimes couldn’t be repeated today, which makes them a treasure trove of valuable information – albeit not one that should be opened casually. Consider a classic experiment that we revisit this week (see page 41). It involved two groups of boys let loose in the wilds of Oklahoma to test their capacity for intergroup rivalry. If somebody proposed doing the same today, it wouldn’t get past the ethics committee. And yet the questions

it set out to answer are as relevant now as they were back then. The Robbers Cave experiment was staged during a time of political tumult not dissimilar to today’s. The experimenter was a Turkish immigrant who felt increasingly unwelcome in the US. The central question of his study concerned human nature: are we inherently tribal, or do social conditions drive us to become so? The contemporary relevance of the experiment is impossible to miss. There are, of course, problems with disinterring old research results. Ethicists have long agonised about the use of data

Heads out of the sand THERE is something absurd about the idea that the world is running out of sand, but the reality on the ground – or under it – is no laughing matter. Despite some 10 per cent of Earth’s surface being covered with sand, most of it is useless to us (see page 35). Getting at the right sort is causing terrible environmental degradation. If that sounds like one more

thing to be guilty about, well, sorry – it is. Just as your demand for plastic contributes a small amount to ocean pollution and your use of transport and electricity allow carbon dioxide to leak into the atmosphere, your need for concrete helps to drive the destructiveness of sand mining. That is the reality of living in the Anthropocene:

gathered by Nazi doctors. Murderous as they were, some of these experiments produced data that could save lives today. Should the information ever be used? Nobody is suggesting that Robbers Cave is in the same ballpark, but it is still worth asking whether the work should be seen as valid. On balance, the fact that it didn’t do any lasting harm to anybody suggests it is fair game. Indeed, we hope that retelling and reinterpreting classic experiments through contemporary eyes will become a regular feature in New Scientist. A visit to a foreign country can often tell us much about our own. ■

individual impacts may be small, but our collective footprint is so large that we are affecting Earth’s geology, atmosphere and climate. Admittedly, cutting out concrete is harder than offsetting your flights or reducing your consumption of plastic bags. But that makes sand a useful rallying cry for top-down action. There is little more potent symbol of our destructiveness than the fact that we are running out of something so apparently limitless. ■ 17 February 2018 | NewScientist | 3

THIS WEEK

Clash of the drones A competition to take out rogue drones has some innovative entries Timothy Revell

country’s Ministry of Justice and Security sponsored a competition designed to test out the tech required to take out a rogue drone. Dubbed the “anti-drone” competition, the aim of DroneClash was to home in on a reliable way to pluck illegal or unwanted drones out of the sky. The organisers put up a $30,000 prize for the best idea.

DRONES are wreaking havoc. Last year, London’s Gatwick Airport had to divert flights when a drone was spotted flying nearby. In the UK, there were more than 100 incidents involving drones close to airports in 2017 – the most ever, and other countries have seen similar increases. Reports of near misses are at an all-time high. So authorities are eager to find “Tactics include spaghetti, string to foul propellers, ways to bring down drones safely and reliably. But the task is harder firing darts at other drones and even an airgun” than you might think. “Most options to either catch a drone in the sky or drive it out In DroneClash, the teams each of the area are experimental had to defend a “queen drone” or cause too much collateral and use “attack drones” to battle damage,” says Mark Wiebes, their opponents. To reach the Innovations Manager at the Dutch queens, the attackers had to travel National Police. “Geo-fencing” is through the Hallway of Doom one option but even that is not Death and Destruction, which foolproof and relies on users and included a variety of countermanufacturers playing along drone measures such as bright (see “Bird in the hand”, right). lights, smoke and a net launcher. That’s why Dutch police and the “DroneClash is like Robot Wars

in the air,” says Bart Remes at the Delft University of Technology in the Netherlands, one of the competition’s organisers. Teams could score points for taking down other drones, but maximum points were awarded for stopping drones, grabbing them and safely placing them in a nearby box. There were several knock-out rounds before the winner-takes-it-all finale. Speaking before the event, William “IN-YOUR-FACE!” Thielicke, from team DiPol, described a cunning plan to use raw spaghetti, which he hoped would give his team the edge. As a defence mechanism, their queen was to have pieces of pasta, reinforced with cord around the strands and pointing in every direction, so that any drone flying near it risked a broken propeller. Dipol’s attack drones would also have a couple of pieces of spaghetti attached like a lance. “We will then crash into the other

drones as quickly as possible,” says Thielicke – hopefully, taking out the competition in the process. A simpler approach was planned by the Laced Horns team, from the University of Twente in the Netherlands and Clear Flight Solutions, a firm known for building flying robotic birds. The team’s approach was to make very robust attack drones with a frame extending all the way round the propellers, reinforced with carbon plates. To destroy the competition, they simply bash into them. “It relies on pilot skill,” says Geert Folkertsma, one of the team. Other tactics include dangling a piece of string above a drone to tangle up the propellers so it falls out of the sky, firing darts at the opposition, and even an airgun to throw the target off-balance. “In a practice session, there was a draft in the room that made the drone fly like crazy, we just couldn’t control it, so we’re trying to reproduce that,” says Daniel

Exploring a oncehidden world

covers 5800 square kilometres. “It’s

MARIO TAMA/GETTY

AN EXPEDITION to an unexplored, newly revealed Antarctic ecosystem began this week. An international team set off to study a mysterious area of the ocean that has been concealed for thousands of years. The ecosystem was hidden under the Larsen C ice shelf for 120,000 years. It was exposed when a huge iceberg calved off in July last year. The iceberg, known as A68, is four times the size of London, and weighs in at around 1 trillion tonnes. It is one of the largest ever recorded. Katrin Linse of the British Antarctic Survey, who is leading the expedition, says she wants to investigate the marine life on the seabed, which 4 | NewScientist | 17 February 2018

important we get there quickly, before the undersea environment changes as sunlight enters the water and new species begin to colonise,” she says. The team plans to collect animals, microbes and plankton, as well as samples of water and sediments, and will record the movements of marine mammals and birds into the area.

Trump to NASA: cuts are coming ONE of NASA’s planned space telescopes is on the chopping block. President Trump has released his 2019 budget request, and despite an overall rise of $370 million on its 2018 funding, NASA is facing potential cuts.

For new stories every day, visit newscientist.com/news

ANDREW TESTA/THE NEW YORK TIMES/REDUX/EYEVINE

BIRD IN THE HAND

In for the kill: trained eagles can catch drones... if they want to–

Vernis from a team called The Wand, who have developed a form of airgun. As New Scientist went to press the battle was just getting under way in a Dutch aircraft hangar near Leiden. Many teams were also keeping their strategies secret, but some had developed methods for safely plucking drones out of the air in

Among those are five Earth science missions and the Wide Field Infrared Survey Telescope planned to launch in the mid-2020s. WFIRST is intended to hunt for the effects of dark matter and dark energy, and would also have instruments to find exoplanets. A review found that WFIRST would exceed its original $2 billion budget. It has been competing for cash with the planet-hunting James Webb Space Telescope. “Developing another large space telescope immediately after completing the $8.8 billion James Webb Space Telescope is not a priority for the Administration,” the budget request said. This proposal also includes plans to end NASA funding for the International Space Station in 2025, with a possibility of handing over its operation to commercial firms.

an attempt to get the maximum number of points, says Remes. Although the event was designed to be fun, DroneClash has a more serious side. Drones have also been used to deliver contraband to people in prisons, as well as in an attempt to bomb a Russian airbase in Syria. “I know of one incidence where an ambulance helicopter couldn’t land because of a drone flying,” says Wiebes. “These are

Poorer people and prescription opioids DOCTORS in England have been prescribing opioid painkillers disproportionately to people in the least affluent parts of the nation. An analysis of nearly three years of prescribing data up to February 2014 found that northern England contained 9 out of 10 of the regions where eight opioid painkillers were most frequently prescribed (British Journal of General Practice, DOI: 10.3399/bjgp18X695057). Many of these regions fall in socially deprived areas. From earlier research we know that 40 per cent of men and 44 per cent of women in the poorest quarter of England’s population experience chronic pain.

really serious incidents.” A UK Department of Transport study last year showed that even a small drone may damage a helicopter’s rotors or a plane’s windshield. “We are a firm believer in drones and how they will improve society,” says Remes. “But there also need to be no go zones where we can take measures against drones for public safety.” ■ Check newscientist.com for details of the competition winner

In the US, the opioid crisis has already reached epidemic levels. Last week, Congress adopted a budget that includes $1.5 billion spread over the next decade to help families with babies born addicted to opioids. Purdue Pharmaceuticals, which sells the painkiller OxyContin, said last week that it will no longer actively market opioids to doctors.

Face recognition’s biases on show FACE-recognition software can guess your gender with amazing accuracy – if you are a white man. Joy Buolamwini at the Massachusetts Institute of Technology tested three commercially available

Anti-drone measures aren’t new, but few are very successful. Eagles trained by the Dutch police to pluck drones out of the sky and bring them back to base with their big talons looked promising for a while. Unfortunately, eagles don’t like being told what to do. The project was scrapped over concerns that the birds might go after food instead of the intended target. The US Air Force is trying to find out if falcons are up to the task. Another approach is to use a radio jammer in a particular area, so-called geo-fencing, so that the instructions from the pilot won’t be received. This could be effective in some instances, but may not work on drones that can fly autonomously. The US military has previously released footage of a microwave gun that essentially fries a drone’s electronics. Though the approach could work on the battlefield, a drone falling in a civilian area could create a lot of trouble. Employing a laser gun creates similar problems. What’s needed is some new ideas, and a big drone battle could be the way to generate inspiration (see main story).

face-recognition systems, created by Microsoft, IBM and the Chinese company Megvii. The systems correctly identified the gender of white men 99 per cent of the time. But the error rate rose for people with darker skin, reaching nearly 35 per cent for women. Face-recognition software is already being used in many different situations, including by police to identify suspects in a crowd (see page 13) and to automatically tag photos. This means inaccuracies could have consequences, such as systematically ingraining biases in police stop and searches. Biases in artificial intelligence systems tend to come from biases in the data they are trained on. According to one study, a widely used data set is around 75 per cent male and more than 80 per cent white. 17 February 2018 | NewScientist | 5

NEWS & TECHNOLOGY

Deflector Selector says nuke asteroids six million hypothetical objects with the potential to hit Earth. Next, they looked at how early each could be detected before collision, and the velocity change needed to knock it off course. Finally, they looked at which of three technologies would be best at doing this: nuclear weapons, kinetic impactors or gravity tractors.

IF AN asteroid was set to hit Earth, humanity would have to scramble to conduct the world’s riskiest experiment. We have never tried to shove a space rock off its course, so any defence effort would be a shot in the dark. People have come up with ideas – like chucking nuclear weapons at an incoming threat – but with limited asteroid defence budgets, which should we pursue? An algorithm called the Deflector Selector says nukes would do the job about half the time. To be clear, Erika Nesvold, formerly at the Carnegie Institution for Science in Washington DC, and her team don’t suggest we give a computer free reign over nuclear missiles. “We are absolutely not advocating putting the algorithm in charge of asteroid defence,” she says. Instead, their machine learning algorithm can study a population of potentially hazardous objects, and determine which technology has the best chance of deflecting them from Earth’s path. To build the algorithm, Nesvold and her colleagues simulated

Ants nurse each other back to health A SPECIES of ant has become the first known non-human animal to treat the injuries of its fellows. “Nurse” ants lick the lacerations of fallen comrades, and this helps them to survive. Matabele ants (Megaponera analis) live dangerous lives. Several times a day, parties of soldier ants set out to hunt termites, dragging them from their nests and carrying them home. 6 | NewScientist | 17 February 2018

What could we do if an asteroid was on a collision course with Earth?

DETLEV VAN RAVENSWAAY/SCIENCE PHOTO LIBRARY

Jacob Aron

Nuclear weapons release an explosive force, while a kinetic impactor is essentially like trying to shoot one bullet out of the air with a much smaller one. Gravity tractors are more subtle. The idea here is to put a spacecraft near an asteroid, and let its gravitational pull slowly tug the rock off course, but the concept hasn’t been tested. All this number crunching required a cluster of 100 computer cores running for around 40 hours. To bring the timing down, the researchers turned

The termites fight back, and their powerful jaws can administer lethal bites. The ants often lose limbs. In 2017, Erik Frank, then at the University of Würzburg, Germany, reported that Matabele ants routinely carry their wounded back to the nest. This is odd: social insects usually treat each other as expendable. Injured ants “asked” for help by releasing a pheromone, prompting other ants to carry them. In a follow-up, Frank, now at the University of Lausanne in Switzerland, and his colleagues have filmed what happens in the nest when the injured

are brought in. The footage shows nurse ants spend several minutes licking their fellow ants’ wounds. Without this attention, 80 per cent of ants who had lost limbs died within a few hours. Of those that received care, 90 per cent survived (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2017.2457). “We don’t know yet if the ants are just cleaning the wound and removing

“The ants were selective in who they picked up. They didn’t want to help ants that had lost five legs”

to machine learning. Using the simulation as training data, they taught an algorithm to study a given population of objects and decide which tech had the best chance of deflection. Nesvold says after the algorithm is trained, it can supply an answer in seconds instead of hours. The team tried their trained algorithm on three populations: hazardous near-Earth asteroids, comets and rubble piles – loose collections of material, rather than solid objects. In each case, nuclear weapons could tackle about 50 per cent of the objects. Kinetic impactors and gravity tractors had lower success rates (arxiv.org/abs/1802.00458). That might suggest we should invest in nuclear weapons as our asteroid defence of choice, but there are issues when it comes to mounting these on rockets. “The risks created by pursuing a nuclear asteroid defence programme would far outweigh the actual risks posed by asteroid impacts,” says Eric Christensen at the Catalina Sky Survey. The gravity tractor success rates improved when the asteroids were spotted earlier. “That points to the need for better asteroid monitoring and detection surveys,” says Nesvold. “Earlier detection of potential impactors will provide more lead time to plan and execute a mission,” agrees Christensen. ■

debris, as we do with our wounds to prevent infection, or if they are also applying antimicrobial substances with their saliva,” says Frank. Either way, the treatment works. “The ants are able to reach running speeds similar to healthy ants, despite missing a leg or two,” says Frank. The ants probably don’t feel compassion, says Frank, but want to keep their numbers up. Indeed, not all the soldiers were rescued. “The ants were selective in who they picked up,” says Frank. “They didn’t want to help heavily injured ants who had lost five legs.” Jasmin Fox-Skelly ■

For daily news stories, visit newscientist.com/news

A DANGEROUS strain of bacteria has found a way to resist hand sanitisers. These alcohol-based sanitisers were introduced to many hospitals in the early 2000s to fight the spread of drug-resistant superbugs like MRSA and vancomycin-resistant Enterococcus (VRE). Although the bacteria had evolved resistance to antibiotics, it was assumed they wouldn’t be able to do the same for alcohol, which kills them much faster. Since the introduction of hand sanitisers, hospital MRSA rates have sharply declined. But VRE rates have increased fivefold in some places, with more than half of those infected dying. Now research by Timothy Stinear at the University of Melbourne and Lindsay Grayson at Austin Hospital, both in Australia, suggests that VRE bacteria have developed alcohol tolerance. The pair used paper wipes soaked in alcohol-based hand sanitiser to disinfect mouse cages that had been coated with VRE samples collected in either 1998 or 2012. Based on how many mice became infected, they concluded that alcohol was 35 per cent less effective at killing the 2012 VRE bacteria than the earlier strain. When they studied 139 samples collected from Melbourne hospitals between 1998 and 2015, they found that the more recent bacteria were 10 times as tolerant to alcohol than the older ones (bioRxiv, doi.org/ckdt). This seemed to correspond with changes in the bacteria’s alcoholprocessing genes, which may have made their outer cell membranes more impervious to alcohol. Rather than showing that hand gels don’t work against VRE, the findings may mean that healthcare workers aren’t using them properly, says Grayson. If they sometimes forget to use them or use gel and foam formulations with lower alcohol contents, superbugs have a better chance of surviving and evolving tolerance, he says. Alice Klein ■

TORSTEN BLACKWOOD/AFP/GETTY IMAGES

Superbug fights back against hand sanitisers

Predicting megastorms from 1800s ships’ logs “IT WAS blowing a perfect They collected temperature and hurricane… the sea at this time pressure data from a handful of running mountains high…” weather stations that have records That was one of the last things back to the 1850s. They also written in the logbook of a ship studied coastal erosion to see called the Catherine Hill, before when storm damage occurred. a storm drove it aground north of Where possible, they crossSydney, Australia, on 21 June 1867. checked this with ship logbook Storms like it are being studied to extracts and weather reports help weather forecasters predict from the Sydney Morning Herald future recurrences. newspaper from 1831 onwards. Australia’s east coast is lashed This helped them reconstruct by huge storms called “extreme some of Australia’s worst storms. east coast lows” every 10 to 20 The most famous was on 20 years. Their rarity makes them August 1857 and sank the Dunbar hard to predict. Meteorologists did not foresee the severity of the “The decks burst up from the pressure of the water 8 June 2007 storm, for example, and the ship was rent in which a coal ship ran aground. into a thousand pieces” “Most forecasters would only see one such event during their careers, and nobody working on just outside Sydney, killing more the forecast desk at the time had than 120 people. One newspaper ever seen anything like it,” says account described how “the decks Stuart Browning at Macquarie burst up from the pressure of the University in Sydney. water, the ship was rent into a Most of what we know about thousand pieces, and all on these storms is based on satellite board… were hurried into the data, which only goes back to 1979. foaming and terrific sea”. Browning and his colleague Browning and Goodwin found Ian Goodwin have now pieced that severe storms are most likely together information stretching when two climate cycles line up: back almost two centuries. the El Niño Southern Oscillation

A storm forced the Pasha Bulker aground in 2007–

(ENSO) and the Interdecadal Pacific Oscillation (IPO). Both affect sea surface temperatures. Conditions are most ripe when the ENSO is in its La Niña phase and the IPO goes from a positive to negative phase. La Niñas warm the sea surface around Australia, and are stronger and more frequent during negative IPO phases. When the warm sea air hits cold air on land, the resulting storms can be intense “weather bombs”, says Browning. Rising air releases moisture as rain, as well as lots of energy, causing strong winds and ocean waves up to 18 metres high. Browning presented the data last week at a meeting of the Australian Meteorological and Oceanographic Society in Sydney. He and Goodwin plan to refine their predictions using weather observations from old ship logbooks. Petra Pearce at the National Institute of Water and Atmospheric Research in New Zealand has digitised more than 130,000 logbook images from the 18th century onwards. She also presented at the meeting. Fortunately, Browning says such storms are unlikely this decade, as the IPO is moving into its safer positive phase. Alice Klein ■ 17 February 2018 | NewScientist | 7

NEWS & TECHNOLOGY

Anil Ananthaswamy

SOLVING the case of the universe’s missing antimatter may help us pin down one other thing we can’t seem to find: dark matter. The solution involves a twist in the tale of gravitational waves. Matter and antimatter should have been produced in equal amounts after the big bang. But antimatter is nowhere to be found. Physicists think that primordial processes made a tiny excess of matter over antimatter. When matter meets antimatter, it annihilates. The leftover excess of matter would can be seen in the stars and galaxies. But how did the mismatch come about? One previous answer involved neutrinos, which have a property called chirality – the way they twist, or their handedness. In principle, particles can be either left-handed or right-handed, but neutrinos are only left-handed. Evan McDonough of Brown University in Providence, Rhode Island, investigated what would happen if this chiral asymmetry wasn’t limited to particles. He found that if the infant universe had gravitational waves – ripples

Was the Great Dying the Great Sterilisation? WE MAY have misunderstood the worst ever extinction. The Permian die-off has been blamed on volcanic eruptions, but instead of killing, the eruptions may have had an insidious effect: sterilisation. Organisms may not have died, but if they could not reproduce, their species were doomed. Scientists have long debated the cause of an event 252 million years 8 | NewScientist | 17 February 2018

in the fabric of space-time – with a preferred chirality, that could also create an excess of matter. That led him, with Stephon Alexander at Brown University and David Spergel at Princeton University, to wonder whether the same mechanism could account for dark matter, the unseen mass we detect via its gravitational influence on normal matter. For decades, physicists have thought that dark matter is made of something called weakly interacting massive particles (WIMPs). But all searches for WIMPs have so far come to nought. To get at dark matter another way, the team built a model in which the primordial universe had particles called dark matter quarks, which differ from the dark matter that is around today. If these particles had neutrinolike chirality, they would interact with the chiral gravitational waves to produce the kind of dark matter in the current universe (arxiv.org/abs/1801.07255). “It’s a cool idea,” says Michael Peskin at Stanford University in Palo Alto, California. “Anything you can do that

ago, at the end of the Permian period, during which most complex life died. Some years ago, geologists noticed something odd about pollen from the time. Many of the pollen grains were malformed or underdeveloped. That might be because volcanic activity spewed ozone-destroying chemicals into the air, so more of the sun’s harmful ultraviolet-B (UV-B) radiation reached Earth’s surface. The UV-B may have harmed plants like conifers and seed ferns. To mimic this, Jeffrey Benca and his colleagues at the University of California, Berkeley, exposed 18 dwarf conifers

NICOLLE R. FULLER/SCIENCE PHOTO LIBRARY

Dark matter born in cosmic twists

brings in a new idea into this area, it opens a door.” Just like matter and antimatter, you get an asymmetry between dark quarks and anti dark quarks, and eventually the universe is left with a small excess of dark quarks. As the cosmos cools down, they condense into a weird state of matter called a superfluid. This would form a background field that would still exist now, and excitations of this field would be akin to today’s dark matter particles. These would be much lighter than WIMPs and would not interact with normal matter. “It’s much wimpier than WIMPs,” says Spergel. Given that, it won’t be possible to look for these particles directly. But they will behave differently to

Gravitational waves that have handedness twist up space-time

to elevated UV-B levels for 56 days. As expected, the trees made more malformed pollen. But something else happened. The trees survived the UV-B, but all were infertile during the exposure period. Although the pines made seed cones, these quickly died (Science Advances, doi.org/ckdh). This was even true of cones shaded from direct exposure. “As long as just part of the tree is exposed to the

radiation, it’s not going to be happy enough to reproduce,” says Benca. This suggests a new story. Perhaps the volcanic activity didn’t directly kill many organisms. Instead, the UV-B may have sterilised most land plants. There seem to have been pulses of volcanic activity over millennia, so this may have happened over and over. “I think their conclusions are really robust,” says Jennifer McElwain at Trinity College Dublin in Ireland. However, the idea cannot explain the marine die-offs, says Richard Twitchett at the Natural History Museum in London. Colin Barras ■

“As long as part of the tree is exposed to the radiation, it’s not going to be happy enough to reproduce”

WIMPs on cosmological scales. For example, such dark matter would be distributed more evenly throughout a galaxy than WIMPs, without clustering on small scales. Also, the ratio of dark matter to normal matter may not be constant through the cosmos. These characteristics could give us a way to spot this kind of dark matter, Spergel says. For example, the uniform distribution would create a tell-tale signature in the cosmic microwave background, which is the radiation leftover from the big bang, or influence the formation of large-scale structures like clusters of galaxies. ■

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Ancient humans loved their dogs Colin Barras

guarded settlements or were used as pack animals for transport. However, Janssens and his colleagues say there is an alternative: we domesticated dogs simply because we liked having them as pets. Their reanalysis of the dog reveals it had terrible oral health. Although only about 7 months old when it died, the dog had

HOW long have we had a soft spot for dogs? A reanalysis of a prehistoric dog that was buried with two people reveals that the animal had experienced several bouts of potentially lethal illness. The fact it survived them suggests its owners cared for their dog as a pet. The Bonn-Oberkassel dog “The probability that was unearthed a century ago in the sick animal would Germany. It was buried alongside survive without human the remains of a man in his help is very, very low” 40s and a woman in her 20s. All are about 14,200 years old. The animal probably lived long experienced three periods of severe illness when it was between 19 and after dogs were domesticated, 23 weeks old, possibly due to a virus as evidence for this process that causes canine distemper stretches back at least 32,000 (Journal of Archaeological years. But the Bonn-Oberkassel dog is still a key specimen because Science, doi.org/ckcq). “The first infection would be it is the oldest known dog burial, enough to be lethal to most dogs says Luc Janssens at Ghent in the wild,” says Janssens. “Then University in Belgium. That came two extra bouts, and the means it can help us understand probability that the animal would why dogs were domesticated. survive without human help is A common assumption is that prehistoric humans domesticated very, very low.” The researchers argue that dogs to put them to work. Maybe the first dogs helped with hunting, the sick puppy would have been 10 | NewScientist | 17 February 2018

unable to do any useful work. In fact, keeping it alive was probably an unpleasant burden on its owners: it might have vomited regularly and had diarrhoea. Its survival hints that its owners felt a bond of friendship, just like a modern dog owner. “This is the first time we find [evidence] to suggest that dogs were treated emotionally, without expectation of any benefit,” says Janssens. Bonds of friendship may have helped drive domestication, says Mietje Germonpré at the Royal Belgian Institute of Natural Sciences in Brussels. “Wolf pups could have been ‘adopted’ to provide company,” she says. “This raising of wolf pups as pets could have been a stepping stone, together with other motives, on the pathway to the domestication of the dog.” It is significant that the dog was buried, says Pat Shipman at Pennsylvania State University. “When you start burying animals, it indicates a special relationship of some kind.” Nevertheless, Shipman says we can’t rule out the possibility that the Bonn-Oberkassel dog was – or could have become – a useful working dog. That might explain why its owners cared for it through its illness, in the hope that it would recover. ■

LIKE canaries in a coal mine, social networks can be used as early-warning systems for incoming cyberattacks. By monitoring online discussions for chatter about imminent threats, it is possible to predict attacks, including ones like last year’s WannaCry and NotPetya ransomware outbreaks, before they happen, giving potential targets a valuable heads-up. “In the last few years, cyberattacks have grown in number, diversity and impact,” says Anna Sapienza at the University of Southern California. But this also means that discussions about such attacks have become more frequent and visible. Sapienza and her colleagues at USC and Arizona State University built a tool that monitors the social media activity of prominent security researchers and hackers, as well as blogs and other online forums. It scans for posts about cybersecurity topics such as software vulnerabilities or malware, using text-mining software to pick out relevant keywords. The team found that in the days before an attack, there was often a spike in cybersecurity talk online. This reflects the team’s assumption that those behind an attack typically don’t operate in a bubble. They interact with others to identify weaknesses in a targeted system, obtain the tools needed to exploit them and recruit participants. These activities may get noticed and discussed elsewhere. When the tool detects an increase in relevant chatter, it automatically raises the alarm. In live tests between September 2016 and January 2017, the tool generated 661 alerts. Around 84 per cent of these flagged current or imminent cyberthreats. Retrospectively using data, the team also showed that its system would have generated alerts for WannaCry and NotPetya, both of which caused massive disruption around the world (arxiv.org/ abs/1801.09781). Douglas Heaven ■

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How genes shape our mental health the University of California, Los Angeles, and his team have been working out how active different genes were in the brain cells of tissue donated by people who had schizophrenia, bipolar disorder, depression, alcoholism or autism-like conditions when

A RANGE of mental health conditions seem to have overlapping effects on the brain. Analysing the gene activity behind this is helping us understand what causes schizophrenia and other disorders. Unlike cancer or heart disease, say, for which underlying biological causes have been identified, psychiatric disorders and some developmental conditions are defined by behavioural symptoms. We know that people born with certain gene variants can be more likely to develop schizophrenia, bipolar disorder and autism-like behaviour, but we don’t know what these genes might be doing, and how they put people at risk. “The brain is an incredibly complex organ – if something is out of whack, something else can step in to compensate, so it’s very difficult to identify the fundamental problem,” says Jehannine Austin at Canada’s University of British Columbia. Now it seems that the way some brain cells work is changed in similar ways in these conditions. Daniel Geschwind at

Police catch criminals with smart glasses SMART glasses have found a new use: fighting crime. In the past two months, seven fugitives and 26 people travelling with fake ID have been apprehended by police at Zhengzhou train station in China thanks to glasses with built-in face recognition. According to local media, some were wanted for alleged involvement in human trafficking.

Genes affecting astrocytes (blue) are more active in schizophrenia

DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY

Jessica Hamzelou

they died. “We found substantial overlap,” says Geschwind. The greatest overlap was seen between samples taken from people with bipolar disorder, schizophrenia and autism. These conditions also overlapped to a smaller degree with depression (Science, doi.org/ckd5). This mirrors what doctors have spotted across generations of families, says Austin. “We tend

The firm that developed the GLXSS Pro smart glasses, LLVision, says the face recognition feature is 99.4 per cent accurate. If a match can’t be found then the officer can send a photo to be checked against a central database. The glasses are very light so the police officers can wear them all day, says Zhang Xin at LLVision. Police in three Chinese provinces – Henan, Shandong and Xinjiang – are using the technology. Some highway patrol officers are doing so when they check drivers’ licences, for instance. It can also be used for

licence plate recognition. There are reports that police in Abu Dhabi will soon use smart glasses to help identify people suspected of a crime. US police departments have undertaken trials in the past, says George Jijiashvili at CCS Insight, a technology consultancy firm. Though there may be some resistance among the public, he says it is likely that US and European police

“While the technology may make it easier to solve crime, it could also be used to intimidate protesters”

to see disorders like depression, anxiety and bipolar disorder all in the same family,” she says. The new analysis reveals why some of these conditions overlap. In the brain, star-shaped cells called astrocytes help neurons grow. In people with autism, schizophrenia and bipolar disorder, genes involved in controlling how these astrocytes function seem to be more active. Each condition also had unique elements. Brain samples from people with depression, for example, showed signs of stress and inflammation. This chimes with growing evidence that brain inflammation plays a role in mood disorders, and that anti-inflammatory medicines might help treat depression. Heather Whalley at the University of Edinburgh, UK, hopes studies like this will help identify subcategories of depression. “Depression is such a heterogeneous disorder, it’s likely there are different subtypes with different mechanisms,” she says. “It might make it easier to identify treatments.” Geschwind’s team found no overlap between alcoholism and the other conditions they studied. This might be because the study didn’t include many people with alcoholism, says Austin. But it might hint that addictions work in a different way, says Kevin McGhee at Bournemouth University, UK. ■

forces will start using smart glasses more regularly soon. There are reasons to be cautious about equipping police with face-recognising smart glasses, says Paul Bernal at the University of East Anglia, UK. While the technology may make it easier for the police to apprehend suspects, it could also be used for more nefarious purposes, such as intimidating protesters. “When you feel safe and comfortable, you trust authorities with this stuff,” he says. “We’ll suddenly realise it’s disastrous if the political climate changes.” Chris Baraniuk ■ 17 February 2018 | NewScientist | 13

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Egg cells grown in lab may lead to better IVF

SpaceX proves Mars is in reach Leah Crane, Cape Canaveral

nearly 500 kilometres per hour, destroying two engines on the drone ship it was meant to land on. In the following hours, Starman and his car hurtled through the Van Allen belts – zones of intense radiation around Earth – and flew towards Mars. The car ended up on an orbit that will take it past Mars and near the asteroid belt, where it will travel as far as 254 million kilometres away from the sun. With this launch, Falcon

PEOPLE describe rocket engines as thunderous. Standing nearly 5 kilometres from SpaceX’s Falcon Heavy rocket as it took off for the first time, it felt more like I was inside a thundercloud. The success of the 6 February launch changed the game for commercial space flight. At 70 metres tall and with three boosters containing 27 engines, Falcon Heavy is the most powerful rocket on the market. It is capable “With such an ambitious mission so close, it is of putting 63,800 kilograms time to think about who into low Earth orbit or taking is in the driver’s seat” 16,800 kilograms to Mars. This first flight was a test, designed to show that the rocket Heavy has proved its ability to can carry a payload to space send payloads to Mars and beyond. without exploding. SpaceX CEO The atmosphere at Cape Elon Musk chose to send up his Canaveral was one of incredulous red Tesla Roadster, with a dummy elation as video of the Roadster named Starman at the wheel. flying away from Earth streamed The launch went off without to the press room televisions and a hitch, and the three boosters the public. While some bristled, disconnected from the rest of many reacted with glee and the rocket and flew back down to disbelief to the car hovering above Earth. The first two landed almost Earth. It was fun, it was silly and it simultaneously on their launch was beautiful. It was a symbol of pads. But the third did not touch the beginning of a new age of down so gently. It hit the sea going space exploration. 14 | NewScientist | 17 February 2018

Elon Musks’s car and a dummy astronaut leave Earth behind

But the car and its passenger made many wonder: was this launch about progress in space, or just a giant advert? The culture of private space flight is still under construction, and SpaceX is becoming a dominant builder. The firm has broken into a market historically dominated by governments. Customers can launch cargo on Falcon Heavy for just $90 million, far cheaper than other rockets that approach its size and even some smaller ones. Ultimately, Musk wants to put humans on Mars. This launch was a step toward his dream, but Falcon Heavy will not carry humans. Musk hopes that there will soon be a bigger, better option on the launch pad. People hoping to fly to the moon or Mars aboard a SpaceX rocket will have to wait for the planned BFR rocket. Musk said he hopes to test fly the BFR in the next three to four years. If the timeline gets pushed back, SpaceX will reconsider putting humans aboard Falcon Heavy. Either way, SpaceX is one step closer to being the first private firm to take humans to the moon and beyond. With such an ambitious mission close enough to touch, it is time to think about who is in the driver’s seat. ■

HUMAN eggs have been fully matured from their most primitive state in the lab for the first time. If these produce healthy embryos, the technique could lead to new fertility treatments. Evelyn Telfer at the University of Edinburgh, UK, and her team started with tiny pieces of ovarian tissue from 10 volunteers, taken during caesarean sections. The team looked for primordial follicles – small structures that each have the potential to release an egg. Most follicles remain inactive during a woman’s life, but some mature to release an egg in ovulation. They then placed 310 of these primordial follicles in a nutrient-rich liquid, where they started to grow. There is no particular ingredient that kick-starts growth, says Telfer. Instead, she believes that the act of dissecting the ovarian tissue to remove these follicles is enough to activate their growth. Once the follicles matured, Telfer’s team removed each of their eggs and grew them further. Only 32 grew big enough to resemble mature eggs, but these had all undergone a crucial cell division that makes them ready for fertilisation. The whole process took around three weeks (Molecular Human Reproduction, doi.org/ckdm). The team has now applied for a licence to fertilise these eggs with sperm. If this creates healthy embryos, the technique may improve IVF. For women undergoing surgery for conditions like endometriosis, removing some ovary tissue and promoting egg development in the lab may be preferable to the gruelling hormone treatments currently used to stimulate the release of multiple eggs. The technique may also lead to a safer way to restore fertility in women who have had cancer. Current approaches involve removing ovarian tissue then re-inserting it after treatment, but this carries a risk of reintroducing cancerous cells. IVF using lab-grown eggs should bypass this danger. Jessica Hamzelou ■

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DNA separation

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IN BRIEF Fish use hot seabed rocks as incubators

App guesses your emotions to target you with adverts IN THE mood for love? If so, you probably won’t want your phone to suggest a slasher movie or a thrash metal album. An app that works out how you are feeling could make recommendations that chime with your mood. Called MoodExplorer, the app was created by Wenzhong Li at Nanjing University, China, and his

Smartphones are ideal devices for such a system because they are filled with sensors that detect light, sound, motion and location, all of which might help deduce a user’s emotional state. In tests, MoodExplorer could guess the mood of users correctly from their smartphone data 76 per cent of the time, where mood was judged as either happy, sad, angry, surprised, afraid or disgusted. “There are much more important reasons to sense mood than to modulate which ads we get,” says Rosalind

colleagues. “Someone who likes romantic movies might prefer to watch an action film if they are feeling angry, perhaps, to relieve that anger,” says Li. “So a smart recommendation system really needs to take our moods into account.”

Picard at the Massachusetts Institute of Technology. “If a person’s mood data shows that they will get the most benefit from advice like: ‘take a walk with a friend’, ‘call your buddy, Joe’, ‘skip Facebook today’ or ‘go to bed 2 hours earlier tonight’, then that should be prioritised.”

Precision atomic clock goes for a ride AN ATOMIC clock has been used to take measurements outside a lab for the first time. These super-accurate clocks require extreme cold and stability. The tick of an atomic clock is measured by the frequency of radiation emitted when electrons around an atom change energy states. The best ones measure time with an error of only 1 in 1 billion billion: after ticking

for 32 billion years, they would be just 1 second off. Christian Lisdat at the National Metrology Institute of Germany and his colleagues set a strontium atomic clock on the move with a specially designed trailer (Nature Physics, doi.org/ckd3). It has rubber dampers to mitigate vibrations, and climate control to stabilise the temperature.

The team used the clock to test a prediction of Einstein’s general relativity: that time moves more slowly when gravity is stronger. According to Einstein, clocks run slower at sea level than at the top of a mountain, where the tug of Earth’s gravity is less strong. To confirm this, the team took measurements in the mountains of Modane, France, and in lowerlying Turin, Italy. Lisdat says they found that a year in the Alps is 84 nanoseconds longer than in Turin.

ONE species of deep-sea fish incubates its eggs in a seemingly impossible place: the baking hot rocks of hydrothermal vents. These seabed openings spew fluids from the planet’s bowels. “This is the first time this eggincubating behaviour, using heat from active hydrothermal vents, has been recorded in the marine environment,” says Pelayo Salinas de León of the Charles Darwin Foundation in the Galapagos, Ecuador. He says the heat may speed up development. Salinas de León and his colleagues used a remotely operated vehicle to explore the Iguanas-Pinguinos hydrothermal vents, north of Darwin Island in the Galapagos. They found 157 eggs, each about the size of a cellphone, which belonged to Pacific white skate (Scientific Reports, doi.org/ckcn). The eggs’ tough cases may protect them from corrosive vent chemicals.

Birds move muscles to ‘dream sing’ ZEBRA finches are such keen musicians, they appear to rehearse songs during sleep. We knew that while birds sleep, their brains make the activation patterns they show when they sing. Now it seems their vocal muscles move in response. A team including Gabriel Mindlin at the University of Buenos Aires in Argentina fitted electrodes to the vocal muscles of 10 sleeping zebra finches. They saw twitching, like during singing (PeerJ, doi.org/ckb9). In a second study, the team found they could trigger these movements simply by playing songs to sleeping birds (bioRxiv, doi.org/ckcp). The movements may help with learning, says Sharon Gobes at Wellesley College, Massachusetts. 17 February 2018 | NewScientist | 17

IN BRIEF

PARENTS of premature babies in intensive care units can provide basic nursing care. This isn’t to save hospitals money, but because it may help the babies grow faster: newborns who get parental care seem to put on about 8 per cent more weight over a three-week period. While most hospitals let parents stay with their babies in intensive care, they are often treated as visitors, says Karel O’Brien at Mount Sinai Hospital in Toronto, Canada. Her team has investigated offering training to parents, so they can take on some of the care of their premature babies while in hospital. This included feeding, giving oral medicines, taking temperature and completing charts. Parents had to be at the hospital for at least 6 hours per day, five days a week. Some care, such as giving injections, was reserved for medical staff. In the study of about 1800 babies born seven weeks or more early, after three weeks, babies whose parents underwent this training gained on average an extra 2 grams of weight a day when compared with similar babies at other hospitals (The Lancet, doi.org/ckcd). A confounding factor is that

JILL LEHMANN PHOTOGRAPHY/GETTY

parents more likely to opt for this might be more attentive in other ways, so the training and care may not be the cause of the weight gain.

18 | NewScientist | 17 February 2018

Weird hot ice of Neptune’s core gets forged on Earth NEPTUNE and Uranus have hearts of ice, but not like any ice you’ve ever seen. For the first time, a team has created the bizarre stuff that might occupy the cores of these ice giants. It is called superionic ice. It only occurs at temperatures matching those on the sun’s surface, and pressures exceeding a million Earth atmospheres – the environment predicted at the centre of ice giants. In this hot ice, the oxygen ions of the water molecules behave like a solid, staying in place to form a lattice,

while the hydrogen ions flow through it like a fluid. This structure gives superionic water ice resistance to very high temperatures. Marius Millot at the Lawrence Livermore National Laboratory in California and his colleagues have now made this ice in a lab. To do so, they started with ice VII, an exotic crystalline form forged only under intense pressure. They trained a laser on one of two diamonds holding a cube of ice VII, making a shock wave that travelled through the diamond and compressed the ice.

The melting temperature was 4726°C when under pressures equivalent to 2 million times that of Earth’s atmosphere (Nature Physics, doi.org/gcv8xr). This ice could explain the odd, swirling magnetic fields of Neptune and Uranus. Hydrogen ions in superionic water ice can carry electrical charge, making it good at conducting electricity and generating magnetic fields. The fields might be generated if a layer of ionic fluid water swirled around an inner core of superionic ice. SHINJI SUGIURA

Premature babies helped by parents

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A better drug for fighting asthma A DRUG that can relax specific muscles could become a new treatment for asthma. Many of the people who take current asthma drugs, called beta-2 agonists, become less sensitive to them. This is a dangerous prospect for the 300 million people worldwide with this airway-constricting condition. But Luis Ulloa of Rutgers New Jersey Medical School and his colleagues have been working on a new drug, called TSG12, that targets the smooth muscle cells that line our airways. The team says it relaxes tensed-up human muscle cells 100 times more effectively than some beta-2 agonists (Science Translational Medicine, doi.org/ckb8). When the team induced an asthma-like attack in mice using a dust mite allergen, they found that TSG12 reduced airway obstruction by 80 per cent. This may be about 30 times more effective than isoprenaline (isoproterenol), a beta-2 agonist. Because the TSG12 specifically targets the muscle cells involved in asthma, it may also have fewer side effects than beta-2 agonists. Trials of the drug in people should begin later this year.

Beetles escape from toad’s stomach BOMBARDIER beetles can spend almost 2 hours wallowing in the stomach juices of a toad, and still escape alive. The beetle squirts so much hot, toxic fluid into the toad’s stomach that the animal is sick, ejecting the beetle to freedom. Shinji Sugiura and Takuya Sato of Kobe University in Japan fed bombardier beetles (Pheropsophus jessoensis) to toads. Forty-three per cent of the beetles escaped, some after 107 minutes. Bombardier beetles famously produce jets of hot, corrosive and toxic chemicals from their rear ends

when threatened. To find out if this is how they escape, Sugiura and Sato fed single bombardier beetles to toads. They provoked half the beetles to jettison their toxic loads beforehand, depriving them of this means of defence. Only three of 37 disarmed beetles survived, whereas 16 out of 37 armed beetles escaped (Biology Letters, doi.org/ckcm). “The bombardier beetle ejects toxic chemicals inside the toad, forcing it to vomit,” says Sugiura. Bigger beetles survived best, probably because they ejected more toxic fluid and were harder to digest.

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ANALYSIS CAPE TOWN

A city without water Cape Town’s water reserves are so low that it may soon have to turn off the taps. How did it get this bad, asks Michael Le Page AS I fly south towards Cape Town, I pass over hundreds of kilometres of parched land, with not a speck of green in sight. Closer to the city, green fields start to appear and the city itself is full of lush parks and gardens. If it wasn’t for the massive posters at the airport, you wouldn’t know that this is a city about to run out of water. In fact, the situation is so bad that, on 1 February, residents were told to use no more than 50 litres a day per person. If the rains don’t refill the city’s reservoirs, the taps will be shut off in May: Day Zero. Cape Town’s problems are partly down to bad luck. Rainfall in the area, which the city relies on for its water, is highly variable and the past three years have been among the driest on record.

but manageable. They mean having the shortest of showers and not always flushing the toilet. Many thousands of people have installed boreholes so they can water their gardens or top up swimming pools. But most groundwater isn’t drinkable without treatment – there is a distinct sulphurous odour to the borehole water from one of the homes I visit. The situation will worsen dramatically on Day Zero, Cape Town’s water shortages mean regular trips to natural springs

Climate change might have made this more likely, but no one knows for sure (see “Is climate change to blame?”, right). The underlying cause, however, is simple: in several parts of South Africa, the supply of water hasn’t increased in line with growing demand. It has been clear since at least 2002 that, if nothing was done to increase supply, there would be massive water shortfalls. Cape Town was going to run out of water sooner or later; the drought has just made it sooner. While politicians may be happy to blame climate change, the dire situation is much more a result of institutional incompetence and alleged corruption. Until now, the tight water restrictions have been a nuisance, 20 | NewScientist | 17 February 2018

REUTERS/MIKE HUTCHINGS

“Millions of people will have to pick up their 25-litre-a-day rations from just 200 collection points”

when the city will start to turn off the taps to a million homes – currently estimated as 11 May. The idea is that places like hospitals and commercial districts will still get running water, but millions of people will have to pick up their 25-litre-a-day rations from just 200 collection points. Many are sceptical about whether this will work in practice. How will the traffic be managed? What about those who don’t have cars, or live in building without lifts? What about ill or older people, who can’t carry that much water? The answers aren’t clear.

Some people and businesses are planning to leave the city until the crisis is over. Most don’t have that luxury. As always, the poor will be hardest hit, with many farms already laying off workers and tens of thousands of jobs at risk if the situation continues. Now the city has to wait for the rainy season, which starts in April and peaks in June. No one knows what it will bring: the seasonal forecasts are no more reliable than tossing a coin. Even good rain might not bring immediate relief. Large parts of the reservoir beds have dried out,

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says water resources expert Anthony Turton, who lives in Cape Town. These “sponges” will soak up a lot of water before the reservoirs fill with usable water – how much is unknown. So, how did it come to this? “It’s a failure of the state,” says Turton. “It’s happening in various places across the country.”

Government failure The South African government’s own 2002 water strategy warned that several parts of the country faced large shortfalls in coming years. “Particular attention will therefore have to be given to ensuring adequate future water supplies to [the main metropolitan centres],” the strategy said. A 2007 report on the water supply to Cape Town and surrounding areas projected that, even in the best-case scenario,

demand would exceed supply IS CLIMATE CHANGE TO BLAME? no later than – wait for it – 2018. Global warming has probably made climate scientist Mark New at the One reason so little was done Cape Town’s water crisis a bit worse, University of Cape Town, as records is that under South Africa’s but it isn’t the main cause, as some for the region are limited. constitution, the national reports have suggested. It may be that global warming government, rather than Computer models predict that made the current drought more likely, provincial or city authorities, South Africa’s Western Cape will get but there is no clear evidence of this, is responsible for major water less rain as the planet warms, and he says. However, the warming is infrastructure. But South indeed there has been a slight decline increasing water losses from Africa’s Department of Water in rainfall over the past 50 years. evaporation, meaning less water and Sanitation has run up huge However, it is less clear how rainfall reaches taps even if rainfall remains debts due to mismanagement is changing in the mountains that constant. This is a factor in the current and alleged corruption and is in supply almost all of the water to Cape crisis, but by how much isn’t clear. New complete disarray, according to Town and farms in the area, says is working to answer that question. a November report by the South African Water Caucus, a network of organisations working on water issues recognised by the drinkable water from the sea and they ran into trouble. DWS. “This is an incredibly and groundwater could also Serious trouble,” says Muller. corrupt country,” Turton says. supply the rest of the city’s needs Only in May last year did city Instead of investing to boost during drought years. But during authorities finally accept that Cape Town’s water supply, the years of plenty, Turton stresses, they couldn’t just keep trying to department cancelled plans to water should be pumped back cut water use and hoping for rain. raise dams higher. underground, ready for when it The mayor unveiled plan B in Meanwhile, Cape Town’s is next needed. August: “to augment the system leaders decided to rely on limiting This is the approach adopted using a number of technologies demand rather than increasing by Perth in Australia over the past and sources by up to 500 Ml/day supply by, for instance, extracting decade. Faced with declining over the months ahead”. and treating groundwater. “They rainfall and emptying reservoirs, “We are doing absolutely had been advised to make some it has built major desalination and everything in our power to help investments,” says Mike Muller at water treatment plants, and is Team Cape Town to avoid Day the University of Witwatersrand pumping some of the treated Zero,” said Peter Flower, the city’s in Johannesburg, who oversaw water back into the local aquifer. director for water and sanitation the last major water project in Kirsty Carden, who studies in a statement. the Western Cape when he ran the water management at the In the first phase of the plan, national water department from University of Cape Town, agrees groundwater was supposed to 1997 to 2005. “They basically said, that the city shouldn’t keep provide 100 Ml/day, with another ‘we are so good at managing our 100 Ml coming from temporary “A 2007 report projected water we don’t have to’.” desalination plants. Yet six that even in the best-case South Africa needs to change months on, plans have hardly scenario water would run its entire approach to water advanced and almost no extra management, says Turton. Rather out no later than 2018” water has been produced. than hoping to store enough river In theory, it should be possible water behind dams to cope with relying on dams alone. “We have to ramp up desalination very droughts, it needs to turn to to build in some resilience.” quickly, for instance by bringing recycling, desalination and But recycling and desalination in ships equipped to do the job. groundwater storage, he says. aren’t cheap, she points out, and But so far construction has Turton estimates that recycling Cape Town has had many other started on just four small plants, Cape Town’s waste water could urgent problems to address, which will produce only tens of supply as much as 400 million such as housing the million millions of litres a day. It will take litres (Ml) a day – more than people living in poverty. “These years to ramp up groundwater half of the city’s current needs. people are already collecting extraction, says Turton, not least At present, the city only reuses a water in buckets as a daily part because of the time it takes to get tiny fraction of its water and only of their life,” says Carden. planning permission. as “grey” water for plants, rather Delaying investment in Cape Town is almost out of time. than treating it to drinking other water sources, however, Its fate is now largely down to the standard. “Water is an infinitely could prove to be a very costly vagaries of the weather. If the rains renewable resource,” says Turton. mistake for the city. “They didn’t don’t come, the taps go off and the Desalination plants that create do what they should have done city enters uncharted territory. ■ 17 February 2018 | NewScientist | 21

COMMENT

Ready for the next leg? Will we realise the exponential power of quantum computing within five years as many now predict, wonders Graeme Malcolm THOSE racing to realise the potential of quantum computing have been busy signalling that within the next half decade a functional machine will be here – one capable of undertaking tasks unimaginable in the context of today’s classical supercomputers. As we saw with the rise of standard digital computers, timelines are volatile and uncertain, with developments often taking longer than predicted. But there are good reasons to think that we could be on the cusp of the greatest computing revolution to date, even if it is not done and dusted in exactly five years. One hopeful sign is that scientists and companies are making big investments. These are coming from the likes of IBM, Google, Intel and Microsoft and show they think this technology can provide a step change key to

their growth. And progress so far means the paths to quantum computers have now emerged. The real question is not if they will arrive, but what form they will take and what they might be used for in the near term. Why is quantum computing worth pursuing? The reason is the quantum bit or qubit. Unlike a digital binary bit, which can only be on or off, a qubit can be “on” or “off”, both “on” and “off”, and neither “on” nor “off”. When entangled with other qubits, quantum technology allows for exponentially more processing power than binary systems. It will deliver a quantum advantage, or so-called quantum supremacy, that will take computing far beyond the powers of current classical computers. To achieve this, a system would need to function with between 50 and 100 qubits.

Spell it out Label all meat as stunned or unstunned at slaughter, says Danny Chambers “BAN halal and kosher meat in the UK.” This is the demand of an online petition signed by about 90,000 people so far. It is far from the first. This example is full of phrases such as: “The people of Britain wish to remain a civilized society not a barbaric one. We denounce halal & kosher meat in our country.” 22 | NewScientist | 17 February 2018

they stand, the calls for change are often enthusiastically shared online by far-right groups, making sensible debate difficult. Why is this an issue at all? In the UK, animals have to be stunned before slaughter, unless being killed according to religious rules. Stunned animals are unconscious when their throats are cut. This means they are not aware of the severing of major blood vessels. Animals not stunned are fully conscious and die when enough

Such calls are becoming perennial, but the continual focus on religion is getting in the way. It simply heightens emotions and diverts attention from the key concern – animal welfare. It is the distinction between stunned and “Sheep are conscious for up to 20 seconds once their non-stunned slaughter, not throats are cut and cattle religious vs non-religious, that for up to 2 minutes” should be front and centre. As

blood is lost. This is stressful, induces panic, and the animal will inhale blood and experience pain. Sheep retain consciousness for up to 20 seconds once their throats are cut, cattle for up to 2 minutes, and poultry can take even longer. Some Muslims believe meat cannot be halal if pre-stunning is used. However, many Muslims think pre-stunning is compatible with halal slaughter; as a result about 80 per cent of UK halal meat is pre-stunned. This is not so with Jewish shechita slaughter – all kosher meat is unstunned. What is the answer? From a welfare point of view, a ban of non-stunned slaughter would be

For more opinion articles, visit newscientist.com/opinion

Graeme Malcolm is CEO and co-founder of M Squared, a UK firm developing photonics and quantum technology

ideal. Failing that, a requirement to label meat as stunned or non-stunned would allow consumers to choose better welfare if they so wished. What’s more, many people don’t know that the hindquarters of animals from shechita slaughter are often not seen as kosher, so are sold, unlabelled, in the general food chain. Labelling this way would identify it. To make progress on these issues, we must put the focus on welfare rather than religion. ■ Danny Chambers works as a vet in Bristol and sits on the British Veterinary Association’s policy committee

INSIGHT E-cigarettes

MATT CARDY/GETTY

Superconductors, ultra-cold atoms and ultra-cold ions are among the means to create or simulate qubits. Each faces challenges. Ultra-cold atoms promise greater scale, but have yet to produce the required qubit accuracy (too many errors in quantum computation destroys the quantum advantage over standard computers). Ultra-cold ions provide reduced errors and scalability is beginning to be realised, but so far this is limited to 10 to 20 qubits. And the use of superconductors relies on advances in materials science. Which will prove best is unclear. What is clear is that as we generate ever more data, current computers are hitting processing limits. This is where we will see the greatest advantages of quantum versions. From modelling climate change and weather systems to population dynamics, quantum-powered capabilities will solve problems classical computers can’t. Five years to the revolution? There are growing grounds for optimism for specialised uses. Just don’t expect a quantum PC on your desk in 2023. ■

Switching to vaping will save lives Clare Wilson

vaping are unknown and it should be discouraged. In countries such as Australia, it is even criminalised. Public Health England, on the other hand, has long been in favour of vaping, and last week called on companies and even hospitals to introduce vaping rooms, like old-style smoking rooms. But there is another change that needs to happen if we want more people to switch. Vaping is not as easy to take up as smoking. There are several kinds of products available. The most basic version, sometimes

IT IS an unprecedented turnaround. E-cigarettes, once painted as a new and sinister health risk, are now being promoted as a public health lifeline – in the UK, at least. Yet if we want to make the most of their potential, healthcare staff need to put aside their preconceptions and embrace them more enthusiastically. The rationale for vaping is clear. Regular tobacco smoking is one of the biggest lifestyle contributors to death and disease worldwide, causing heart disease, strokes and “Not everyone is keen to a long list of cancers. While the get health advice from flavourings in e-cigarettes could in vaping shops, which theory harm the lungs, vaping has often look like bars” been calculated to carry at most 5 per cent of the risk of smoking. It is hard to quit smoking – about called cigalikes, don’t give a quick90 per cent of attempts end in failure – enough nicotine hit to satisfy most but vaping makes it easier. By one smokers and people who start with estimate, the failure rate drops to these often relapse, says Caitlin Notley 60 per cent when people become at the University of East Anglia, UK. vapers instead. More complex e-cigarettes require For once, the UK has one of the most purchasing several items of kit, such enlightened and progressive stances as the device, nicotine liquid and to a social ill. In many countries, the charger, and some people need advice official stance is that the risks of to start off. New users may also

benefit from information on dosing and even how to inhale. At the moment, those giving such help are generally the staff of the specialist vape shops springing up everywhere. A few doctors work with these outlets, visiting to provide health education materials and actively encouraging their patients to visit, Notley’s team found in a study published last week. This is not common practice, though, partly because of e-cigarettes’ shady reputation. And not everyone is keen to get health advice from vaping shops, which often look like bars or smartphone stores. In theory, pharmacies would be ideally placed to step in but again, anti-vaping sentiment has made them reluctant. The UK’s Royal Pharmaceutical Society, the body that represents pharmacists, told its members not to stock e-cigarettes at all in 2014, although many shops flout this, and that stance is now under review. Notley has called for more health professionals to work collaboratively with vaping shop staff, who are often former smokers themselves and can be highly knowledgeable about their wares. “Most pharmacists could certainly learn from vape shops,” she says. It’s not the most conventional way to combat a public health problem. But when you see a lifeline it makes sense to grab it with both hands. Q 17 February 2018 | NewScientist | 23

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Tackling HIV Just 30 years ago, an HIV diagnosis was a death sentence. Today, thanks to a scientific partnership of epic proportions, it can be manageable with a single daily pill

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N 1981, doctors in the US became aware of a strange phenomenon. An unusual number of healthy young men in Los Angeles and other cities were falling ill and dying from rare infections and cancers. Their symptoms suggested that something was weakening their immune systems, leaving them vulnerable to diseases they would normally fend off. More mysterious still, the condition appeared to be most prevalent among the gay community, intravenous drugs users and people who had frequent blood transfusions. Similar cases emerged in other countries and it soon became clear that the world was facing an epidemic of a new disease for which there was no cure. Doctors called the illness Acquired Immune Deficiency Syndrome (AIDS) and within three years had found it was caused by a retrovirus. This virus could be passed on in several different ways: through unprotected sex, blood transfusions, sharing needles, and through pregnancy, childbirth or breastfeeding. But how it could be stopped wasn’t clear. This was the start of an epic journey to find a treatment for one of the biggest killers of the last half-century. For years, the virus that causes AIDS, the human immunodeficiency virus or HIV, had the upper hand. By 2000, 33 million people were infected, 14 million had died, and in Africa it had become the number one cause of death through infectious disease. Today, thanks to a series of biomedical breakthroughs and the painstaking work of thousands of researchers around the world, the tables have turned. Those with HIV can now live longer, fuller lives by taking a single daily dose of antiretroviral medicine. “Today, HIV is a chronic illness,” says Professor Chloe Orkin, a consultant physician at the Royal London Hospital and Chair of the British HIV Association. Indeed, the outcomes are better than for many chronic illnesses. “Those diagnosed early are likely to have a normal life expectancy, which isn’t always the case with long-term illnesses like diabetes,” she says.

In September, the US Centers for Disease Control and Prevention declared that people with minimal amounts of the virus in their blood have “effectively no risk” of passing it to their partner through unprotected sex. That’s one reason why the future for someone diagnosed with HIV in 2018 is a great deal brighter than it was 30 years ago. At that time, researchers had little idea what made HIV so difficult to beat. We now

“The quest for new HIV treatments has produced some remarkable progress” know the virus attacks a person’s T lymphocytes, a type of white blood cell that plays a central role in the immune system. Once inside a T-cell, the virus starts to reproduce. First, it transcribes its singlestranded RNA sequence (its genetic blueprint) into a double-stranded DNA sequence using an enzyme called reverse transcriptase. The viral DNA then fuses with the T-cell’s own DNA, allowing it to replicate

and create HIV proteins whenever the T-cell is activated. New HIV particles are released into the bloodstream, where they target other T-cells, and the process starts all over again. The first success in the search for HIV treatments was a class of antiretroviral drugs called reverse transcriptase inhibitors (see diagram below). These disrupted the early stages of the virus’s life cycle by preventing the reverse transcriptase enzyme from synthesising DNA from viral RNA. That made it impossible for the HIV to reproduce. Some of the first reverse transcriptase inhibitors emerged from collaboration in the early 90s between the Institute of Organic Chemistry and Biochemistry in Prague, the Rega Institute for Medical Research in Leuven, Belgium, and Gilead Sciences. The three-way partnership led to the development of several antiretroviral approaches that are still relevant in HIV treatment today. By the mid-90s, AIDS had become the leading cause of death among young adults in the US. At this time, medical authorities licensed a second class of antiretroviral drugs

Halting HIV reproduction The HIV retrovirus enters the host cell and releases viral components

Integrase Reverse transcription

HIV DNA

Deoxynucleotides HIV RNA

HIV RNA

Reverse transcriptase

The process of reverse transcription uses HIV RNA to generate HIV DNA by assembling the cells own deoxynucleotides

HIV DNA chain produced by reverse transcription

G-STOCKSTUDIO/GETTY IMAGES

The future is increasingly brighter for people with HIV

The integrase inserts the HIV DNA into the host cell's DNA and produces new copies of the HIV RNA

The HIV RNA and other viral components leave the cell forming a new retrovirus

Host DNA

Cell nucleus

HIV RNA

Reverse transcriptase inhibitors stop this process, in this case by taking the place of deoxynucleotides, attaching to the HIV DNA chain and terminating it

called protease inhibitors. These target another of the virus’s enzymes responsible for cleaving the long chains of viral DNA into individual proteins. With protease disabled, the virus cannot reproduce. Later, researchers chalked up another small victory with a set of drugs that attack the middle part of the virus’s reproductive cycle. Integrase inhibitors disrupt a viral enzyme that integrates the HIV DNA with that of the T-cell. Each of these was an important step, yet it was clear early on that no single treatment used in isolation can keep HIV at bay for long. This is because the virus has a remarkable ability to mutate as it replicates and this allows it to become resistant to a drug quickly. “HIV actually makes a lot of mistakes when it replicates, generating a lot of mutations,” explains Peter Borg, Medical Director at Gilead Sciences. “If you don’t significantly inhibit the replication, you can end up getting a lot of resistant virus.”

The big breakthrough came in 1996, when researchers realised that the best way to suppress HIV replication was to use a combination of drugs – an approach known as highly active antiretroviral therapy (HAART). The only way the virus could become resistant to this approach would be to develop several mutations at the same time, which is highly unlikely to happen. The most recent HAART treatments contain two reverse transcriptase inhibitors and a third drug from another class, usually a protease inhibitor or an integrase inhibitor. Together these can reduce the amount of virus in the blood to undetectable levels and allow the immune system to recover, provided they keep taking the treatment. When HAART was introduced, people had to take handfuls of drugs several times a day, and the side effects were often terrible. Today the drugs are far easier to take and can be combined into one or two daily pills. That approach has had a huge impact. Combination therapy has turned what used to be a death sentence into a chronic illness. However, the HIV epidemic is far from over. One of the biggest problems, says Borg, is that between a quarter and half of people with HIV are diagnosed when their immune systems are already depleted and so are at risk of other potentially fatal diseases and overall poorer prognosis. “A major challenge is to get people diagnosed and linked to care and on to treatment in a timely fashion.” In the meantime, there is an urgent need to make the latest therapies and diagnostic tools more available in certain developing countries. In some areas, people with HIV are still treated with old-generation medications associated with more side effects. And the stigma around the disease is dissuading people who may be infected from coming forward for early testing. Finally, there is the issue of ensuring the long-term health of people living with HIV as life expectancy continues to increase. The quest for new HIV treatments has produced some remarkable progress and these are now beginning to spread. The next article in this series will explore how modern HIV treatments are becoming more widely available across the planet.

For more see: @GileadSciences Date of preparation: January 2018 Job code: 999/IHQ/18-01//1004

APERTURE

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Forever blowing bubbles A HUMPBACK whale surfaces, its mouth distended with krill and thousands of litres of water. It is the final stage of bubble-net hunting, a sophisticated technique employed by these huge mammals. A whale and its partner, visible just below the water’s surface, have together created a trap for the krill – their main food source – by swimming around exhaling columns of bubbles through their blowholes. The spiral of columns surrounds the crustaceans, creating a barrier they are unwilling to swim through. They move close together, and that’s when the whales dive, turn and swim upwards into the krill, mouths gaping. It is an effective strategy, but not well understood. A drone took this photo as part of a project led by David Johnston of Duke University in Durham, North Carolina, to learn more about the whales’ behaviour. A laser altimeter fitted to the drone allows his team to calculate its altitude and thus the sizes of the whales and their bubble nets. The picture was taken about 200 kilometres off the western Antarctic Peninsula. The whales feed here all summer, building up supplies of fat. They need to, because they then migrate to their breeding grounds in the Gulf of Panama and will not eat again until they return to the Antarctic, six months later. Julia Brown

Photograph Duke Marine Robotics and Remote Sensing Lab NOAA Permit 14809-03, ACA Permit 2017-034

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CHRISTOPH HETZMANNSEDER/KEYSTONE-FRANCE/REB IMAGES/GETTY

COVER STORY

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Blast from the future To make sense of quantum weirdness, we need to rethink cause and efect, says Adam Becker

I

F YOU were to break your arm tomorrow time warp, we need to rewind to the 1930s, afternoon, would you suddenly find it when the outlandish physics of quantum hanging useless in a sling this morning? mechanics was threatening to overturn Of course not – the question makes no sense. centuries of conventional wisdom. The theory Cause always precedes effect. But maybe life seemed to imply that subatomic particles isn’t quite so straightforward for a photon. exist in a vague cloud of probabilities until In the subatomic realm, where the laws of they are measured, at which point they snap quantum physics make seemingly impossible into a definite state. But Einstein, for one, feats routine, the one thing that we always wasn’t having it. “God doesn’t play dice with considered beyond the pale might just be true. the universe,” he insisted. This idea that the future can influence the Yet despite his distaste for randomness, present, and that the present can influence the it was a different feature of the quantum past, is known as retrocausality. It has been world that Einstein found truly unbelievable. around for a while without ever catching on – and for good reason, because we never see “The idea that the present effects happen before their causes in everyday life. But now, a fresh twist on a deep tension in influences the past seems the foundations of quantum theory suggests absurd at first glance” that we may have no choice but to think again. No one is saying time travel is anything In a thought experiment, he pointed out that other than fantasy. But if the theorists going if the probabilistic description of the quantum back to the future with retrocausality can world were the true state of things, then make it stick, the implications would be measuring one subatomic particle could almost as mind-boggling. They could not instantly influence the state of another, only explain the randomness seemingly regardless of the distance between them – inherent to the quantum world, but even a strange phenomenon that became known remake it in a way that finally brings it into as entanglement. line with Einstein’s ideas of space and time – Imagine that two particles collide and fly an achievement that has eluded physicists off in opposite directions. Under quantum for decades. “If you allow retrocausality, it is rules, these particles are now entangled. possible to have a theory of reality that’s more Their velocities are unknown. But if you compatible with lots of things that we think measure the velocity of one of them, you’ll should be true,” says Matthew Leifer at immediately get the velocity of the other, Chapman University in Orange, California. even though there was no way to know this To get to grips with this particular brand of in advance. So you have a choice: either the

particles can instantaneously affect each other when measured, or they had definite velocities all along, even though quantum physics was incapable of determining them. Einstein’s money was on the second option. Instantaneous connections between distant particles were impossible according to his theory of special relativity, which enforced a strict speed limit for how fast signals can pass between objects – the speed of light. In fact, he was adamant that all theories must uphold this ban on instantaneous signals, a principle known as locality. Hence he damned entanglement as “spooky action at a distance”, suggesting it would turn out to be a mirage once a more fundamental theory came to light. But entanglement never did vanish. Instead, it made its presence felt in the laboratory. In the 1960s, Northern Irish physicist John Bell came up with a brilliant way to put spooky action to the test, and it has since passed with flying colours every time. The examination culminated in 2015 with a “loophole-free” Bell test hailed as the nail in the coffin for locality. Like it or not, spooky action at a distance – or non-locality – is a thing. Or is it? Retrocausality could save us from non-locality. The trouble is that it seems absurd at first glance. It jars with everyday experience, in which time flows forward and effect follows cause. But backward causation is no harder to swallow than entanglement – and it might just solve two of the greatest conundrums in physics. > 17 February 2018 | NewScientist | 29

DENISE TAYLOR/GETTY

“Certainly, John Bell himself thought his work revealed a deep tension with special relativity,” says Huw Price, a philosopher of physics at the University of Cambridge. “The appeal of retrocausality is that it removes that tension.” By restoring a kind of locality, retrocausality gives us the chance to rebuild quantum mechanics in a way that works with Einstein’s theory of general relativity, which shows how gravity results from the warping of space-time by matter and energy. “Most people have tried to recast gravity in quantum terms, but maybe it is the other way around,” says Ken Wharton, a theorist at San Jose State University in California. “Maybe what we need to do is recast quantum theory in space and time. Retrocausality looks like one way to do that.” The notion that the present might influence

interpretations springing up to explain the perplexing results of the Bell experiments, retrocausality never really caught on. It wasn’t until 2010 that Price attempted to resuscitate the idea. His case revolved around a principle called time-reversal symmetry. This states that, mathematically speaking, the fundamental laws of physics work the same going backwards in time as they do going forwards. Of course, that doesn’t tally with our everyday experience: you can’t unscramble an egg, say, or unshatter a glass. (Physicists suspect that has something to do with the second law of thermodynamics, which says that entropy – the amount of disorder – always increases over time when large numbers of particles are involved.) But the fact is that fundamental physics is almost entirely indifferent to the direction of time.

But retrocausality is becoming harder to avoid. In 2017, Leifer and Matthew Pusey, now at the University of Oxford, found a way to close the loophole in Price’s argument. By merging Price’s ideas with Bell’s, Leifer and Pusey managed to show that retrocausality is necessary to save time-reversal symmetry regardless of whether the quantum state is real. This leaves another tricky choice: abandon time-reversal symmetry or embrace the idea that in the fuzzy quantum realm, the future really can influence the past. Leifer is among those attempting to make good on the second option. The key might be a feature of relativity called the block universe. In its marriage of space and time, Einstein’s great theory fatally undermines the concept of “now”. What is happening “now” in a particular location depends on where you are

the past in the quantum realm can be traced back to Paris in the late 1940s, when a young physicist called Olivier Costa de Beauregard spotted a way to explain pairs of entangled particles without invoking non-locality. Perhaps, he suggested, measuring one particle sent a signal back in time to the point in the past when the pair collided. The signal could then turn around and travel forwards in time with the other particle, ensuring its velocity was exactly in accordance with the measurement of the first one. If a signal took this path, you could preserve locality without requiring the two entangled particles to have determined their velocities at the point of their collision. No instant communication, no violations of relativity. At that point, no one had shown that non-locality was real. Only when Bell came along was there any reason to take de Beauregard’s proposal seriously. But even then, with all manner of clever

Nearly all physicists agree that most of the basic laws of physics obey time-reversal and they would be loath to give it up. With that in mind, Price pointed out that if the laws of quantum physics obey time-reversal symmetry, as they seem to, then retrocausality is inevitable. Yet there was a loophole in his argument. Price had

and how fast you’re moving, so two different observers may see different things at the same time in the exact same spot. This makes “now” an illusion. Time doesn’t really pass at all, and our perception that it does is due to our limited perspective on the world. In reality, past, present and future form a single, ever-existing block. In a block universe, quantum retrocausality wouldn’t look so strange. If the past and the future coexist – if past events don’t fade away before future ones come into being – the future could easily influence the past. What we need now, says Leifer, is a new version of quantum theory that incorporates the block universe to allow for retrocausality to emerge naturally. “The idea here is that you would formulate a theory of quantum physics over all of space-time, all at once,” he says, urging us to think of quantum cause and effect like a jigsaw puzzle. “When you do a jigsaw, you don’t do the bottom row first, and

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“Now is an illusion: past, present and future form a single, ever-existing block” assumed that the quantum description of a particle, known as the quantum state, corresponded to a real thing in the world, as opposed to being a mathematical tool for handling our own ignorance of said particle. For many, this was reason enough to ignore Price because the true status of the quantum state remains debatable.

then the next. Each piece imposes constraints on the ones around it. So physics could be like that: each region of space-time could impose constraints on the neighbouring regions.” But if the quantum world is a block universe shot through with retrocausality, why don’t we see retrocausality in our everyday lives? After all, we are all made of quantum stuff. The answer boils down to quantum uncertainty. Heisenberg’s uncertainty principle states that it is impossible to know both the position and momentum of a particle at the same time. So there are features of the quantum world that are persistently hidden from us, and this is ultimately what allows for retrocausation without letting us send signals to the past. “If my choice a minute from now determines one of these things that I don’t know, then I can’t send a signal back to myself,” says

Wharton. “And yet it’s still retrocausal.” Wharton is among those who argue that when you really think about it, retrocausality is no crazier than entanglement. And besides, he says, it brings plenty of advantages – not least the opportunity it affords physicists to remake quantum theory in a way that works with space-time. By restoring a form of locality, retrocausality might even lead to the long-sought explanation of how gravity manifests at the quantum scale.

God plays sudoku “A lot of avenues have been left unexplored because people have been taught to think in this Newtonian picture of states evolving forwards,” says theorist Emily Adlam at the University of Cambridge. “Retrocausality is going to open up many new possibilities that might hopefully get us out of the rut we’re in.” It might also help to explain where the

randomness in quantum physics that never sat right with Einstein comes from. According to Adlam, retrocausality suggests a neat solution: quantum randomness is an illusion that appears because we’re only seeing part of the picture at any one time.

“Retrocausality might even explain where quantum randomness comes from” In that case, Einstein was right. “God doesn’t play dice, he plays sudoku,” says Adlam. If you were doing a sudoku and you started on the left and moved towards the right, it would look as if you were seeing random events, she says. “But if you look at the whole thing at once… you can see all the rules, you can see

that there’s actually a unique deterministic solution from these global constraints to the whole grid.” Similarly, in a retrocausal version of quantum physics, what happens here and now could have effects on the distant past of a far-flung galaxy, effects that only make sense in the context of the “all-at-once” picture of the block universe. This may seem like a drastic departure from the ordinary laws of physics as we think of them, but to Adlam, that’s not a problem. “It’s quite naive of us to suppose that the laws of nature would take the form that is most convenient for us,” she says. “To me, it’s not in fact extreme or weird at all to go to this retrocausal picture.” Not everyone shares Adlam’s enthusiasm. While it is true that time-reversal symmetry is a cherished property of nearly all the fundamental laws of physics, the version Leifer and Pusey use isn’t the usual one. Rather than time-reversing the laws of physics

themselves, they time-reversed the setup of their thought experiment, and showed that the results remained the same. This distinction gives sceptical physicists pause. What’s more, retrocausality doesn’t answer every question facing quantum physics – at least not yet. “The next chapter in this story is just starting,” says Wharton. The hard work begins now, he adds, as researchers attempt to develop a complete retrocausal theory, one that reproduces all the usual results of the hugely successful standard quantum theory. But if recent work by Sally Shrapnel and Fabio Costa at the University of Queensland in Australia is anything to go by, even a fully retrocausal quantum theory wouldn’t solve all the problems that niggle away at other interpretations of quantum physics. Although retrocausality handily accounts for the results

of the Bell experiments, there is another issue, known as quantum contextuality, which may yet stop it in its tracks. Contextuality says that the outcomes of quantum experiments depend on what other experiments are conducted at the same time – a strange idea that physicists would prefer to be rid of. Now, Shrapnel and Costa have shown that retrocausality cannot easily dismiss it. Although Shrapnel agrees with Leifer that retrocausality is worth investigating, she sounds a word of warning. “The retrocausal interpretation is not the free lunch that perhaps you might think it is,” she says. “It’s not going to be as simple as postulating backwards-in-time causal influences. We’re going to need something even more exotic than that, and I think that’s kind of cool.” Q Adam Becker is a writer based in Oakland, California, and author of What is Real? The unfinished quest for the meaning of quantum physics 17 February 2018 | NewScientist | 31

Silence o f the plants The strange and fragrant language of plants is being destroyed by human activities, fnds Marta Zaraska

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N THE classic post-apocalyptic novel The Day of the Triffids, giant carnivorous plants terrorise humanity. Triffids can walk and are equipped with venomous stingers, but their real power lies in their ability to communicate and so plot against us. It sounds far-fetched, but since John Wyndham’s book was published in 1951, one aspect of this fiction has proved to be science fact: plants do talk to one another. If you stroll through a forest and take a deep breath, you can smell the “words” – complex volatile chemicals such as beta-pinene, which smells fresh and piney. Plants produce thousands of these, combining them to create “sentences”. However, this fragrant language is under threat. Air pollution is disrupting floral scents, turning their messages into gibberish. Not only is this having an impact on plants’ abilities to survive, it is also bad news for pollinating insects – and for us, because it affects everything from crop yields to the smell of our favourite flowers. Luckily, there is a way we can help our botanical friends fight back. It has long been known that insects such as pollinators and pests can distinguish between plants by the unique bouquet of chemicals they release. What’s new is the idea that plants use their emissions to talk among themselves. “Plants release volatile chemicals into the atmosphere – these can be viewed as a language in the sense that a plant releasing the

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chemicals can be viewed as ‘speaking’ and the plant receiving them as ‘listening’ and then responding,” says chemical ecologist James Blande at the University of Eastern Finland. Many plants warn one another of an impending pest attack. When a tomato plant is infested with cutworms, for example, it releases a cocktail of volatile chemicals into the air that is picked up by others nearby. On “hearing” the warning, these tomato plants respond by producing glycoside, which triggers the release of a poison to ward off the hungry caterpillars. Other plants use a similar approach to summon help from friendly insects. When aphids infest soybeans, for instance, the plants sound a chemical “burglar alarm” that brings ladybirds to the rescue. Now we are discovering that air pollution can disrupt these communications. In one study, Blande and his colleagues put individual bumblebees into a chamber containing paper flowers resembling those of black mustard. When the scientists injected the scent of real black mustard flowers that grew in either a clean or polluted atmosphere the bumblebees’ reactions were unequivocal: they were immediately attracted to the unpolluted scent, while that from polluted air left them buzzing around aimlessly. What’s going on? In the past few years, ozone and nitrogen oxides have emerged as the main gibberish-inducing culprits. These ultimately result from vehicle and power plant

emissions, with diesel exhaust a particular problem. Both ozone and nitrogen oxides react with the volatile chemicals released by plants. This changes the smell of their bouquet by degrading some compounds in the mix more readily than others. When monoterpene limonene, a common “word” of oranges, is mixed with ozone, for example, it degrades into as many as 1200 different compounds. Such degradation can happen surprisingly fast. Ecologist Robbie Girling at the University of Reading, UK, and his colleagues exposed eight common compounds produced by flowers to diesel exhaust. “What we weren’t expecting was the speed with which these reactions seem to be occurring,” he says. “Within a minute, which is the shortest time period our method could resolve, we couldn’t see anything of one of the compounds. It was instantaneously undetectable.” (See “When plants talk dirty”, page 34) It’s not just the clarity of plant language that gets disrupted, the “loudness” is affected, too. The scent of plants simply can’t travel as far in polluted air as in pristine conditions. To

GONÇALO VIANA

“Scents that could once be picked up kilometres away now travel only metres” find out how much things have changed since pre-industrial times, Jose Fuentes at the University of Virginia and his colleagues made a computer model that included historic air pollution levels. It revealed that scents produced by flowers that could once be picked up kilometres away now travel as little as 200 metres. Even between clean and dirty environments today, a similar reduction in signal can be seen. Take lima beans. When one plant is attacked by spider mites, it emits chemical signals that prompt others nearby to produce more sugary nectar. This, in turn, attracts predatory mites, which eat the attackers. If the atmosphere is clean, Blande found, the beans easily communicate with neighbours growing 70 centimetres away. But if ozone concentrations top 80 parts per billion (ppb), their warning cries can’t be heard more than 20 centimetres away. This 80 ppb of ozone pollution seems to often be the level above which problems start. That’s bad news because in urban areas concentrations of ozone often exceed 100 ppb, and sometimes even 200 ppb. It is less clear when nitrogen oxide levels become a > 17 February 2018 | NewScientist | 33

When plants talk dirty Plants produce volatile compounds to communicate. In different combinations, these can tell other plants to “prepare for attack”, or they can attract or repel insects. However, air pollution is disrupting these lines of communication by breaking down many of these chemicals (see main story), including some of the most common ones that give plants their distinctive aromas.

Myrcene A peppery, woody scent with a touch of carrot, myrcene is produced by many plants including rose and orchid flowers, and tobacco and tomato leaves. It degrades readily in the presence of diesel exhaust, which can confuse pollinators such as bees.

Monoterpene limonene A citrusy scent produced by oranges, lemons and cannabis, this degrades into as many as 1200 different compounds when mixed with ozone.

Beta-caryophyllene A clove-like scent produced by roses and lavender, this is readily destroyed by pollution, which may explain why flowers in urban gardens are lacking in aroma.

Beta-ocimene With its tropical citrusy odour, this is more quickly broken down by pollution than any other scent tested. Mixed with diesel exhaust it becomes undetectable in less than a minute.

Benzaldehyde This almondy scent reacts with ozone slowly compared with other volatile compounds produced by plants.

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problem, but in the UK, nitrogen dioxide from diesel exhaust is undoubtedly doing damage. Its impacts on human health mean there are legal limits for emissions, but these are regularly breached. For example, hourly levels of nitrogen dioxide shouldn’t exceed 200 micrograms per cubic metre more than 18 times in one year, yet in parts of London this happened in just the first few days of 2017. Urban gardeners may notice the effects. “These pollutants definitely affect the smells from plants,” says Blande. Nitrogen oxides can reduce the time for which some floral scents linger in the air from 18 hours to a mere 5 minutes. Scented flowers such as roses don’t have the same strong aroma in cities that they have in rural locations, says Blande. You have to get really close to smell them, and even then you are unlikely to experience the full aroma because compounds such as the clove-like beta-caryophyllene are quickly destroyed by pollutants. It’s not just our noses and poetic natures that suffer when the scent of flowers is disrupted. “I don’t think it would be too big a jump to suggest that air pollution could also be a factor in reducing the numbers of flying insects,” says Girling. Insect numbers have been falling globally, a situation that came to prominence in 2017 when it was revealed that insects in German nature reserves had declined by an alarming 75 per cent in just 27 years. Miscommunication between flowers and insects could be particularly significant for pollinators such as bees. Although no one has yet measured the overall impact this has had on bee numbers, Girling has found that the common volatile myrcene is particularly

easily damaged by diesel exhaust – and this can lead honeybees astray. His team found if they removed myrcene from flowery scents, only 37 per cent of bees still recognised them. As the language of plants becomes increasingly garbled, the impact on the survival of pollinators and plants themselves threatens to destabilise whole ecosystems, with serious implications for the natural world and commercial crops. Efforts are under way to reduce pollutants such as diesel exhaust but progress is slow. The good news is that there is a simple and immediate step we can take to help plants communicate: grow more of them to mop up the pollutants. Some plants are better at this than others, but research suggests reforestation is a particularly good option because trees have a large surface area to absorb ozone and nitrogen dioxide from the atmosphere. Urban planners are already moving in the right direction. Many cities now have vertical gardens and living walls. Near London’s Victoria train station, for example, a 20-metrehigh wall contains more than 10,000 plants. Even trees are being planted on the sides of buildings. In 2014, the first forest skyscraper went up in Milan, boasting 800 trees and almost 20,000 other plants. In China, the Nanjing Green Towers, currently under construction, will have 1100 trees along with thousands of other plants, and a whole forest city is planned in Liuzhou. Such urban forests do, of course, have their communications undermined by pollution, but they also serve to reduce its impact on other plants. What’s more, with more plants closer together they don’t have to shout as loudly to be heard. It seems like a no-brainer. Nevertheless, Fuentes injects a note of caution. He points out that some plants produce lots of organic molecules that are precursors of ozone, so can make matters worse when mixed with dirty city air. “Oaks, poplar trees – those are no-nos,” he says. And what about rural areas? Although such places are often cleaner, pollutants can have a disproportionate effect here because of their impact on commercially important plants. The solution, says Fuentes, is to plant more flowers around crop fields – in particular, he recommends petunias. These won’t just clean up the pollutants that disrupt plant communication, but will also attract pollinators. If the flowers smell sweet, that’s even better for our human noses. It’s a win, win, win solution. Q Marta Zaraska is a writer based in France

XPIXEL

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IKE stars, snowflakes and blades of grass, sand is one of those things that seems to be in infinite supply. It has been a symbol for quantities beyond counting since ancient times. When the biblical hero Joseph faces an impending famine in the book of Genesis he “stored up grain in great abundance like the sand of the sea, until he stopped measuring it, for it was beyond measure”. Fast forward a few thousand years and things have changed: we are running out of the stuff. “Sand is a lot like oil,” says Jianguo Liu of Michigan State University. “It takes a lot of time to make and it can’t be renewed.” That’s more than a little troubling, for sand is literally the foundation of modern civilisation. It is a crucial ingredient in concrete, bricks, plaster, glass and microchips. What’s more, efforts to mine ever more sand are damaging ecosystems around the world. We can’t do without it, and yet now might be the time to stay our shovels. Increasingly, the world is waking up to the sand crisis and trying to tackle it. Learn to use less sand in a smarter way, and we might just stop this most precious of resources from

slipping through our fingers forever. Think of sand and you probably picture the golden-brown stuff on the beach, which is largely made of silicon dioxide. Yet sand is defined not by its composition, but by the size of its grains, which are smaller than gravel and larger than silt. Roughly speaking, that means between 2 and 0.06 millimetres. Within that range there is a huge variety – from the translucent pink stuff found on dunes in Utah to the black volcanic grains of some Hawaiian beaches. The different kinds suit different applications, but there is one need that dwarfs all others. Between 60 and 75 per cent of the sand we mine goes to sate our hunger for concrete. It is tough, easy to work with and fairly cheap, which is why we use twice as much of it as all other building materials combined: about 30 billion tonnes per year. That is enough to build a wall 27 metres tall by 27 metres wide around the equator, says Pascal Peduzzi at the UN Environment Programme, who wrote a report on the sand crisis in 2014. Concrete is made mostly of sand and its chunkier cousin gravel, with a little cement > 17 February 2018 | NewScientist | 35

AGGREGATE ARMAGEDDON Digging up sand and gravel is causing ecological damage around the globe CORAL BLANKET Dredging sand from the sea floor stirs up a soup of particles. When the sediment settles, it blankets coral reefs and plants, stopping them feeding and photosynthesising. It can also clog marine animals’ gills, suffocating them. DOLPHIN DISRUPTION Dredging has eroded riverbanks on India’s Brahmaputra river. That has upset the ecosystem, threatening the Ganges river dolphin, one of the world’s most endangered freshwater mammals.

11billion tonnes of sand were used to make concrete worldwide in 2010

MARSH MASH-UP Sand mining has degraded marshes in south-east Brazil that are important habitats for the critically endangered São Paulo marsh antwren, a species of bird that was only discovered a few years ago.

SALTED VEGETABLES At the Mekong river delta in Vietnam, sand mining has led to the intrusion of salty ocean water, which damages crops and affects the drinking water supply. COSY MOSQUITOES Pools of water left behind by sand mining are the perfect breeding grounds for mosquitoes. In Iran, these pools are the most common habitats for the larva of the two species that carry malaria. AGGRESSIVE CLAMS Boats used to transport sand may also carry invasive species like the Asian clam. Once introduced into a new area, these clams can outcompete other species and reduce biodiversity.

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94 million cubic metres of sand were dredged from the seabed to build the Palm islands off the coast of Dubai PLAINPICTURE/T.BEHURET

TSUNAMI MAGNIFICATION The impact of the 2004 Indian Ocean tsunami would have been less severe in Sri Lanka, were it not for the removal of dunes that would have protected the coast. Upstream mining has also reduced the amount of sediment reaching the coast, meaning the dunes aren’t being replaced quickly.

and some water mixed in. Most recipes call for large, rough sand grains that bind together well. So, although there may be mountains of the stuff blowing around in the Sahara, for example, those grains are no good for most types of concrete – they are too small and polished round by the wind. The best sources of concrete-compatible sand are river beds, beaches and the near-shore seabed. Sand from the ocean floor works too, although it needs to be laboriously purged of salt and chlorine. Sand mining in such places can ravage the environment. For instance, in the past few years sand pirates have harvested so much

grainy booty from islands in Indonesia that at least 24 of them have disappeared. Much of the sand is shipped to the cramped island state of Singapore, where it is used in land reclamation projects. Meanwhile, there are fears of ecological catastrophe in Indonesia. There are many more stories like this (see “Aggregate Armageddon”, left) and they show we have a serious sand problem. But it is hard to know exactly how serious. Few countries publish how much sand they extract, in part because widespread off-thebooks mining means most don’t know themselves. It is telling that the official

import and export statistics for sand don’t cancel out. One workaround is to tot up how much concrete we use and then track backwards to calculate how much sand we must be using in construction. Alessio Miatto at Nagoya University in Japan used this strategy to estimate that in 2010 the world used about 11 billion tonnes of sand for construction, plus another 11 billion of gravel. Our sand crisis is a classic case of the tragedy

of the commons, where unfettered access to a common resource leads to demand that overwhelms the supply. One logical solution, then, is to set up and enforce rules on how much sand can be mined – but that is easier said than done, especially in remote places. “The real solution is to decrease our need for sand,” says Peduzzi. In effect, that means reducing our use of concrete. Instead of building new apartment blocks, bridges, dams, car parks and more,

SHIFTING SANDS The countries that import and export sand aren’t the ones you might expect, as these selected examples show World sand exports 2016 $947 million

Exporters With its huge land mass and long coasts full of concrete-friendly sand, the US is the biggest exporter. You might have expected it to be somewhere like Egypt, with its sprawling deserts. But fine desert sand isn’t useful for concrete. Instead, Egypt exports smaller quantities that often end up in ceramics. It’s more surprising that Germany and Belgium are  big players. That may be because they are home to large multinational building material companies. Plus, sand is heavy, so it may be cheaper for Germany’s neighbours to import it short distances across the border rather than long stretches across their own country.

Exports

SOURCE: OBSERVATORY OF ECONOMIC COMPLEXITY. 2016

$303 million

US

Germany

Oil well, heal thyself

Belgium

Egypt

0

50 Value (million $)

100

World sand imports 2016 $1.38 billion

Importers Singapore is the world’s largest importer of sand by a country mile. The crowded island state is conducting massive land reclamation projects that require a lot of material. Belgium and Germany are big importers of sand as well as major exporters. That’s probably because, like South Korea and Japan, they import silicon-rich sand for making electronics and glass, and export different sorts. You would think that the United Arab Emirates would have enough sand of its own — but again, it is the wrong sort for concrete. Dubai’s highways and skyscrapers are built with imported sand.

Imports

we can repair those that are already standing. Concrete wear and tear often comes in the form of cracks that weaken structures and allow water to intrude and corrode the embedded metal reinforcements. In the US in particular, many structures are in dire need of repairs. In 2017, the American Association of Civil Engineers awarded their nation’s infrastructure a D+ rating overall, which means it is “at risk”. It found that every day there were 188 million trips across structurally deficient bridges in the country. The UK’s infrastructure received a similar diagnosis when it last had a check up in 2014. To fix the cracks researchers have turned to a surprising ally: bacteria. Hendrik Jonkers at the University of Delft in the Netherlands has developed a spray containing bacteria that produce calcium carbonate, which acts as a filler. In theory, concrete could also come with bacteria mixed in, which could spring into action and heal the building when exposed to the air. But the bacteria can’t fix cracks more than a millimetre wide. Moreover, many species can’t survive for long in concrete – a harsh environment that is about as alkaline as bleach, says Congrui Jin of Binghamton University in New York state.

Singapore

$189 million

Japan

South Korea

United Arab Emirates

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Jin thinks she has a better idea: use fungi instead. They are tougher than bacteria and might provide a better healing additive for concrete. So over the past two years she and her colleagues have conducted the first studies of whether fungal spores can survive in concrete and produce calcium carbonate filler. Screenings have shown up two strains that can pull it off. That isn’t a terrible batting average considering how hostile concrete is, says Jin. However, a fungi-based concrete healing product is still years away. We can’t wait that long, says Mohammed Imbabi, a cement expert at the University of Aberdeen, UK. Take oil wells in the North Sea, he says. There are thousands of them out there, each of which needs to be plugged with concrete at the end of its life. That concrete can’t fail, or else residual oil would seep into the ocean. “The oil majors are desperately looking for solutions,” he says. Imbabi is investigating new species of calcium carbonate-expelling bacteria, which he says offer advantages for oil wells because they can lie dormant for far longer than fungi. He is also looking at microcapsules that could be mixed into concrete. When ruptured they would release chemicals > 17 February 2018 | NewScientist | 37

900,000 SAKIB ALI/ HINDUSTAN TIMES VIA GETTY IMAGES

tonnes of sand were illegally mined around the Indian city of Delhi in one year

SAND MAFIA Unregulated sand mining is a problem the world over – sometimes a violent one Sand is becoming a scarce resource (see main story). It is also heavy and so expensive to transport. That creates an opportunity for local mining gangs; if they can mine sand in areas close to building operations, they can sell it on cheaper than legitimate suppliers. Being part of a “sand mafia” can seem attractive because it is a low-risk, high-profit enterprise that doesn’t require much specialist equipment. It is also a legal grey area. There are no

Lavorgna and Aunshul Rege of Temple University in Philadelphia. Here mafia is the right word. In Italy, sand is simply a new strand of the traditional mafia’s activities. In India, the researchers found that groups are active in 12 of the country’s 29 states. They often mine other commodities such as manganese, which is used to make magnetic metal alloys, and sometimes they use extreme violence to exert control over resources. In June 2015, the

coherent international laws forbidding sand mining. Where local regulations exist, they aren’t always enforced, especially in remote areas. In India, for example, sand mining requires a licence, but some local governments turn a blind eye to illicit operations because they provide an income for otherwise destitute people. The term “mafia” conjures up the idea of a well-organised group that dominates a territory. But that isn’t always appropriate, says criminologist Anita Lavorgna at the University of Southampton, UK. Many groups operate opportunistically in small areas. In some cases, including in Morocco, child labour is involved. We know most about sand mafias in India and Italy, thanks to studies of media reports and court documents by

burned body of a journalist who had been reporting on the sand mafia, Sandeep Kothari, was found near a railway line in Maharashtra. Repeated arrests have done little to check the trade. There are reports of illicit sand mining in Morocco, Algeria, Vietnam, Malaysia and Indonesia, and studies suggest it goes on in at least 70 countries. It’s difficult to get a handle on the size of the illegal sand trade globally. But reports suggest that about 900,000 tonnes of sand were illegally mined around Delhi in a single year. We also know there is a gap between the official figures for sand imports and exports worldwide. That suggests much activity is slipping through the authorities’ hands. “My feeling is that there might be a lot more going on, but it is not known about,” says Lavorgna.

38 | NewScientist | 17 February 2018

that react to produce a filler. Still, even if self-healing concrete becomes a reality, structures will eventually become too badly cracked to repair. Once that happens, we can try a different strategy for reducing sand demand: concrete recycling. This already happens to some crumbling structures, which are cut into blocks and ground into aggregate that can be mixed into concrete in place of sand. The resulting material is even better than regular concrete for low-grade applications like road bases. But regulations prevent it being used in critical structures like bridges. Plus, there is only enough used concrete in worldwide demolition waste to satisfy about 20 per cent of the aggregate needs of the developed world. So if we can’t repair concrete perfectly and we can only recycle so much, can we replace the sand with something else? The Romans made concrete with volcanic ash or a common mineral called pozzolan instead of sand, for example. More recently, we have tried out other options, from sawdust to sediment trapped by dams. These generally involve trade-offs, however. Concrete made with sediment has only a fraction of the strength and durability of concrete made with virgin sand. The same goes for sawdust; you can only replace about a quarter of the sand in concrete before the material’s strength suffers. Perhaps we need to go further and change the way we build entirely. Concrete structures typically have angular shapes with internal steel frames for support. That brutalist approach is hardly frugal in terms of material, but a new wave of architecture might change that.

Blocks by Block The technology that underpins this change is 3D printing. Over the past few years, building firms have developed robots that can print concrete structures quickly and easily. Take San Francisco-based firm Apis Cor, which in 2017 printed the walls of a test house in Russia in 24 hours. Printing concrete allows architects to experiment with innovative building shapes, some of which may use less concrete. But printed concrete is only suitable for certain structures at the moment, says Paulo Monteiro, an environmental engineer at the University of California, Berkeley. That is because the boundaries between layers introduce weak points. Concrete panels cast in a mould don’t

have that problem, but they must be cleverly designed to save space and weight. This is the specialty of architectural researcher Philippe Block at the Swiss Federal Institute of Technology in Zurich. His idea is to build structures from blocks that fit tightly together and support each other in compression. That means the concrete panels can be thinner – which in turn means less sand is needed. The results can be striking. One example is the Armadillo Vault, a 15-metre-wide dome built from some 400 limestone blocks for

“To consume less sand, we may need to entirely change the way we build”

and cooling pipes or wiring. The Block floor is made using a 3D printing process that fuses together successive layers of fine powder to create a final form. This method is highly precise, but the printed materials are relatively weak. A technique called FreeFAB, developed by the European construction firm Laing O’Rourke, could potentially solve that

The Armadillo Vault was made from 400 limestone blocks – and no adhesive

problem. FreeFAB uses a large robotic printer arm that spits out a specialised wax to make detailed moulds that are then used to cast concrete panels. It is a fast process and the material from the moulds can be reused. The method is already being used to produce concrete panels for the Crossrail project, a 100-kilometre railway line being built underneath London. Switching to Block-style concrete building would lower our demand for sand, but lots of real-world iteration and testing must happen before we get to that stage. So perhaps in the meantime it is worth at least trying to firm up the rules on sand mining. A few international conventions touch on sand but they aren’t coherent, says Peduzzi. That is why Liu and his colleagues recently called for a global governance system to be set up for sand. The first crucial step would be to find out how much sand there is and where it lies. Then we could start talking about where extraction can continue and at what level. In other words, we need a global sand budget. “So far research is scattered and fragmented – there’s no complete picture,” says Liu. Developing such a picture is something the international community needs to take seriously, Liu says, and soon. It is time to take our heads out of the sand before it disappears from around them. Q Julian Smith is a writer in Portland, Oregon 17 February 2018 | NewScientist | 39

REUTERS/YULI SEPERI

islands in Indonesia have disappeared after extensive mining by sand pirates

DAVID ESCOBEDO / ESCOBEDO GROUP

the 2016 Venice Biennale arts exhibition (see photo, below). Block designed the structure so it would support itself without any adhesives. It doesn’t have to be limestone, though. One of the group’s more recent projects is a new take on the most pedestrian part of a building, the floor. The Block floor consists of five interlocking pieces of concrete laced with an organic-looking pattern of internal ribbing. Again, the arched panels are designed so that compressive forces hold the floor up, like the ceiling of a cathedral, which eliminates the need for internal steel rods. The result is only 2 centimetres thick and up to 6 metres across, and uses 70 per cent less concrete than a conventional floor. As a bonus, the space saving means there is plenty of room left over to fit heating

24

UPCOMING INSTANT EXPERT EVENTS Saturday 17 February 2018

INSTANT EXPERT MATHEMATICS IN THE REAL WORLD

Discover why the world is chaotic, the secret codes that govern the internet, the statistics that shape our lives and much more. Speakers include Holy Kreiger, James Grime, Chris Budd and three other experts.

Saturday 24 March 2018

INSTANT EXPERT CONSCIOUSNESS

Explore what consciousness is, what are out of body experiences, will we ever build conscious machines and much more. Speakers incude Anil Seth, Karl Friston, Susan J Blackmore and three other experts.

Saturday 14 April 2018

INSTANT EXPERT MENTAL HEALTH

Learn about the many causes of mental illness, what is normal, understanding psychosis, meditation and much more. Speakers include Anne Cooke, Catherine Wikholm, Praveetha Patalay and three other experts.

Find out more and book tickets: newscientist.com/events 10am – 5pm at: Royal College of General Practitioners 30 Euston Square London

CLASSIC EXPERIMENT

Real-life Lord of the Flies Muzafer Sherif’s classic experiment on children is held up as proof that waging war comes naturally to us. But there’s more to this story than meets the eye, reveals Gina Perry

I

N THE summer of 1954, a bus pulled into Robbers Cave State Park in the mountains of rural Oklahoma. The dozen 11-year-old boys on board, all of them strangers to each other, craned to catch a glimpse through the dusty windows of what for most of them was their first summer camp. For a week they explored the park, swam in a creek, and hiked in and around mountain caves. They didn’t know that a couple of days later, a second group arrived, also believing they had the park to themselves. Social psychologist Muzafer Sherif and his team, disguised as camp counsellors, watched each group bond and form its own identity. The two groups named themselves the Rattlers and the Eagles, each with flag, anthem, dress code, leaders and followers, as well as shared rules and standards. “They staked out their territory,” Sherif’s research assistant, O. J. Harvey, told me. “Everything was ‘our’ –

‘our hideout’, ‘our creek’.” The Rattlers felt particular ownership of the baseball field, which they had cleared and marked out. Gradually, each group became aware of the other: when the Rattlers discovered some empty cups in their hideout and heard the sounds of others playing on the baseball field, they began to resent the interlopers. Finally, Sherif brought the two groups together in five days of competition, in everything from baseball to tent-pitching. The winners would be awarded a group trophy and a handsome jackknife for each boy, the losers nothing. From their first interaction on the baseball field, the Rattlers and the Eagles regarded each other with hostility and suspicion, according to Sherif. Throughout the tournament, the adults fanned rivalry between them, covertly stacking the odds against one team, then the other, increasing the tension >

Take two groups of boys, place them in a park, then wind ’em up and let ’em go

17 February 2018 | NewScientist | 41

“The Rattlers, faces smeared with soot, crept up to the Eagles’ cabin in the dark” published, the study is often twinned with the novel. Both involve the transformation of children in the wilderness, a descent into savagery and violence. Sherif described how an observer chancing on the interactions at Robbers Cave would have never have guessed these “disturbed, vicious… wicked youngsters” were in fact the “cream of the crop” in their middle-class home communities. 42 | NewScientist | 17 February 2018

CAROLYN AND MUZAFER SHERIF PAPERS, THE DRS. NICHOLAS AND DOROTHY CUMMINGS CENTER FOR THE HISTORY OF PSYCHOLOGY, THE UNIVERSITY OF AKRON

and keeping the scores neck and neck. Hostilities reached fever pitch halfway through the competition. The Rattlers, faces smeared with soot, crept up to the Eagles’ cabin in the dark. Bill Snipes, now a retired detective but back then one of the Rattlers, recalls the raid: “I climbed through their window and almost fell on one boy. I woke him up and he was not happy. He started swinging at me. We tore their place up. They did the same to us. It was almost like the counsellors were building this animosity.” Days of warring words and fisticuffs followed, with staff only intervening to break things up before anyone got seriously hurt. The violence ended only when the staff engineered a disaster by cutting off the camp’s water supply. In calling for volunteers to help, Harvey hinted that unknown saboteurs may have been at work; that the park had a history of vandalism. All the boys duly volunteered, perhaps fired up by the idea of a common enemy. At the top of the hill behind the mess hall, the two groups found the water line buried beneath boulders and some sacking jammed into the pipes. As the temperature climbed towards 40°C, they realised that they would slake their growing thirst sooner if they worked as a single team to clear the obstructions. This saw the group boundaries blur and, in a series of problem situations devised by Sherif over the final week of the three-week study, dissolve. By the time the boys returned home – this time in a single bus – their antagonisms had been forgotten. They were a cohesive group who sang Oklahoma! with gusto. Sherif’s Robbers Cave study is remembered less for its happy ending than for its startling demonstration of just how quickly animosity can develop between people who have no reason to hate each other – an indictment of human nature. Carried out in the year that William Golding’s Lord of the Flies was

The youngsters had no idea they were part of a psychological experiment

But the scientist’s and novelist’s views of human nature couldn’t have been more different. For Golding, “man produces evil as a bee produces honey” and his novel was, he said, “an attempt to trace the defects in society back to human nature”. For Sherif it was the other way round: people were inherently good and it was the environment – economic, political, social – that set groups competing against each other, fostering rivalry, prejudice and violence. If Golding was a pessimist, Sherif was an optimist: he thought you could foster peaceful coexistence between warring tribes by changing the environment. The roots of Sherif’s experiment lay far from rural Oklahoma. Sherif had arrived in the US from his native Turkey in 1929 at the age of 23, as part of a wave of young intellectuals sent abroad by the new government of Mustafa Kemal (later called Atatürk) to study and bring back the tools for shaping a new nation. After a stint at Harvard University, Sherif ended up at Columbia University in New York City.

When Sherif arrived, the city was in the grip of the Great Depression. He was appalled by the suffering of thousands of unemployed and homeless people who flooded the streets. At rallies he heard of the antagonism and racism between working people competing for jobs and housing, and passionate calls for the poor and unemployed to unite for radical social change. Moved by the disenfranchised and what he saw as the cruelty of the capitalist system, Sherif gravitated towards a group of intellectuals who thought that communism offered a framework for understanding the chaos of the Great Depression and the rise of fascism, racial prejudice and anti-Semitism. In his first book in 1936, he blamed a “competitive individualistic bourgeois society” for creating frictions between different social classes, believing that “the classes themselves must be eliminated”. But on his return to Turkey in 1937, Sherif found such views unwelcome. In 1944, he was swept up in the first of a series of anticommunist purges and was briefly jailed, before his influential family secured his release. Disenchanted, he appealed to friends

in the US to help him find a job, and soon after left Turkey for Princeton University. But in his years away from the US, and cut off by the second world war, the country had changed; the vibrant left-wing intellectual scene Sherif had been part of in New York had dissipated. Sherif’s idealism was undimmed: in a 1947 book he co-wrote, he expressed sympathy for Marxism and admiration for what he saw as the benefits of Russian collectivism over the capitalist culture of the US. With his ideology clear, he set about devising an experiment to “prove” that collectivism trumps competition.

In the conflicts planned by Muzafer Sherif (below), the tribes came up with flags and mottos

Fight snub In 1949, 1953 and 1954, Sherif conducted summer-camp experiments in three locations. In 1949, the two warring tribes united following the introduction of a third group, a common enemy. In 1953, the boys all mixed as one large group for a day before being separated into teams. Sherif wanted to show he could turn friends into enemies. It backfired: the boys mutinied against the staff, whom they accused of trying to make them fight. Sherif approached the final experiment “with a definite script in mind”, says Harvey, and at Robbers Cave he finally got the results he wanted. During those first camp studies, the themes Sherif was researching – of friends and foes, loyalty and betrayal – were being played out in his own life. The political climate that drove him from Turkey was making itself felt in the US as the cold war began to bite. In 1949, he took a job at the University of Oklahoma just before the state legislature launched a committee to investigate communism and required that state employees and university staff swear loyalty to the US. In signing the oath, Sherif swore he had not been part any communist-leaning groups in the previous five years. As a foreign-born scientist working on navy-funded research, he was considered a security risk and FBI director J. Edgar Hoover launched an investigation into him. FBI agents interviewed Sherif’s mentors and colleagues, librarians and landladies, shopkeepers and administrative staff who had known him in the US, as well as some who had known him in Turkey. One so-called friend told investigators that Sherif “would have no hesitation in providing all the information he might possess to the Russians”. But no one else repeated the claim, and Sherif was cleared. This climate of fear shaped the way Sherif presented his work. Early on, describing the

way the animosity erupted between the two groups, Sherif wrote that the boys’ behaviour reflected the dynamics of a competitive society that divided people into the “haves and have-nots”. In the McCarthyite climate of the time, this could be read as suspiciously pro-communist, and between the first draft of his 1949 summer camp study and its final report, Sherif distanced himself from his political past. He also began to play down any deliberate manipulation that the researchers engaged in to escalate friction between the groups or engineer the environment to gain specific results. From the final draft of his 1949 report through to his book The Robbers Cave Experiment: Intergroup conflict and

cooperation in 1954, Sherif crafted a narrative in which social classes became “groups”, political ideologies became “environments” and the researcher performing feats of social engineering to demonstrate his theory became invisible. In reality, however, Sherif’s team took increasingly active roles in the three experiments. Archive material reveals how at Robbers Cave, for example, they encouraged the Eagles and Rattlers to retaliate against each other, accompanying the boys on raids. Modern research ethics mean that such an experiment cannot be repeated today, so we may never know how a Robbers Cave scenario would unfold with no adults to stoke factionalism. Since it was conducted, the Robbers Cave study has become a classic in social psychology and beyond, referenced in developmental psychology, neuroscience and in evolutionary explanations of discrimination, prejudice, conflict and war. But in accepting Sherif’s politically neutral account of his own research, it is easy to overlook the amount of social engineering involved and what it says about the power of manipulation. In a world in which racism and tribalism are on the rise, the real lesson of Robbers Cave is not that humans are hardwired for war, but that we should look beyond warring factions and behind the scenes, to ask whose interests – political, national, corporate – are being served by division and conflict. ■ Gina Perry is a psychologist and writer in Melbourne, Australia, and author of The Lost Boys: Inside Muzafer Sherif’s Robbers Cave experiment (Scribe), out this April 17 February 2018 | NewScientist | 43

CULTURE

The inside story of blood The revolutionary William Harvey deserves his show, says Simon Ings under its own volumetric pressure. Heaven help you if you made too much of the stuff. Luckily, physicians were on hand to release this disease-inducing pressure through bloodletting. It sounds daft now, but clues back then that something quite different was going on were sparse and controversial. The 16th-century physician Andreas Vesalius had puzzled over the heart. If, like every other organ, it fed on blood produced in the liver, why were its walls so impenetrably hard? But even this towering figure, the founder of modern anatomy, decided that his own observations had to be wrong. It was Hieronymus Fabricius, Harvey’s teacher in Padua, Italy, who offered a new and fruitful

AFFECTION and delight aren’t qualities you would immediately associate with an exhibition about blood flow. But Ceaseless Motion reaches beyond the science to celebrate the man – 17th-century physician William Harvey – who, the story goes, invented the tradition of doctors’ bad handwriting. He was also a benefactor: when founding a lecture series in his own name, he remembered to bequeath money for the provision of refreshments. It is an exhibition conceived, organised and hosted by the UK’s Royal College of Physicians, whose 17th-century librarian Christopher Merrett described how to make champagne several years before the monk Dom Pérignon began his experiments. Less happily, Merrett went on a drinking binge in 1666, and let Harvey’s huge book collection burn in London’s Great Fire. The documents, seals and signatures that survived the flames despite Merrett’s neglect take pride of place in an exhibition that, within a very little compass, tells the story of one of medicine’s more important revolutionaries through documents, portraits and some deceptively chatty wall information. Before Harvey’s 10 years of intense, solitary study bore fruit, physicians thought blood was manufactured in the liver and then passed through the body Harvey’s demonstration rod was capped with a silver ferrule 44 | NewScientist | 17 February 2018

JOHN CHASE/ROYAL COLLEGE OF PHYSICIANS

Ceaseless Motion: William Harvey’s experiments in circulation, the Royal College of Physicians, London, to 26 July

tack when he mapped “the little doors in the veins” that, we know now, are valves maintaining the flow of blood back to the lungs. Within 30 years, Harvey’s realisation that blood pressure is controlled by the heart, and that this organ actively pumps blood around the body in a continuous circuit, had

“Harvey, who founded a lecture series in his name, remembered to bequeath money for refreshments” overturned the teachings of the 2nd-century Graeco-Roman physician Claudius Galen in European centres of learning. The new thinking also put close clinical observation at the heart of a discipline that had

traditionally spent more time on textual analysis than on examining patients. The exhibition is housed in a building designed by Denys Lasdun. This celebrated modernist architect was so taken by Harvey’s achievements that he designed the interiors as a subtle homage to the human circulatory system. With the royal college now celebrating its 500th birthday, its institutional pride is palpable, but never stuffy. As one staff member told me, “We only started talking about ourselves as a ‘Royal’ college after the Restoration, to suck up to the king.” Those who can visit should be brave and explore. Upstairs, there are wooden panels from Padua with the dried and salted circulatory and nervous systems of executed criminals lacquered into them. They are rare survivors: when pickling methods improved and it was possible to provide medical students with threedimensional teaching aids, such “anatomical plates” were discarded. Downstairs, there are endless curiosities. The long sticks doctors carried in 18th-century caricatures were clinical instruments – latex gloves didn’t arrive until 1889. The sticks’ silver ferrules contained miasma-defeating herbs and, sometimes, phials of alcohol. None of them are as handsome as Harvey’s own demonstration rod. But if a visit in person is out of the question, take a look at the royal college’s new website, launched to celebrate half a millennium of institutional conviviality and controversy. You will have to provide your own biscuits, though. ■

For more books and arts coverage, visit newscientist.com/culture

From wildlife to street life Nature can inhabit the city, but only if we help, finds Matthew Cobb Schilthuizen, a professor of biodiversity at Leiden University in the Netherlands, doesn’t dismiss attempts to conserve species in the wild or protect wilderness. As an experienced researcher in tropical biology and with a deep love for the natural world, he understands the importance of maintaining the remaining wild areas. In a moving coda, he describes his sadness at

Darwin Comes to Town: How the urban jungle drives evolution by Menno Schilthuizen, Quercus

“Schilthuizen describes the wonders of what he calls human-induced rapid evolutionary change”

MOMENT/GETTY

EVOLUTIONARY biologist Menno Schilthuizen is clearly a glass-halffull kind of guy. In his resolutely optimistic book Darwin Comes to Town, he takes us on a global tour of how nature is responding to massive urban expansion, and finds much that is good. Faced with our alteration of the planet and its climate, in particular through a toxic mix of increased urbanisation and highly intensive farming, Schilthuizen’s pragmatic and balanced response is to look for the positives. He finds these in the very places where most of us now live: cities. Urban sprawl, he proclaims, creates spaces for those organisms able to resist the concrete, the noise, the lack of greenery and the effects of chemical and light pollution. In his thought-provoking Approve or not, cities too are book, Schilthuizen describes the now part of the natural world wonders of what he calls humaninduced rapid evolutionary change, as animals and plants recently been observed, while the adapt their bodies and habits to significance of the physical and the new urban terrain, creating behavioural changes shown by new ecological niches. urban blackbirds in Europe is Some of these examples have only just being appreciated. been studied for a long time: the Schilthuizen cleverly uses rise and fall of blue tits pecking at examples of urban biodiversity British milk-bottle tops was first to explore the central concepts noted in the 1930s, and has now of behavioural ecology, from virtually disappeared, along with ecosystem engineers (ants the doorstep deliveries of full-fat and humans), through island milk that made it possible. Other biogeography (as true on adaptations, such as that of the roundabouts as on oceanic isles) now pigeon-eating catfish of Albi to honest signalling and sexual in southern France, have only selection. These ideas are

explained simply, often supported by the words of the scientists directly involved. With care, Schilthuizen explores whether the changes he describes are in fact examples of evolution – changes in genes – or whether they are cases of learning or of the fashionable, but rarely demonstrated, inherited non-genetic changes known as epigenetics. The rigorous and stimulating discussions of how we can distinguish between various causes of change, and what their long-term implications are, help make the book required reading.

returning to the semi-wild edgeland bogs of his Rotterdam childhood to find them covered with neat housing estates. But barring a catastrophe that decimates the human population, he emphasises that we – and nature – are going to have to make do with an urbanised planet. And the urban spiders and plants and birds and microbes he describes give some reason to be optimistic. As a glass-half-empty kind of guy, at least when it comes to the future of biodiversity, I was particularly pleased by the final section covering four ways we can encourage urban biodiversity: let wild organisms survive, don’t eliminate non-native species, preserve pristine wild areas around cities and monitor urban biodiversity using apps and citizen science. If we are careful, Schilthuizen’s vision of a rich, urban ecology may come to pass. I hope for all our sakes it does, because the alternative is deeply alarming. ■ Matthew Cobb is a zoologist at the University of Manchester in the UK 17 February 2018 | NewScientist | 45

CULTURE

Got our eyes on you! Absurdity shapes a new show on data and culture, finds Simon Ings [JOYCAT]LMAO, Open Data Institute, London, throughout 2018

CEILING CAT BY EVA AND FRANCO MATTES. PHOTOGRAPH BY THEO MCINNES/ODI

ON Friday 12 January 2018, curators Julie Freeman and Hannah Redler Hawes left work at London’s Open Data Institute confident that, come Monday morning, there would be a few packets of crisps in the office. Artist Ellie Harrison’s Vending Machine (2009) sits in the ODI’s kitchen, one of the older exhibits acquired over the institute’s fiveyear programme celebrating “Data as Culture”. It has been hacked to dispense a packet of salty snacks whenever the BBC’s RSS feed has a news item containing financial misfortune. No one could have guessed that, come 7 am on Monday, Carillion, It had no time at all for Wilfred the UK government’s services Owen: “Froth-corrupted” (Dulce contractor, would have gone into et Decorum Est) earned £0.00. liquidation. There were so many You can, of course, reverse this packets in the hopper no one game and ask what happens to could open the door, say staff. people when they over-interpret Such anecdotes are the stuff of machine-generated data, seeing this year’s show, as humour and patterns that aren’t there. This is absurdity are harnessed to ask big what Lee Montgomery has done questions about internet culture, with Stupidity Tax (2017). In an privacy and artificial intelligence. effort to understand his father’s Looking at the world through mild but unaccountably secretive algorithmic lenses may bring gambling habit, Montgomery occasional insight, but what really “Seeing the world through matters here are the pratfalls as, algorithmic lenses may time and again, our machines bring insight, but what misconstrue a world they cannot matters are the pratfalls” possibly comprehend. In 2017, artist Pip Thornton fed famous poems to Google’s has used a variety of data analysis online advertising service, techniques to try to predict the Google AdWords, and printed the UK National Lottery. The sting monetised results on till receipts. in the tale is the installation’s The framed results value the word associated website, which implies “cloud” (as in I Wandered Lonely as (mischievously, I hope) that the a Cloud by William Wordsworth) whole effort has driven the artist highly, at £4.73, presumably ever so slightly mad. because Google’s algorithm was Watching over the whole show – dreaming of internet servers. literally because it is peeking 46 | NewScientist | 17 February 2018

through a hole in a ceiling tile – is Franco and Eva Mattes’s Ceiling Cat, a taxidermied realisation of the internet meme, and a comment on the nature of surveillance beliefs. “It’s cute and scary at the same time,” the artists say, “like the internet.” Co-curator Freeman is a data artist herself. You may have seen her naked mole rat surveillance project at last year’s New Scientist Live. The 7.5 million data points acquired by the project are now keeping network analysts busy at Queen Mary University of London. “We want to know if mole rats make good encryption objects,” says Freeman. Their nest behaviours might generate true random numbers, handy for data security. “But the mole-rat queens are far too predictable... Crisp?” Through a mouthful of salt and vinegar, I ask Freeman where her playfulness comes from. And as I suspected, there is intellectual steel beneath: “Data is being constantly visualised so we can

Ceiling Cat is a comment on our beliefs about surveillance

comprehend it,” she says, “and those visualisations are often done in a very short space of time, for a particular purpose, in a particular context, for a particular audience. Then they acquire this afterlife. All of a sudden, they’re the lenses we’re looking through. If you start thinking about data as something rigid and objective and bearing the weight of truth, then you’ve stopped discerning what is right and what is wrong.” Freeman wants us to analyse data, not abandon it, and her exhibition is an act of tough love. “When we fetishise data, we end up with what’s happening in social media,” she says. “So many people drowning in metadata, pointing to pointers, and never acquiring any knowledge that’s deep and valuable. There should be some words to express that glut, that need to roll back a little bit. Here, have another crisp.” ■

INFINITY AND BEYOND Your ultimate guide to mathematics =HURLQĆQLW\ZRQGHUQXPEHUVSUREDELOLW\DQGVWDWLVWLFV V\PPHWU\DQGUHDOLW\FRPSXWDWLRQDOFRPSOH[LW\PDWKV DQG\RXUEUDLQDQGPXFKPRUH %X\\RXUFRS\IURPDOOJRRGPDJD]LQHUHWDLOHUVRUGLJLWDOO\ )LQGRXWPRUHDWnewscientist.com/thecollection

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EDITOR’S PICK

Everything put together falls apart, unless we have a vision

From Linda Dawe, Chesham, Buckinghamshire, UK As a scientifically curious artist I was interested to read Laura Spinney’s article on the possible collapse of Western civilisation as we know it (20 January, p 28). But what would earlier writers have made of it all? Well, the writer Rudyard Kipling said:

“Cities and Thrones and Powers / Stand in Time’s eye, / Almost as long as flowers, / Which daily die.” On our inability to deal with our own personal contribution to impending doom, he wrote: “We had a kettle: we let it leak: / Our not repairing it made it worse. / Now we haven’t had any tea for a week… / The bottom is out of the Universe.” But the last word goes to another poet and lyricist, Paul Simon, summing up all human history in his song Everything put together falls apart.

From Paul G. Ellis, Chichester, Hampshire, UK Spinney’s article and your Leader (20 January, p 5) provide a useful underpinning for thoughts that must be haunting many of us who have paid attention to world news in the last

decade. What they omit, however, is a vision or ideas that might inspire a great majority of humanity toward a long-term consensus. Though Marxism, for example, has manifestly failed – arguably through its divisiveness – its early spread did show the possibility of inspirational ideas having powerful and widespread influence. Surely, now, attempts should be made to counter pessimism by trying to work out and promulgate some inspirational vision of humanity’s future to which most governments, organisations and populations might be able and willing to subscribe. It won’t be easy to find common ground between authoritarian and democratic governments, nor across sectarian and other divides – but that just indicates how far-seeing such a vision would need to be.

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Several ways we could handle the heat From Duncan Cameron, Brighton, East Sussex, UK John Pickrell suggests ways to stay cool in heatwaves (20 January, p 36). Before Saddam Hussein came to power, I lived in Basra in southern Iraq. It was said to be the hottest major city on the planet, with both high humidity and 40°C summer temperatures. The modern city of cement and brick with asphalt boulevards was almost uninhabitable in summer without air conditioning. The old city was better, with closely packed light wooden structures in narrow alleys. But the prize belonged to the people of the Mesopotamian marshes to the north, who probably knew more than anyone about natural climate amelioration. They had lived in buildings adapted to the

Could you help transform a life? It costs $50 to send a child to a UWS school for a whole year. That’s less than $1 per week. hŶŝƚĞĚtŽƌůĚ^ĐŚŽŽůƐĐƌĞĂƚĞƐĞĚƵĐĂƟŽŶĂůŽƉƉŽƌƚƵŶŝƚLJ for children living in the world’s poorest regions. We are driven by our global mission to help reach children that ĚŽŶŽƚƌĞĐĞŝǀĞĞǀĞŶƚŚĞŵŽƐƚďĂƐŝĐĞĚƵĐĂƟŽŶ We have now reached over 15,000 previously outŽĨƐĐŚŽŽůĐŚŝůĚƌĞŶĨƌŽŵƌĞŵŽƚĞĐŽŵŵƵŶŝƟĞƐĂĐƌŽƐƐ Cambodia, Myanmar and Nepal, thanks to the support of people like you. Please help us to reach our target of 50,000 children by 2019. Every penny, pound, cent or dollar donated goes towards helping girls and boys in marginalised and ƉŽƐƚĐŽŶŇŝĐƚĐŽŵŵƵŶŝƟĞƐ www.unitedworldschools.org I @teamuws| [email protected]

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“It depends on the expectation of what is ‘comfortable’, doesn’t it?” Gemma Pearce responds to the idea that it is impossible to live comfortably without trashing Earth (10 February, p 10)

climate since Babylonian times. These were made of bundles of reeds that didn’t absorb heat, with open entrances that ensured a flow of air. They were delightful to sit in. Is it possible to envisage a postanthropogenic climate change architecture that learns from the experts of the past? From Anthony Wheeler, Mackay, Queensland, Australia More ways to keep cool in our increasingly hot climate include building houses on stumps 2 metres high to allow cooling air to circulate underneath. This, along with high ceilings that allow hot air to rise away from the occupants, is how old Queensland houses were built. Chimneys can also help by sucking warm air out of a structure by Bernoulli’s principle. Finally, recessing the house into the

ground can keep it cool – or even burying it all, as in the town of Coober Pedy in South Australia. From James Willis, Alton, Hampshire, UK What about solar-powered air conditioning? It is impossible for any form of air conditioning to reduce net global warming, but solar power would surely be an improvement on the fossil fuel status quo, especially in sunny places with dispersed populations such as Pickrell’s own Australia. It would be interesting to see a quantification of just how great this improvement might be. Clearly the energy required for manufacture, installation and eventual dismantling and recycling of the units would have to be taken into account, although much of that might come from renewable sources. Even if the benefit to the global energy

balance is smaller than we hope, the immediate, local benefits of zero running costs and immunity to grid outages would surely make such systems attractive. From Guy Cox, Sydney, Australia Pickrell writes: “The creation of air-conditioned public refuges is another option that was discussed widely during last summer’s heatwave here in Australia.” But they already exist, are numerous and nobody is more than a short drive from one. They are called shopping malls and are very widely used for just that purpose, not least in this summer’s extreme heatwave. Thousands of square metres of air-conditioned space, interesting shops, play areas for children, food outlets, cinemas… What government refuge could possibly compare with that?

Quantify the economy in physical terms, please From Jane King, Edinburgh, UK Bryn Glover is undoubtedly correct that money has absolutely no intrinsic value (Letters, 16 December). It was this that led us at the University of Edinburgh to look at the economy and the numerous interactions within it using not money, but a physical unit of account: the energy embodied in goods and services as they are brought to the market. We summarised our findings in the book Not By Money Alone. Our aim wasn’t to dislodge conventional economic ways of thinking, but rather to identify the physical boundaries within which economies are constrained to operate: even economists cannot escape thermodynamic limits. Not surprisingly, the approach >

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was received unenthusiastically by traditionalists; it attracted considerable interest otherwise.

or weak seemed to manage this very well, in spite of having only one leg for propulsion!

If we fall down, here’s how to get up again

Don’t deny me pain relief for others’ problems

From Ginny Craig, Knaresborough, North Yorkshire, UK Joan Zealey writes of her mother’s failure to get up again after falling (Letters, 27 January). I worked as a specialist physiotherapist for people who had had a leg amputated. One of the criteria for discharge from hospital was that everybody was shown how to get up from a fall. This involved lying still for a while to get over the shock of the fall, then rolling onto their side and pushing up into a sitting position. Once sitting, they were shown how to “bum shuffle” backwards using their hands for support and the remaining leg for propulsion. If they had stairs, they bum shuffled to the bottom of the stairs and raised themselves backwards, step by step, until they could use the bannisters to pull themselves into standing. Surprisingly, even the very old

From Hilary Gee, Cartmel, Cumbria, UK I do understand that, as Andrew Kolodny says, there is a problem with the over-prescription of opioids and that many people could manage their pain with less powerful versions (13 January, p 35). Even a mild pain gets very wearing and hampering if it never goes away. And if it does persist, as with the chronic arthritis I have, becoming addicted to painkillers is more or less irrelevant, since I continue to need relief anyway. Though Kolodny doesn’t want to ban painkillers, anyone with chronic pain will understand the fear of being denied relief because of other people’s problems. The pain is real, it may never go away, and nor will the need for effective drugs. Perhaps research into safer but equally effective pain treatments might be the best cure for the addiction crisis. And

TOM GAULD

controlling the drug companies, of course. They have been allowed to over-sell into the ludicrously commercial US medical system.

Are we alone in the universe or not? From John Harvey, Rodmell, East Sussex, UK Dirk Schulze-Makuch and William Bains make a very good case for expecting life, even complex life, to have evolved and proliferated across the galaxy (13 January, p 22). But they argue that failure so far to find evidence of extraterrestrial technology suggests the evolution of technological civilisations may prove a real stumbling block. There is another possibility. Our own galaxy has been around for over 10 billion years, more than twice as long as the solar system. There is plenty of time for advanced civilisations to have evolved elsewhere. Assuming a random distribution across time of many evolutions, most would be millions of years ahead of us. Such super-beings wouldn’t have sat around waiting to be discovered by earthlings. They

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would have discovered us a long time ago. I think they would find a way of subtly hinting to us that Earth’s civilisation wasn’t as unique as we thought. From Derek Hough, Chalford, Gloucestershire, UK We currently have little idea how even simple life could have evolved from inert chemicals, so we must not get ahead of ourselves when discussing types of life that could exist elsewhere in the universe. It seems to me that a universe with a single occurrence of life is almost infinitely more probable than a more ordered universe in which life is slightly more commonplace. Rest assured, we are alone.

A most interesting thing about earwax From John Dick, Claremont, California, US Christie Wilcox, describing the secrets of earwax, didn’t mention a most interesting thing about our ears and earwax that helps to explain many of the issues discussed (23/30 December 2017, p 67). This is the fact that the skin in the ear canal grows outwards, just as our fingernails do, and at a similar rate. This carries the wax outwards to be eventually cleared, and results in the waxy historical record Wilcox refers to.

For the record Q The inconstant moon: its orbit is inclined 5 degrees to the ecliptic, the plane of Earth’s orbit around the sun (28 November 2015, p 13).

Letters should be sent to: Letters to the Editor, New Scientist, 25 Bedford Street, London, WC2E 9ES Email: [email protected] Include your full postal address and telephone number, and a reference (issue, page number, title) to articles. We reserve the right to edit letters. New Scientist Ltd reserves the right to use any submissions sent to the letters column of New Scientist magazine, in any other format.

54 | NewScientist | 17 February 2018

SIGNAL BOOST

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FEEDBACK

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demonstrated that more attractive people are treated more favourably in society, and the authors hypothesise that this leads them to have difficulty in appreciating the hardship that others face. In the same journal, Niclas Berggren and his colleagues note that this also applies to politicians. In fact, the pattern appears so ingrained that, in the absence of other information, voters will assume that the attractive candidate is the conservative one. Finally, a scientific discovery that narcissistic despots can cheer about.

PAUL MCDEVITT

“IF PEOPLE no longer easily trust their human priests, and there is less of religious community life, could they trust a robot priest?” Stanford University’s Cindy Mason discussed the case for a mechanical minister at a recent conference on ethics and AI held in New Orleans, Louisiana. Noting that revelations around sexual abuse in the Catholic church had diminished trust in priests, Mason explored the role that costumes had on shaping public reactions to robots. A robot fashion show at a Nordstrom department store in 2015 demonstrated that the same robot dressed in different outfits – bride, superhero, “frilly girrly” and others – elicited different reactions, and people were more likely to ask about the robot’s role than its hardware or software. It’s not clear to us whether robot priests would be rehabilitating the image of robots or priests, but we note that as well as a stint as a shopping assistant, the Pepper android built by Softbank Robotics has also turned its hand to ministering Buddhist funerals.

In 2011, the Engineering and Physical Sciences Research Council published guidelines about ethical robots, the fourth of which states that machines “should not be designed to exploit vulnerable users by evoking an emotional response or dependency”. Mason recommends an addendum: that robots should be designed so that their appearance matches their function. In other words, clothes maketh the man – and the machine.

GOOD-looking people are more likely to identify as politically right wing, according to a recent study published by the Journal of Public Economics. Rolfe Peterson and Carl Palmer looked at two historical data sets that include information about political beliefs and looks. For one, interviewers were instructed to rate the respondents “from 1 (homely) to 5 (strikingly handsome or beautiful)”. The results show that more attractive people tended to gravitate toward conservative political opinions. It’s well

French media reports that annual sales of Nutella weigh in at “almost as much as the Empire State building”. Lynn Holman asks “Why can’t they use elephants like everyone else?” 56 | NewScientist | 17 February 2018

READER Derek Woodroffe is left in the dark by roadworks on the A52 going in to Derby. He says there is a sign there telling drivers that due to the roadworks, the street lighting isn’t working. “Although it was daytime, so I probably didn’t need the lighting, it did occur to me that each of the lamps has a large bright indicator showing that the light is working,” says Derek. The lack of light from the lamps at night would probably tell me that they were out of service, he says, “so the sign feels rather redundant”. He notes the sign itself wasn’t illuminated, “although I’m not sure if that would make the sign more or

gannets and accompanied by solar-powered speakers playing their calls, were installed in the hopes of encouraging the birds to start a colony. However, when three real birds arrived recently, Nigel chose to ignore them, preferring the company of his stony companions, and died soon after.

SCIENTISTS are reviewing everyday items that prove useful for research, using the #reviewforscience hashtag on Twitter. The trend was inspired by an Amazon review for tea strainers left by “John”, who noted that the spherical mesh cage was perfect for holding ants. We find a 10-speed batteryoperated body massaging wand is just right for luring spiders out of their dens. And another entomologist waxes lyrical about Keebler Pecan Sandies Cookies:

A PERFECTLY aged Howard Bobry writes: “I must respectfully disagree with both Feedback and reader Colin Jacobson regarding the ageing effects of birthdays” (20 January). He says that as someone born on 29 February, “I can assure you that my having had only 17 birthdays has not limited my ageing, nor has this paucity hastened my demise (yet)”.

“You will not find a more convenient and attractive field bait for myrmicine ants. No mess, no fuss, and the light color allows easy following of foraging worker ants back to their nest.” Clear nail polish proves useful both for “sealing coverslips onto freshly stained slices of brain” and essential first aid for jungle fieldwork, where you can use it to seal botfly wounds in the skin to prevent the maggot beneath developing. Who said science wasn’t glamorous?

THE Guardian reports the death of Nigel, a male gannet that spent five years alone on Mana Island in New Zealand, trying to court decoys placed there by conservationists. The 80 concrete replicas, painted to look like

You can send stories to Feedback by email at [email protected]. Please include your home address. This week’s and past Feedbacks can be seen on our website.

less useful”.

Last words past and present at newscientist.com/lastword

THE LAST WORD Sting in the tail Mosquito bites frequently induce a sharp sting in people and some animals, with severe evolutionary consequences for the mosquito when it gets swatted. Are any mosquitoes evolving with delayed-action stings or reduced sting secretions so that they can drink blood without the threat of imminent death?

QMosquitoes have been around since the Jurassic period and probably evolved to feed on dinosaurs. Although we humans consider ourselves to be the most important animal on Earth, from the mosquito’s point of view we are somewhat irrelevant because they have evolved to feed on specific hosts. However, much like fleas, they will not pass up a meal if one is available from the wrong host. I can make a useful comparison with my experience of the tiger mosquito, Aedes albopictus. This Asian mosquito has recently invaded Europe and, to my chagrin, it took up residence in my locality last summer. Its bite is the most unpleasant I have ever experienced. It is simultaneously painful and itchy and causes a small bump to form, so presumably it’s not particularly adapted to humans. In fact, it will feed on any suitable host – bird or mammal. It attacks in swarms in full sunshine and can penetrate socks, jeans and T-shirts with ease. It is solenophagic, which means it thrusts its stylets directly into

We pay £25 for every answer published in New Scientist. To answer a question or ask a new one please email [email protected]. Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address. You can also send questions and

blood vessels and seems to take just a matter of seconds to be fully fed. You may swat some, but not all, especially if they are in the middle of your back, and often not before they have had time to feed. Any survivor can lay a couple of hundred eggs and mate up to four times in its lifetime. The fact this mosquito is known to spread dengue and chikungunya means it must manage to feed on at least two victims, so it does not seem to be compromised by its painful bite. Then again, those odd one or two mosquitoes that do find their way into my bedroom at night, when A. albopictus is not active, seem to be able to feed on me without leaving a trace. This morning I woke up with an itch behind my left knee. So some have already evolved to feed on me without me noticing, or at least without me noticing enough to try and swat them. Terence Hollingworth Blagnac, France QYour correspondent has confused bites and stings. A sting usually refers to a toxin injected into a host by a specialised organ, the organ itself or the resulting sensation, whereas a bite is performed by mouthparts. Moreover, “bite” isn’t the best way to describe mosquitoes’ behaviour, as it implies the action of toothed jaws. Mosquitoes don’t sting; rather, they pierce their long mouthparts (proboscis) through the host’s skin. The proboscis comprises two tubes:

answers to The Last Word, New Scientist, 25 Bedford Street, London, WC2E 9ES. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format and at any time in the future. All unanswered questions and previous questions and answers are at newscientist.com/lastword/

one to suck up blood, the other to inject saliva. Only female mosquitoes bite, because they require protein from blood for egg production. Nonetheless, female mosquitoes are likely to have undergone selection for an unnoticeable bite, as your correspondent supposes. As well as anticoagulants, mosquitoes do inject mild painkillers into the host via their saliva. Sam Buckton Chipperfield, Hertfordshire, UK

Heated debate In your article about housework (“Germ Warfare”, 14 January 2017), you said that after washing dishes we should “rinse with plenty of water, preferably hot”. Why hot? Wouldn’t it save money if they were rinsed with the cold water that comes directly from the mains?

QWhile washing-up liquids come in various fragrances – lemon for instance – that might flavour a sauce, unless you relish the taste of even unscented detergent then it is best to rinse. “Preferably hot” does imply that using cold water remains an option, but there is one big downside to cold – and it is personal. Water straight from the mains can be icy cold and prolonged contact with it can be painful. So hot water is more comfortable. Second, it is less viscous, and more readily runs from the tap and off the dishes

with the soapy suds. It also happens to be less dense, so you might even use less water and save money this way. Third, although dish detergents work by binding with both water and grease to form a soluble emulsion, the emulsion still behaves much like its components. Like the neat detergent, it is more viscous and less soluble in cold water. And like the plain fat, it can congeal when cooled – especially with fats that are solid at room temperature. Rinse with cold, therefore, and your freshly cleaned dishes could end up retaining an invisible film of grease, or the cold conjugate could start congealing to gum up the waste pipe. Finally, hot water warms the dishes, encouraging any residual moisture to evaporate and dry off more quickly. The precise temperature at which these effects start to make a difference isn’t clear. Just don’t expect me to do the research – it would be like watching plates dry. Len Winokur Leeds, UK

This week’s question HOT SAUCE

Why is there no insulation for saucepans? Or around kitchen sinks or bathtubs? Is it difficult and expensive, or just a lazy tradition inherited from wasteful innocent times? Peter Gleeson Axedale, Victoria, Australia