April 13 –19, 2019 New Scientist

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MEET YOUR NEW COUSIN

Another ancient human discovered

GOING INTERSTELLAR

The mission to visit an alien solar system

WEEKLY April 13 –19, 2019

THE MYSTERY LIFE INSIDE US Our microbiomes contain life forms we never knew existed

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PLUS BLACK HOLE FINALLY PICTURED / FIRST GM REPTILES / THE FOUR-DAY WEEK / COLOMBIA’S ASTOUNDING BIODIVERSITY

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Origin story of world’s largest stone circle

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SECRETS OF AVEBURY

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Humanity will need the equivalent of 2 Earths to support itself by 2030.

People lying down solve anagrams in 10% less time than people standing up.

About 6 in 100 babies (mostly boys) are born with an extra nipple.

60% of us experience ‘inner speech’ where everyday thoughts take a back-and-forth conversational style. We spend 50% of our lives daydreaming.

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Meet your new cousin Another ancient human discovered

32 Going interstellar The mission to visit an alien solar system

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News 6

THIS WEEK First picture of a black hole. UK government wants new internet laws. Bombing an asteroid

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NEWS & TECHNOLOGY Surgery over the internet. Chronic fatigue treatment fails trial. Snowflakes heat the Arctic like a blanket. New species of human. The origins of Avebury. Face scans could reveal rare conditions. Ancient toothache. DeepMind’s AI fails maths tests for kids. Gene-edited lizards. Curiosity hunts Mars life. Video games that simulate millions of rays of light. Heartbeats sync with our movements

28 The mystery life inside us Our microbiome contains life forms we never knew existed 10 Secrets of Avebury Origin story of world’s largest stone circle Plus Black hole finally pictured (7). First GM reptiles (15). The four-day week (20). Colombia’s astounding biodiversity (37)

Ambitious space mission affirms faith in the future. Clean air is a basic right

18 IN BRIEF Cats know their names, they just ignore you. Dead planet around dead star. Four-legged whale. Microbes on the ISS

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Analysis 20 INSIGHT The complex case for a four-day week 22 COMMENT Tell people when genetic results change. The importance of hand-washing 23 ANALYSIS London leads on clearing up air pollution

Features 28 The mystery life inside us Our bodies hold microbes so strange they are rewriting biology 32 Going interstellar We are preparing to send spacecraft to a star system 4 light years away 37 Found worlds A race against time to save the newly discovered riches of Colombia

Culture 42 Green thinking An unsung eco hero and a “natural capitalist” plot unique paths for 21st-century life 43 All too much Making the right decision has become superhard PLUS: This week’s cultural picks 44 Our Planet David Attenborough stars in Netflix’s new flagship nature showw

Regulars 24 APERTURE Wooden wonders 52 LETTERS Petrol’s “gearing ratio” 55 QUICK CROSSWORD 56 FEEDBACK Papal hygiene 57 THE LAST WORD Toe uncurling

13 April 2019 | NewScientist | 3

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ASTRONOMERS have a trick to help them find the centre of the galaxy. The constellation Sagittarius forms a pattern in the shape of a teapot, and its spout points to an apparently unremarkable location called Sagittarius A*. This, 26,000 light years away, is the centre of the Milky Way, and the location of a supermassive black hole. No telescope on its own is powerful enough to glimpse it, but a collaboration of radio astronomy observatories around the world has now imaged the event horizon of the black hole. It is a remarkable achievement, but don’t hold your breath. The first ever photograph of a black hole is composed of just

two pixels (see page 7). It is a long way away, after all. Look instead to the Centaurus constellation. If you are in the southern hemisphere, or southern parts of the northern hemisphere, you can see Alpha Centauri, the third-brightest star in the sky. Only about 4.3 light years away, it is the closest star system to Earth. The system has one confirmed planet, called Proxima b. It is literally our interstellar next door neighbour. “Only” 4.3 light years. That is some 40 trillion kilometres, a distance it would take 80,000 years to traverse using our best current technology. But in 2016, a project was launched to build

A laser pushes a mini spacecraft’s light sail in this artist’s impression

mini spacecraft, accelerate them to 20 per cent of the speed of light, and reach our neighbours in 20 years. The scientific challenges are immense, but three years on from the announcement, progress is being made (see page 32). It may be optimistic to believe that we can develop the technology any time soon, but a project of such ambition and scope deserves our support. Few things are as inspirational and exciting as space travel, and if this ambitious and collaborative project does anything, it affirms a faith in the future. ■

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LET’s clear the air. Air pollution isn’t getting worse, at least not in most of the developed world. But our knowledge of its long-term harms is motoring forward. Air pollution is the new smoking, but is more difficult to tackle because it is insidious and implicates us all. Anyone who runs their children to school in the car, jumps on a plane to seek

the sun or even just shops in their lorry-supplied local supermarket is contributing to the problem. The good news is that air pollution’s effects are largely local, and with exceptions – notably aviation and shipping – can be tackled locally or nationally. Initiatives like London’s pioneering Ultra Low Emission Zone should be closely monitored

to see if they work (see page 23). But such mechanisms are crude, and risk penalising the poorest people. True change requires individuals, companies and governments all to adjust their behaviour and put clean air at the heart of what they do. Faced with incontrovertible evidence of risk, we have long adopted a zero-tolerance approach to unclean water. Just because air is invisible, doesn’t mean it should be any different. ■ 13 April 2019 | NewScientist | 5

THIS WEEK

Earth’s past and future ice

Bombs away on asteroid Ryugu

AROUND 95 per cent of glaciers in the Alps will be wiped out by the end of the century if the world continues pumping out carbon emissions at the current rate. That is the stark warning from research using a more realistic way of modelling how ice will react to rising temperatures due to climate change. “You get what you can’t really call glaciers any more, just some ice patches,” says Harry Zekollari at the Swiss Federal Institute of Technology in Zurich, who presented the work at the European Geosciences Union (EGU) conference in Vienna, Austria, this week. Today, there are about 3500 glaciers in the Alps, containing around 100 cubic kilometres of water. Some of those glaciers lie below the snow that thousands of people ski and snowboard across each year. The extent to which this ice will be lost hinges on how much carbon dioxide humanity emits in the coming years. Governments’ carbon-cutting plans under the Paris climate deal currently have the world on course

JAPAN’S Hayabusa 2 spacecraft has begun the space rock mining era with a bang by shooting a projectile packed with explosives at the rocky landscape of asteroid Ryugu. When the projectile got to about 3.5 metres above the surface, it exploded and sent up debris into the asteroid’s orbit, creating a fresh crater. Before the explosion occurred, Hayabusa 2 manoeuvred around to the other side of the rock to avoid being blasted. It will later collect a sample of dust to return to Earth. Ryugu is small – less than a kilometre across – and a relic from the formation of our solar system. Studying it could help us learn about the composition of early planets and determine how water and other materials crucial for life came to Earth. The blast aimed to probe beneath the surface and toss up particles that haven’t been altered by millennia of exposure to cosmic radiation.

But if tougher action limits the temperature rise to no more than 1.7°C, about 37 per cent of the ice will remain by 2100. “I think there is still hope. We see the emissions decide if there are some glaciers or not,” says Zekollari. But whatever action countries take on climate change, the Alps are already doomed to lose about half of their glacial ice by 2050. This is partly because glaciers

respond slowly to temperature changes, so some melting is already locked in by historical emissions. The other reason is that the different paths the world might take on emissions, as outlined by the UN climate science panel, stay relatively close to one another in the next two decades, but take very different trajectories later in the century. Details of a €13 million European

project, which hopes to find ice dating back 1.5 million years, will use the bubbles of CO2 and other gases trapped deep inside ice cores to provide a window into Earth’s past climate. So far, the oldest ice ever to have been drilled was a core that dates back 800,000 years, unearthed 15 years ago. That leaves a gap in our knowledge of a key period when Earth’s climate shifted, known as the mid-Pleistocene transition. In this period, the world changed from a rhythm of switching between warm and cold phases every 40,000 years, to a cycle every 100,000 years. There are competing explanations for why this happened, and the drilling project hopes to provide the evidence to explain it. “We need to understand why we have this change 900,000 years ago, and why we live in a 100,000-year [cycle] world. Without [doing] that, we cannot say we really understand our current climate systems,” says Barbara Stenni of Ca’ Foscari University of Venice, Italy.

to restrict the temperature rise to about 3°C by 2100, which would cause

project to drill several kilometres into Antarctic ice were also announced at

The ice will also provide crucial data to improve modelling of how

a 94.5 per cent decline in the mass of glaciers in the Alps.

the EGU conference this week. Researchers on the “Beyond EPICA”

our planet’s climate will evolve in the future, she adds.

“The Alps are already doomed to lose about half of their glacial ice by 2050”

UK considers tough internet rules A UK government white paper on online harms proposes strict rules that would require internet firms to take responsibility for the actions and safety of their users, as well as for the content that appears on their services.

PINO PACIFICO/REDA&CO/UIG VIA GETTY IMAGES

Companies that break these rules could see senior management held liable for the failings. The paper also proposes the creation of an independent regulator with the power to issue substantial fines and block access to websites. The proposed new laws would apply to any company that allows people to browse user-generated content or interact with other individuals online, including social media sites, messaging services and search engines. There will be a consultation before draft legislation is published, but critics are already warning that the rules could amount to censorship. 6 | NewScientist | 13 April 2019

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

First ever picture of a black hole Seeing a black hole could reveal new physics, says Chelsea Whyte

HOTAKA SHIOKAWA

WHAT is it like to stare directly into the dark heart of our galaxy? We are about to find out. The team at the Event Horizon Telescope (EHT) – a network of telescopes around the globe working together to image black holes – was set to release its first results as New Scientist went to press. Taking a picture of a black hole is hard because these objects don’t emit or reflect any light. So what will we see? “They’re trying to get an image of the black hole’s shadow,” says Avi Loeb at Harvard University. Black holes are surrounded by material that glows as it falls into their maw, and the black hole itself should obscure part of this matter. “It’s very different from the shadow cast by an opaque object because a black hole isn’t opaque, it’s absorbing light,” says Loeb. “As a result, we should see a dark inner region surrounded by a sliver of light that looks like a crescent moon.” That crescent shape is predicted by Albert Einstein’s theory of special relativity, which says that matter moving towards us will to be about 50 microarcseconds look brighter and anything wide. One microarcsecond is moving away will be dimmed. about the size of the full stop We may also see the effects of the at the end of this sentence – if immense gravity of a black hole, in viewed from the moon. the way it bends light that passes The resolution of the EHT is nearby – a characteristic known 20 microarcseconds at best, said as gravitational lensing, says Loeb. Falcke. That means we will only The EHT is targeting the two see fuzzy images of the two black biggest black holes in the sky holes – they won’t be anything from our point of view. The first like the artists’ renderings seen in is Sagittarius A*, the supermassive films like Interstellar, according black hole at the centre of the to Falcke, or the simulation above. Milky Way, the second is an even “It turns out that as big as larger black hole at the centre of we think a black hole would the Messier 87 galaxy, found in be, especially one we call the constellation Virgo. Despite this, the pictures will be “It turns out that as big as we think a black hole tiny. Heino Falcke, who works on would be, they’re actually the EHT, said on Twitter that the Sagittarius A* shadow is predicted very small on the sky”

A simulation of what a black hole might look like

supermassive, they’re actually very small on the sky,” says Dan Marrone, another astrophysicist who works on the EHT. “We need the telescope to be Earth sized.” That is why the EHT is made up of telescopes all over the world synchronised to collect data at the same time and in the same wavelengths. The data being released on 10 April will come from the 2017 operations, which included radio telescopes in the US, Chile, Spain, Mexico and at the South Pole. The images and data this concerted effort will produce could help us answer some of the

biggest questions in physics. For one thing, we will have the first image of the environment around a black hole, which can help us see if theories about the structure of these phenomena are correct. “Since the early 1970s, people have tried to model how gas would accrete onto a black hole and there are a lot of uncertainties,” says Loeb. Those include the magnetic fields around a black hole, which may play a role in creating jets like the ones emanating from M87. These streams of radiation and charged particles form out of the disc of material around the black hole and travel close to the speed of light, but we aren’t sure just how they come to be. We will also get a better idea of whether black holes behave as Einstein’s general theory of relativity suggests. “If I was a betting person, I would say the results won’t contradict general relativity,” says Samir Mathur at Ohio State University. The event horizon, or the point of no return, of a black hole is the front line of the battle between quantum mechanics and general relativity – our theories don’t agree on what really happens there. Mathur says the images aren’t likely to clear things up, because the light the EHT picked up isn’t coming from the event horizon, but from slightly further out. Light truly at the horizon would be swallowed up. Still, the images will be a great achievement, even if they aren’t really a surprise. “We have tested general relativity in these environments with gravitational waves, and the results pretty much agreed with what we expected,” says Loeb. “But in this case, we will be seeing it, and seeing is believing.” ■ 13 April 2019 | NewScientist | 7

NEWS & TECHNOLOGY

Doctors do surgery over 5G internet Yvaine Ye

A surgery is streamed in HD to doctors 200 kilometres away

CHINA NEWS SERVICE/VCG/GETTY

THE future of surgery is looking remote. Doctors in China have directed the heart surgery of a patient hundreds of kilometres away, using a 5G mobile internet connection. This follows on from a surgeon who recently used the same technology to remotely control a surgical robot for a procedure. The appeal of long-distance surgery is that leading specialists can help with operations even

when they aren’t able to get there. Until now, the lack of a fast enough reliable connection had been a stumbling block. On 3 April, cardiologist Huiming Guo directed surgery on a 41-year-old woman who had a hole in her heart because of a birth defect. Guo was in Guangdong General Hospital in Guangzhou, while the woman was almost 400 kilometres away in Gaozhou People’s Hospital. Before the procedure, Guo’s team worked out a surgical plan

using a 3D model of the defective heart, put together by an artificial intelligence using medical images such as CT and MRI scans. Guo and his team instructed the operating team on where to make cuts and stitches via a video conference link in 4K ultra-high definition. The remote team also monitored a live video from a camera probe inserted through the woman’s chest. “Advanced internet technology can save our doctors a lot of time because they don’t have to travel as much. They can use that time to save more lives,” said Zhiwei Zhang at Guangdong General Hospital in a press conference.

Promising chronic fatigue drug fails trials A MEDICINE that people hoped would treat chronic fatigue syndrome (CFS) has failed its first large placebo-controlled trial. The drug, called rituximab, is used to treat cancer and autoimmune diseases in which the immune system makes antibodies that turn against the body. The medicine works by killing the cells that make antibodies. 8 | NewScientist | 13 April 2019

A few people who had cancer and also happened to have CFS saw their symptoms of fatigue resolve after taking rituximab. Øystein Fluge of Haukeland University Hospital in Norway thought rogue antibodies could be involved in CFS, also known as myalgic encephalomyelitis (ME). These initial findings were borne out by some small studies. Fluge and his colleagues’ latest trial was larger, involving 151 people. Half had regular infusions of rituximab for a year, while the rest got placebo infusions. Their symptoms were measured over this time and for a further year, as the

drug can take several months to work. About 25 per cent of people in the treatment group saw their tiredness alleviate – but so did 35 per cent of people in the placebo group (Annals of Internal Medicine, doi.org/c4b5). Rituximab also caused a higher rate of side effects that required going to hospital, such as infections. Fluge says the first people who got better after taking rituximab may

“Some people are travelling to the US to get the drug even though it isn’t licensed for ME”

Others in China have also used the technique. Doctors wanting to learn about a procedure in the Second People’s Hospital in Guangdong used 5G to watch a stream from Yangshan Hospital in Guangdong, 200 kilometres away (pictured, below). And recently, neurosurgeon Zhipei Ling used a surgical robot to insert a deep-brain stimulation implant into someone with Parkinson’s disease. The surgeon was located in Hainan, while the patient was in Beijing, on the other side of the country. Ling works at both hospitals, but couldn’t fly to Beijing immediately when his patient needed surgery. The 5G network used by the hospitals is 10 times as fast as the 4G mobile internet currently in use, so it can provide more stable streaming. One major benefit of 5G is its reduction in signal delay, dropping from between 20 and 80 milliseconds with 4G to about 1 millisecond with 5G, says Rahim Tafazolli at the University of Surrey, UK. This reduction isn’t too important when there are human doctors on both ends of a connection, but it will make a huge difference during telesurgery, when a doctor operates remotely with a robot. This is what the future of healthcare will look like, says T. Sloane Guy at Weill Cornell Medicine in New York. ■

have done so because of the placebo effect, or because their condition naturally resolved. Alternatively, they could have been different in some way from other people with CFS. The results are a blow to the idea that antibodies cause CFS, says Fluge, “but it doesn’t exclude that other parts of the immune system are active in this disease”. Charles Shepherd of the UK’s ME Association says some people with the condition have travelled to the US to get rituximab treatment even though it isn’t licensed to be used in this way. Clare Wilson ■

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Snowflakes act as a blanket for the Arctic

The loss of the Arctic sea ice may threaten animals like polar bears, which rely on the ice to hunt, and elsewhere there are knock-on effects for weather and ecosystems. This century, the Arctic Ocean is expected to experience its first ice-free summer for 3 million years. The team also simulated changes in the ice until 2100, using a model that represents falling snow and assuming that we continue emitting lots of greenhouse gases. Existing models predict the first ice-free Arctic summer around 2072. However, the model suggested that the heating from snowflakes could bring it forward to 2052 (The Cryosphere, doi.org/c39q). This isn’t proof that Arctic sea ice will disappear faster than thought, says Li. It could be that other undiscovered processes will slow the retreat. “But we’ve found an important process that really seems to matter,” he says. Michael Marshall ■

CALLAO CAVE ARCHAEOLOGY PROJECT

FALLING snowflakes in the Arctic are trapping heat, which could be enough to speed up the melting of sea ice. As a result, Arctic seas could become ice-free up to 20 years earlier than expected. “It’s counter-intuitive because we think of snowflakes as being cold, but they’re slow-falling ice particles that act like blankets,” says Frank Li at the Jet Propulsion Laboratory in California. Sea ice in the Arctic tends to melt faster than forecast. So the team compared the few climate models that take snowflakes into account with the many that don’t to see if it could partly explain the difference. The group found that the extra heat trapped by snowflakes makes sea ice on average 30 centimetres thinner, and therefore more vulnerable to melting in summer. Climate change is melting the Arctic sea ice, which has been shrinking for decades. In January 2017, the area of the globe’s oceans covered by ice hit its lowest level on record.

Callao cave housed bones from a previously unknown ancestor

Another human species discovered in Asia IN CALLAO cave on the island Now we have confirmation. of Luzon in the Philippines, The team has found 12 more history may be repeating itself. fossils: seven teeth, two finger About 16 years ago, archaeologists bones, two toe bones and part of a working on the relatively nearby thigh bone. Some of the teeth have island of Flores discovered been dated as 50,000 years old. the remains of a previously This means the fossils are unknown ancient human species. roughly the same age as some Now a different team says of the “hobbit” human remains Luzon was once home to a found about 3000 kilometres mysterious human species “It is possible that small that it has named Homo groups of humans might luzonensis. The discovery have been accidentally raises an obvious question: did deposited on other islands” further human species evolve on other islands in the region? The first signs of ancient to the south on Flores in 2003. humans on Luzon came in 2007, But the Luzon fossils have distinct when a team co-led by Florent features and so belong to a Détroit at the French National different species, according to Museum of Natural History and Détroit and Mijares (Nature, Armand Salvador Mijares at the DOI: 10.1038/s41586-019-1067-9). University of the Philippines Détroit says it isn’t yet possible discovered a 67,000-year-old to know whether this species was human foot bone. small in stature like the Homo They tentatively assigned it floresiensis hobbits because there are so few fossils. But William to our species, but by 2016 there Jungers at Stony Brook University were rumours that Détroit and in New York says that the teeth Mijares had found more fossils and that they looked too primitive are extraordinarily small, “even in comparison to small-bodied to belong to Homo sapiens.

populations of modern humans from the Philippines”. Assuming H. luzonensis is accepted as valid, attention will turn to its ancestry. As with the hobbits on Flores, there are two leading possibilities: either it evolved from a relatively advanced species of human such as Homo erectus, which we know once lived in south-eastern Asia, or it descended directly from an ancient hominin similar to Lucy (Australopithecus afarensis). The second option is controversial because this species is so far known only from Africa. But it can’t be dismissed: the hand and foot bones of both H. luzonensis and H. floresiensis are notably similar to those of Australopithecus. The new discovery is likely to intensify the hunt for more extinct human species on nearby islands. Many researchers suspect that ancient humans lacked the ability to build boats and cross seas on a whim. They suggest it is more likely that early humans reached islands like Luzon and Flores by accident – perhaps after individuals living along coasts were washed out to sea during storms and deposited on a distant shore. Thomas Leppard at Florida State University favours this idea. It would fit the notion that the human remains on Luzon and Flores belong to different species. If early humans were routinely building boats and crossing between the islands of southeastern Asia, it is difficult to see how populations on relatively nearby islands could become genetically isolated long enough to evolve into new species. So, it is possible that small groups of humans might have been accidentally deposited on other islands in the region and – isolated from the rest of humanity – evolved into new species. Colin Barras ■ 13 April 2019 | NewScientist | 9

NEWS & TECHNOLOGY

Alison George

AVEBURY henge contains the world’s largest stone circle, but unlike its more famous neighbour Stonehenge, we know little about it. Now buried structures have been found at the monument that suggest the ancient complex began as a simple dwelling. The monument in Wiltshire, UK, is just 30 kilometres from Stonehenge. It comprises a 332-metre-wide stone circle, containing two further stone circles and avenues of paired standing stones. The entire site is surrounded by a circular ditch and embankment. But Avebury’s origins have been uncertain, as it hasn’t been investigated to the same extent as Stonehenge. The last major excavation took place in the 1930s, and couldn’t determine whether Avebury was constructed gradually over time, or as one large entity. To investigate, Mark Gillings at the University of Leicester, UK, and his colleagues used groundpenetrating radar to look for buried structures, as well as re-examining records of earlier investigations. The team focused

Face-mapping tool could spot rare conditions CHILDREN with rare conditions could be diagnosed quicker thanks to 3D facial analysis software. Richard Palmer at Curtin University in Western Australia and his colleagues have developed a tool that can spot subtle, but significant, differences in facial geometry. Around one in three rare conditions show up in facial features. For example, 10 | NewScientist | 13 April 2019

on the southern inner stone circle, which is 100 metres wide. The radar survey found a square of standing stones buried in the middle of the circle, with sides 30 metres long. “To find a square megalithic structure is very unusual,” says team member Joshua Pollard of the University of Southampton, UK. The square was built around another structure, which appears to be the remains of a Neolithic house, in the geometric centre of the southern inner stone circle. This leads the team to believe that the monument started out as a house in the early Neolithic era. Flint tools at the site and the age of similar dwellings elsewhere suggest this was around 3700 BC. Some time later, the site may have been turned into a monument with the erection of the stone square that was later enclosed by stone circles and the embankment. Pottery found in the stone holes suggests this may have happened around 3000 BC (Antiquity, DOI: 10.15184/ aqy.2019.37). “It’s a monument that developed in a series of stages,” says Pollard. But why did prehistoric people

foetal alcohol spectrum disorders, a group of conditions caused by alcohol exposure in the uterus, often lead to a thin upper lip, a smoother area between the top lip and bottom of the nose and a shorter distance between the eyes. The team’s tool, called Cliniface, scans a person’s face to create a 3D image and measures the distances between their features, comparing this with the average for their age, sex and ethnicity. The way a face changes as someone ages depends on their ethnicity and sex. If the measurements

CULTURA/CRAIG EASTON/GETTY

A neolithic shrine to a humble home?

We know less about Avebury (above) than nearby Stonehenge

go to such lengths to create a monument around what was once a modest dwelling? The team thinks the site of the house may have taken on special value to the descendants of those who built it, who then commemorated the site with stone monuments. Think of Elvis Presley’s home, Graceland, says Pollard. “It was once just a house, now it’s a shrine.” For now, though, this idea is unproven. “It’s an interesting

taken by Cliniface are far from the average for someone in their demographic, it will flag the deviations and label the symptom. The clinician then uses this information to make a diagnosis. The tool uses databases with predominantly European Caucasian measurements, but other databases can be added. Currently, diagnosing some conditions requires doctors to

“Currently, diagnosing some conditions requires doctors to measure the face with calipers”

piece of work,” says Timothy Darvill of Bournemouth University, UK. But without firm dates for the construction of the Avebury megaliths, “it’s not a clincher”, he says. To address this, the team plans to carry out further investigations at Avebury. “We hope that, in the next five to six years, we will get a better understanding of precise chronology,” says Pollard. The team also wants to investigate Avebury’s northern inner stone circle to see whether that, too, might have been built on the site of an earlier house. ■

measure the face with calipers and look at a set of reference images, which is a difficult process. In contrast, any picture taken with a suitable camera can be run through the software, says Palmer. The tool is still a long way from replacing human expertise, says Natasha Brown at the Victorian Clinical Genetic Service in Australia. “No one tool is perfect, and so what we need to do is synthesise the information with our clinical experience and with the experience of our colleagues,” she says. Ruby Prosser Scully ■

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NEWS & TECHNOLOGY Two-millionyear-old toothache

rim around a hole in the upper jaw, a telltale sign. “That’s where the bone started to remodel where the abscess had been,” he says. “I knew straight away that that one had formed during life.” The abscess appears to have been caused by bacteria attacking the individual’s teeth. These were probably worn down from eating hard, uncooked food that – because of a lack of culinary hygiene – may also have carried grit into the mouth (bioRxiv, doi.org/gfxr24). It is unlikely that the early human would simply have tried to ignore the abscess pain, says Karen Hardy at ICREA, the Catalan Institution for Research and Advanced Studies in Spain. Ancient cultures are known to have used plants such as marjoram and ginger to soothe toothache. SK 847 may have used similar remedies, although there is no specific evidence to suggest this. Chris Baraniuk ■ 12 | NewScientist | 13 April 2019

CAIAIMAGE/CHRIS RYAN/GETTY

IT MUST have been agony. Two million years ago, an early human probably tossed and turned, unable to sleep as the front of their mouth throbbed incessantly. Their teeth were worn down so much that root canals had been exposed. And above the upper incisors lay at least one dental abscess – a mass of pus growing inside the jaw, caused by bacterial infection. Of course, there were no dentists to relieve the pain. The individual may even have died from blood poisoning caused by the abscess. This sorry situation was revealed by new analysis of a hominin specimen, SK 847, which was discovered in South Africa in 1969. Researchers recently inspected around 20 early human jaw fossils from southern Africa, of which SK 847 was one. Its specific species is disputed. However, the find may be the earliest dental abscess in the genus Homo ever found, says Ian Towle at Liverpool John Moores University in the UK. The specimen has a small

Humans are good at maths – artificial intelligences less so

DeepMind’s AI fails maths exam Adam Vaughan

much bigger numbers (arxiv.org/ abs/1904.01557). Other oddities included the ability to correctly answer 68 to the question “calculate 17×4.”, but when the full stop was removed, the answer came out at 69. The DeepMind researchers say they don’t have a good explanation for this behaviour. “At the moment, learning systems like neural networks are quite bad

ARTIFICIAL intelligence firm DeepMind has tackled games like Go and Starcraft, but now it is turning its attention to more sober affairs: how to solve school-level maths problems. Researchers at the company tasked an AI with teaching itself to solve arithmetic, algebra and probability problems, among others. It didn’t do a very good job. “It could successfully add When the neural network was up 1+1+1+1+1+1 to make 6, tested on a mathematics exam but failed to get 7 when taken by 16-year-olds in the UK, an extra 1 was added” it got just 14 out of 40 questions correct, or the equivalent of an E grade. at doing ‘algebraic reasoning’,” There were also strange quirks says David Saxton, one of the in the AI’s ability. For example, team behind the work. it could successfully add up Despite this, it is still worth 1+1+1+1+1+1 to make 6, but trying to teach a machine to solve failed to get 7 when an extra 1 maths problems, says Marcus du was added. Sautoy, a mathematician at the However, it gave the correct University of Oxford. answer for longer sequences and “There are already algorithms

out there to do these problems much faster, much better than machine-learning algorithms, but that’s not the point,” says du Sautoy. “They are setting themselves a different target. We want one to start from nothing, by being told whether it got that one wrong, that one right, whether it can build up how to do this itself. Which is fascinating.” An AI capable of solving advanced mathematics problems could put him out of a job, says du Sautoy. “That’s my fear. It may not take too much for an AI to get maturity in this world, whereas a maturity in the musical or visual or language world might be much harder for it. So I do think my subject is vulnerable.” However, he thinks that machine learning’s general struggle to remain coherent over a long form – such as a novel, rather than a poem – will keep mathematicians safe for now. Creating mathematical proofs, rather than solving maths problems for 16-year-olds, will be difficult for machines, he says. Saxton says training a neural network on maths problems could help provide AI with reasoning skills for other applications. “Humans are good at maths, but they are using general reasoning skills that current artificial learning systems don’t possess,” he says. “If we can develop models that are good at solving these problems, then these models would likely be using general skills that would be good at solving other hard problems in AI as well.” Saxton hopes the work could make a small contribution towards more general maths AIs that could tackle things such as proving theorems. The DeepMind team has published its data set of maths questions, and it is encouraging people to train their own AI. ■

Where did we come from? How did it all begin?

And where does belly-button fluff come from? Find the answers in our latest book. On sale now. Introduction by Professor Stephen Hawking

NEWS & TECHNOLOGY

The world’s first GM reptiles Michael Le Page

A brown anole lizard and one of the gene-edited albino variants

DOUG MENKE

THE CRISPR genome-editing tool has been used to make the world’s first genetically modified reptiles: four albino lizards. Our ability to tweak the genomes of animals like mice and zebrafish has been hugely useful for medical research. But some conditions are hard to study in existing lab animals. For instance, people with albinism often have vision problems because the genetic variants responsible affect the

development of the fovea, the part of the retina that provides the most detailed picture of the world. Mice and zebrafish don’t have foveae – but lizards do. Until now, however, there has been no way to deliberately change the genome of any reptile because the techniques used in other animals don’t work as well for some egg-laying animals. Douglas Menke at the University of Georgia and his team anaesthetised female brown anole lizards (Anolis sagrei) and injected the CRISPR genome-

editing machinery directly into eggs developing in their ovaries. The trick is to inject each egg at the right stage of development. If done too soon, it doesn’t work well; too late and there is a high risk of damaging important structures inside the egg. The team used the technique to create albino lizards because their lack of pigmentation makes it easy to tell when the gene editing has worked. In addition, team member Jim Lauderdale hopes to use gene-edited lizards to study how albinism affects the fovea. In the team’s initial study, nine out of 146 eggs that were injected were successfully gene edited (bioRxiv, doi.org/10.1101/591446).

Curiosity rover enters possible Mars life zone NASA’s Curiosity rover is starting to explore what may be the best region on Mars for life to flourish now or in the past, according to an analysis of the kind of Martian clays it will study. Patricia Craig at the Planetary Science Institute in Arizona and her colleagues placed bacteria in test tubes with clay minerals of the type found on the Martian surface. They

then left the microbes for 195 days to see if they would survive. The results were encouraging, says Craig: “We didn’t kill them!” In fact, the microbes continued to produce methane when fed on only Mars-like clays, indicating that they were drawing nutrients from the material. Methane gas has been repeatedly detected in the Martian atmosphere, and some researchers have suggested that microbes like these could be producing it. But the changes in the test tubes were difficult to spot, with both X-ray and infrared examinations showing

no differences in the clay. Only with a scanning electron microscope (SEM), which shines a beam of electrons on a sample and creates a picture from its reflection, could any changes be detected. The SEM showed differences in the spacing of the clay mineral layers, as well as imaging what seemed to be a living microbe. Curiosity has just entered a region of Mars that is likely to have more

“Even after 195 days, the microbes continued to produce methane when fed on only Mars-like clays”

The team says it has managed to improve this efficiency rate. “This is really a big achievement,” says Maria Antonietta Tosches of the Max Planck Institute for Brain Research in Germany, who has tried to modify another species of lizard. “I know how hard it is.” Anole lizards are the subject of many evolution studies, as they rapidly adapt to new niches and have diversified into hundreds of species. Menke hopes to use gene editing to learn more about how they have done this. The team thinks its technique will succeed in any kind of reptile, from lizards and turtles to snakes and crocodiles. “I would certainly think that the same approach would work,” says Menke. He believes it might also be possible to adapt the method to birds, which are – evolutionarily speaking – a type of reptile. Many teams have created genetically modified birds, including CRISPR-edited ones, but the techniques used are complex and difficult. “The process is laborious,” says Tosches. She isn’t sure the new method will work in birds. “We will have to wait and see,” she says. It may also be difficult to get the timing right for reptile and bird species that only lay eggs once a year. The brown anole lays one egg a week, meaning it always has eggs developing in its ovaries. ■

clays than the rest of the surface, so these results may mean we are rolling into the best place to spot life there. Unfortunately, SEMs are too large to fit on a rover, so even if Curiosity sees signs of life it probably won’t be able to tell what they are. The methane in Mars’s atmosphere could be produced by microbes or by geological processes like outgassing from ice deposits, and without an SEM it will be nearly impossible to tell its true origin, says Craig. She presented the results of the experiment at the Lunar and Planetary Science Conference in Texas. Leah Crane ■ 13 April 2019 | NewScientist | 15

NEWS & TECHNOLOGY

NVIDIA

Sync your heart with others to work together

Light rays create stunning visuals Andrew Rosenblum

A 1000-frame section of raytraced footage of post-apocalyptic Las Vegas in Blade Runner 2049, lasting less than a minute, for example, took 13 hours of processing on a powerful server farm. The cost of ray tracing in films is about $1 million per produced minute, says Kim Libreri, now at Epic Games, who used the technique when working on the visuals of all three Matrix films. For video games, ray tracing simply wasn’t plausible because home computers weren’t

“OH, THAT looks gorgeous,” drawls an onlooker in a Texan accent, as I guide my fighter through a gloomy, broken-down shack in a video game called Metro Exodus. I’m struggling in hand-to-hand combat with a zombie, so Dmitry Zhdan, who worked on the game, grabs the controls and clobbers my foe with a rifle butt. Zhdan is keen for me to stay alive in this ramshackle structure, so I can take in the bright desert sunlight splintering through the “The chips calculate up to windows. It shows off the game’s 83 million interactions impressively realistic graphics, between light and visual made possible by a technique elements in a single frame” called real-time ray tracing. Metro Exodus started offering powerful enough to create the the feature last month, which high-quality visuals in real time uses a new generation of as the player moves around and computer chips that can perform interacts with the world. the massive calculations needed. Now, however, US firm Nvidia Ray tracing simulates how makes chips that specialise in individual rays of light enter ray tracing, and game developers a scene and reflect off objects, use tricks to save processing resulting in incredibly lifelike power, such as rendering scenes visuals. Until now, it was reserved with a hybrid of ray tracing and for films with big budgets older, faster techniques. and even bigger computers. 16 | NewScientist | 13 April 2019

Ray tracing creates hyperrealistic scenes in video games

Nvidia’s specialist chips can produce between 23 and 73 frames of ray-traced Metro Exodus scenes every second. When rendering a scene in 4K on the highest “ultra” setting, Metro Exodus casts one ray for each of the roughly 8.3 million pixels on the screen. Zhdan estimates that the chips calculate up to 83 million interactions between light and visual elements in a single frame. Other video games such as Battlefield V and Shadow of the Tomb Raider have also explored real-time ray tracing. And recently the blocky, worldbuilding game Minecraft was made far more realistic using a similar technique. However, despite the cost coming down, many people won’t want to pay $400 to $1500 for a ray-tracing chip for their home computer. And even with souped-up processors, ray tracing can impose a performance penalty, says Zhdan, meaning fewer frames are rendered per second. “It’s still early days,” says Libreri. Ray tracing is best for story-oriented or action games where the interplay of light and shadow are particularly important. But he thinks it will eventually become the norm. ■

YOUR heartbeat might help you cooperate. When we make a movement, even a small one, it is most likely to end exactly in the middle of a heartbeat – and this synchronisation happens when we watch someone else do the same thing. This could be how our bodies help us align our actions with those of other people. “We don’t yet know if the heartbeat is guiding the action or responding to it,” says Eleanor Palser at the University of California, San Francisco. She and her colleagues examined how heartbeats sync with actions using electrocardiograms, which measure the electrical activity of the heart. Previous work has shown that heartbeats sync with walking speed, but this test measured heart activity while using fine motor skills. Palser and her colleagues asked 26 people to sit in pairs across from each other at a table equipped with four touch-sensitive pads and a marble. The pairs took turns moving the marble from pad to pad after memorising a sequence on a screen. The team found that the end of each movement was more likely to occur between heartbeats than during a heartbeat. What’s more, the heartbeats of people who were watching their partner move the marble lined up with the action in the same way (bioRxiv, doi.org/gfxcq8). Palser says the findings suggest that our bodies help us sync with others to perform a task. Some hypotheses suggest the synchronisation may be driven by a feedback loop between the heart and the brain, which involves cells called baroreceptors that tell the brain when the heart muscle contracts. It may also have to do with the nature of the task. Konrad Kording at the University of Pennsylvania says that biathletes, who ski and then fire a rifle at a target, take time to slow their heartrate so they can take a steady shot. A similar thing may be going on here, he says. Chelsea Whyte ■

ALL CANADA PHOTOS/ALAMY STOCK PHOTO

IN BRIEF Body illusion shines new light on autism

Arctic island is collapsing as a result of climate change SATELLITE images are revealing how the landscape

movement over years, is that they are in northern areas where the permafrost wasn’t thought to be at risk. Fortunately, only parts of the Arctic where the permafrost contains a lot of ice are vulnerable to this kind of land movement. Despite their name, it was

of part of the frozen north of Canada is being reshaped by land slumps triggered by global warming.

thought that these thaw slumps were triggered by processes such as erosion by waves or rivers.

The number of slumps on Banks Island has risen from 63 in 1984 to more than 4000 in 2013. “It is clear that

But when Lewkowicz and his team used satellite images to study Banks Island, they found that almost

something really dramatic is happening,” says Antoni Lewkowicz of the University of Ottawa in Canada.

all the slumps first formed when particularly warm summers cause deeper thawing of the land surface

Around the southern edges of the Arctic, the melting of permafrost is already causing buildings to tilt and

than usual (Nature Communications, doi.org/c375). Even if we limit warming to 2°C, computer models

roads to buckle. What is worrying about the land slumps, which usually start as landslides followed by slower land

suggest that by 2075, more than 10,000 new slumps will be forming on Banks Island each decade.

Zombie planet seen orbiting dead star A PIECE of a planet that survived the explosion of its star has been spotted orbiting the stellar corpse. This gives us a glimpse of what our solar system may look like when the sun dies. Christopher Manser at the University of Warwick, UK, and his colleagues noticed something unusual when observing a white dwarf, the remnant of a star that has consumed all of its fuel. 18 | NewScientist | 13 April 2019

The team looked at a dusty ring around the star, thought to be from planets destroyed when the dying star exploded. They saw a fluctuation in the wavelength of the light emitted by the dust. This signal repeated every 2 hours, suggesting that something was rapidly orbiting the white dwarf, which is 400 light years away from us. Manser says it could be a bit

of a planet about 800 kilometres across, orbiting close to the white dwarf. It must be very dense, perhaps made of iron or other heavy metals, to prevent it being torn apart by the star’s gravity (Science, doi.org/c378). Most rocky planets in our galaxy are composed of the same elements, says Ben Zuckerman at the University of California, Los Angeles. He suggests that planets in our solar system could share the same fate.

PEOPLE with autism don’t seem to experience a bodily virtual-reality illusion that other people fall for. Some view autism as a different way of seeing the world. So Jane Aspell at Anglia Ruskin University, UK, and her team wondered if autistic people perceive a particular illusion differently. It involves using virtual reality goggles that let you view your own body as if you are looking at someone else. You then see this avatar being stroked on its back, at the same time as your own back is stroked. This usually makes people feel that they are starting to embody the avatar, and their sense of location shifts towards it. Aspell’s team recreated the illusion for 51 people, about half with autism. Those with autism weren’t susceptible (Autism, doi.org/c372). This suggests that, in autism, “the way the brain is generating a sense of self is somehow different”, says Aspell.

Seeing the trees through the wood TRANSPARENT wood could one day replace glass in windows. A process for turning it see-through also gives it heat-retaining powers. Céline Montanari at the KTH Royal Institute of Technology in Sweden and her colleagues built on previous work, which created partially transparent wood by removing a structural component called lignin from wood. To improve transparency, the team soaked de-lignified birch wood in PEG (polyethylene glycol). This version still isn’t perfectly clear – when the PEG is solid, the material has a white haze similar to frosted glass. But Montanari is confident these early challenges can be overcome. The work was presented at a meeting of the American Chemical Society.

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CAT owners are familiar with the hopeless feeling of calling the name of their beloved pet, only to be ignored. Or, even worse, abandoned with a dismissive flick of the tail. An analysis has found that cats really do know their names, it seems they just don’t care when you use them. Atsuko Saito at Sophia University in Japan and her colleagues wanted to see if cats could tell their name from other similar-sounding words. The team visited homes and cat cafes, where diners mingle with pets, to analyse the way the animals move their ears, heads, tails and feet in response to the sound of various words. They played recordings of the pet owner saying four words with the same length and accent as the cat’s name. This was followed by a recording of the actual name. Many of the cats were likely to become accustomed to the words, so if they did recognise their name, Saito and her colleagues believed they would see a different reaction when it was spoken. In the test, 11 of 16 cats showed a drop in activity between the first and fourth word being spoken, suggesting they were getting used to the recordings. Of those 11, nine reacted again when their name was played (Scientific Reports, doi.org/c377). As for why cats don’t always come when called, Saito says

ADAM GOFF

they are just ignoring you.

NASA finds microscopic life thriving in orbit ASTRONAUTS on the International Space Station are far from alone. It is teeming with non-human life. NASA has created a catalogue of all the microbes inside the base to help it develop safety precautions for future long-term space travel, such as sending people to Mars. Microbes thrive on the ISS because of factors such as the confined living space. The lack of many naturally occurring rivals also creates a niche for certain strains to successfully occupy. To understand which bacteria and fungi are on the ISS, Kasthuri

Venkateswaran at NASA’s Jet Propulsion Laboratory in California and his colleagues asked astronauts to take samples from eight locations on the space station. Some were from high-traffic places, such as the bathroom and dining table, while others were from less-used areas. The first two samples in each location were taken a few months apart in 2015, and a third a year later. Genetic sequencing was used to identify organisms that can’t be grown in a dish, which the researchers estimate make up

between 40 and 60 per cent of all microbes on the ISS. They found hundreds of thousands of strains (Microbiome, doi.org/c397). “The majority of bugs we see on the ISS are benign, as in our home or office,” says Venkateswaran. It is likely they have been there since the first crew arrived, he says. Opportunistic pathogens were also found, such as Staphylococcus aureus and Enterobacter. These are often harmless unless people have compromised immune systems. The team don’t yet know how virulent these strains are. ALBERTO GENNARI

Kitty knows name but shows disdain

No hiding place for polluting farmyards ARTIFICIAL intelligence is helping locate livestock farms that may be illegally contaminating waterways. Concentrated animal feeding operations (CAFOs) – intensive farms with as many as 125,000 chickens – hold about 40 per cent of livestock in the US. Waste from these often gets into rivers and streams untreated, and the Environmental Protection Agency estimates that nearly 60 per cent of CAFOs lack the necessary permit for doing this. Finding potential offenders usually involves manually inspecting satellite images. To do this more efficiently, Daniel Ho and Cassandra Handan-Nader at Stanford University in California trained an AI to identify hallmarks of CAFOs, such as multiple rectangular barns, in images. Scanning satellite imagery of North Carolina, the algorithm found 15 per cent more poultry CAFOs than were known (Nature Sustainability, DOI: 10.1038/ s41893-019-0246-x). Some may have been built since the previous manual count, but it is likely that those checks missed farms, says Ho. He believes algorithms will eventually be able to detect pollution in waterways too.

Walking whale conquered America A FOSSIL of a whale from 43 million years ago that was able to walk on land on four legs has been found in Peru. It is the first amphibious whale found in the southern hemisphere, and suggests that whales managed to swim across the South Atlantic early in their evolution. The 3-metre-long animal looked a bit like an otter or beaver, with four legs and a large tail for swimming, according to an analysis by Olivier Lambert at the Royal Belgian Institute of Natural Sciences and his team (Current Biology, doi.org/c376). Whales started evolving in South

Asia about 50 million years ago, from a dog-like creature related to deer and hippos. As they became more aquatic, these early whales began spreading along coasts. Fossils of semi-aquatic whales have recently been found in West Africa. The latest discovery suggests that these early whales managed to swim from there to South America at least 43 million years ago. At the time, West Africa was 1200 kilometres from South America. This means the whales were probably capable of surviving without fresh water and could sleep at sea.

13 April 2019 | NewScientist | 19

INSIGHT FOUR-DAY WEEK

Time for some more time off Cutting down the hours we work sounds appealing, but would we really benefit and is it at all feasible? Michael Le Page investigates A GROWING movement wants to radically change how we live. The people behind it say it will make us healthier, happier and more productive. It will put a massive dent in carbon dioxide emissions and ease the pressure on nature. And it will make countries richer and more equal. But are we really ready for a four-day week? In the UK, at least, the idea is gaining ground. Some trade unions have come out in support, the Labour party and the Scottish National party are discussing the idea and a few small firms are already trying it. The Wellcome

A 1% decrease in working hours could lead to a 0.8% drop in carbon emissions Trust, a science charity with 800 staff, is also considering it. The suggestion is that society moves away from typical working patterns of 40 hours over five days, a convention that has its roots in the 19th-century labour movement. Instead, campaigners want us to work no more than 32 hours over four days – but still get paid for all five. “We are making the case for a reduction in working time without a reduction in pay,” says Aidan Harper of the New Economics Foundation, a UK think tank that backs the 4 Day Week Campaign. A January report by the campaign lays out a huge body of evidence showing that working long hours is bad for physical and mental health. But many of those 20 | NewScientist | 13 April 2019

studies looked at people working 50 to 60 hours a week rather than comparing five working days to four. And there is plenty of evidence that being unemployed or having little work is bad as well. So how much work is too much? Huong Dinh at the Australian National University and her colleagues used survey data from 8000 individuals to try to figure out how many hours people can work before their mental health starts to decline (see graph, right). On average, the threshold is 39 hours – almost the same as a 40-hour week, although much less than the legal limit of 48 hours in many countries. But the situation is very different for women with unpaid care commitments: their mental health begins to decline after just 31 hours of paid work. So the current system puts women at a big disadvantage. Which leads to another reason for introducing a four-day week: to make society more equal. The idea is that it will help women compete on a more equal footing and increase employment as work is shared among more people. There is still a massive gulf between the sexes. The gender pay gap is around 20 per cent in the UK, and women still do most of the childcare, housework and caring for relatives. The argument is that more women could work full-time and more men could take on care responsibilities if everyone did a four-day week, with the entire economy profiting. There is some evidence that women do benefit when working hours are reduced: they report higher job satisfaction and are less likely to be forced to take part-time jobs.

The number of hours people can work before their mental health declines depends on personal circumstances with unpaid care commitments Men 43.5 42 Women 38 31 SOURCE: doi.org/f9xgv6

Average 39

“A culture in which different uses of time are expected from women and men has been the single most important barrier to equal opportunity,” says Anna Coote, also of the New Economics Foundation. This hasn’t just been bad for women, she says. “Men have been cut off from their children and family life.” A four-day week would make a tremendous difference, but our working culture needs to change, too, says Coote. “There’s no magic bullet here. It’s not going to happen overnight.”

Less work, more jobs Would a shorter week create more well-paid jobs, reducing the gap between the haves and have-nots? Here economists point to what they call the lump of labour fallacy: there isn’t a fixed amount of work to be done, so cutting working hours doesn’t create an equivalent number of jobs. Other researchers say this is true only in the narrow mathematical sense that working one day less won’t create exactly a fifth more jobs. There is plenty of evidence that if done in the right way, cutting hours can boost

employment. In 1933, for instance, president Franklin D. Roosevelt asked employers in the US to reduce the working week from the 40 to 50 hours typical at that time to 35 hours, while increasing wages. The voluntary scheme created 1.3 million jobs. There is a more surprising reason for moving to a four-day week: it could limit further global warming. Numerous studies have shown a strong link between greenhouse emissions and working hours. For instance, Jörgen Larsson and Jonas Nässén at Chalmers University of Technology in Sweden found that a 1 per cent decrease in working hours leads to a 0.8 per cent drop in emissions. This has led to claims that introducing a four-day week could cut emissions by 16 per cent. Unfortunately, the main reason is that people who earn less consume less. So while cutting out one day’s commute would help, emissions wouldn’t fall drastically if people keep the same salary. “You cannot have them both at the same time,” says Larsson. For some, a move away from rampant consumerism and a focus on happiness rather than economic growth is exactly what is needed. But according to the UK’s Office for National Statistics, while a third of the nation’s 30 million workers want to work fewer hours, only 3.3 million would accept lower pay. On the flip side, why should companies and countries pay people the same for doing less work? Some believe they don’t have to. According to a trial at a financial services company called Perpetual Guardian in New Zealand, not only can people

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There is indeed plenty of evidence that shifting to a four-day week could have a range of benefits, but also that not all of those benefits can be maximised at the same time. For instance, if people do five days’ work in four, there will be no increase in jobs, so unemployment will remain unchanged. Forcing people to work more intensely to keep the same pay could increase stress, but earning less could also

THOMAS NORTHCUT/GETTY

A third of the UK’s 30 million workers want to work fewer hours

do their job in four days instead of five, they can also do it better. The firm’s founder, Andrew Barnes, acknowledges that, say, healthcare services would have to employ more doctors or nurses if they switched to a four-day week, but he says staff would treat patients more efficiently and with better results. “Would you rather be operated on by the doctor who is fresh or the one who has been working for

More than 60% of people in the UK back a four-day week

10 hours?” he says. “The four-day week is a discussion about productive outcomes as much as one about work-life balance.” On a larger scale, campaigners say countries where people work fewer hours tend to have stronger economies. Within Europe, working hours are lowest in countries with thriving economies such as Germany, the Netherlands and Norway, and highest in struggling Greece. Productivity in the UK is 25 per cent lower than in Germany, but 10 per cent higher than in Japan, which has a culture of working extreme hours. However, Jon Boys at the

A four-day week would give us much more leisure time

Chartered Institute of Personnel and Development in the UK isn’t convinced. There are lots of anecdotal claims about increased productivity at companies, he says, but no large, rigorous studies to back this up. Nor does Boys think you can draw any firm conclusions by comparing countries because there are so many other factors involved. That said, he is still in favour of a four-day week, although he thinks productivity has to improve first. So where does all this leave us?

be stressful for those on low pay. “There seems to be no one-sizefits-all approach to working time reduction that would attain all objectives and perform well in all areas,” cautions a report for the European Trade Union Institute. Nevertheless, there is broad support for the idea from many sectors. “Working time on its own is not the one answer to climate change, but it can improve all of these other things too: the environment, unemployment, health,” says Jared Fitzgerald of Boston College in Massachusetts, who, with his colleagues, has found a strong link between working hours and carbon emissions in the US. “As an overall sustainability issue, it can be pretty powerful.” Fitzgerald thinks there is no prospect of the US introducing a four-day week. The need for people to work a certain number of hours to get health insurance makes it a non-starter, he says. However, a poll this January discovered that more than 60 per cent of people in the UK, Sweden and Finland support the idea. Harper thinks it could happen in just a few years. “Surely the aim should be to create the conditions in which we can live good lives,” he says. ■ 13 April 2019 | NewScientist | 21

COMMENT

The genetic road ahead Our understanding of genetic test results can change. When it does, we must tell people, say Rachel Horton and Anneke Lucassen

JOSIE FORD

IMAGINE a doctor saying that you have a version of a gene called BRCA1 that means you have a high chance of developing breast and ovarian cancer. You might make choices about screening or surgery. You might tell your family so they can get tested. But now imagine that new evidence suggests that your risk of cancer is far lower than was thought when you had your test a few years ago. Would you want to know? People expect genetic results to be certain, but sometimes this isn’t the case. As it gets easier to analyse DNA, we are gathering more data about the wide range of genetic variation, and finding that the context in which genetic variants are found can determine how serious they are. Our understanding can change even for well-known genes like BRCA1: some variants of it aren’t as closely linked to cancer as we

Let’s clean up our act Telling us to stop washing our hands is dangerous, says Sally Bloomfield “TWO-second rule!” shout our children as they snatch food off the floor. It is often stated that we are too clean, that we need to get dirtier for the sake of our health. You will have heard it referred to as the hygiene hypothesis. This concept proposed that rising levels of allergies might be linked to lack of exposure to childhood 22 | NewScientist | 13 April 2019

aren’t those that cause infections, but friendly ones that we acquire from people, animals and our environment. These stop our bodies from reacting to harmless stimuli like pollen or foods. Without them, we are at higher risk of developing allergies and immune disorders. Lifestyle changes including an increase in caesarean sections, smaller families and less time outdoors are now seen as the likely causes of reduced exposure to

infections, because of higher standards of hygiene. This is now known to be incorrect. Yes, contact with microbes is vital to our health, but the devil is in the detail. It is now thought “Hygiene in our daily lives that during human evolution, microbes evolved an essential role is crucial in preventing in regulating our immune system. the spread of infectious diseases” However, the microbes involved

thought a few years ago. As clinicians researching ethical issues, we are interested in what should happen in situations like this. Should people be re-contacted if interpretation of their genetic results changes? How significant does the change need to be? People’s health choices shouldn’t be based on inaccurate information. But equally, contacting a person might be stressful for them, especially if they have already made big decisions. The European Society of Human Genetics published guidelines on this matter in everyday healthcare last year. And last week, the American Society of Human Genetics produced guidance for researchers running genetic studies. This says that researchers who have previously communicated genetic results to participants should try to update

friendly microbes, together with antibiotic use and altered diet. But there is little evidence that personal or household cleanliness – as suggested by the hygiene hypothesis – is involved. The childhood infections that hygiene measures combat appeared too late in our evolution to have evolved an essential role in our immune system. Despite this, the International Scientific Forum on Home Hygiene found that the majority of news articles published over the past 20 years on the subject cite hygiene as a cause of reduced exposure to friendly microbes. Continuing to use this hygiene

For more opinion articles, visit newscientist.com/opinion

Rachel Horton and Anneke Lucassen are clinical geneticists based at the University of Southampton, UK

hypothesis misnomer is confusing for the public, and undefined messages in the media suggesting we stop washing our hands are unacceptable. We don’t know which lifestyle changes will reconnect us best with friendly microbes. But we do know that hygiene in our lives and homes prevents the spread of infectious diseases. Targeted hygiene will help us cut infections and the use of antibiotics to fight them. And that will be a huge boost to public health. ■ Sally Bloomfield is an honorary professor at the London School of Hygiene and Tropical Medicine

ANALYSIS Air pollution

BLOOMBERG/GETTY IMAGES

them if the interpretation changes – especially if this might affect future medical care. These guidelines are welcome, but they are just a start. In practice, doctors working in routine medical care are still grappling with how, and when, situations like this should be handled. Currently, each case is considered individually, which puts a great deal of responsibility on doctors. One improvement would be to tell people at the outset that the meaning of their genetic results could be overturned, so that being contacted again isn’t a surprise. Responsibility to re-contact people who have taken tests should extend to private genetic testing companies like 23andMe too, although here things are more complicated. These firms typically look at thousands of genetic variants and use them to place a person in a risk category. How far does a person’s risk have to shift before the company has to pick up the phone? The jury is still out on that, but for the moment, companies could at least serve up their results with a much bigger pinch of salt. ■

Can London show the way to clean dirty air? Adam Vaughan

struggle with the urban pollution,” says Frank Kelly at King’s College London. Authorities say the zone is about improving public health, not revenue, and that set-up costs mean they will probably lose money in the first five years. So what will the impact be? Taken together with steps to clean up buses and taxis, the city is expected to become fully compliant with legal limits on NO2 by 2025. Research has suggested that without such measures, based on the

CITIES beset by illegal levels of dirty air are looking to London this week, as the first stage of a major anti-pollution scheme kicks off. The Ultra Low Emission Zone (ULEZ) is designed to clean up the UK capital’s air, which research released last week suggested has caused more than 4000 hospital admissions over the past three years by aggravating asthma. It aims to reduce levels of nitrogen dioxide (NO2), an invisible but toxic gas produced by some cars. “London’s Ultra Low Some 100,000 vehicles enter Emission Zone is the most central London daily. From Monday, ambitious emission control drivers doing this had to pay £12.50 a scheme in any megacity” day if their car doesn’t meet certain emissions standards. That will typically rate of decline in NO2 levels between mean any diesels older than 2015 and 2010 and 2016, that milestone would petrol models pre-2005. have taken 193 years to reach. A more significant step comes in City Hall officials argue that October 2021, when the zone will be knowing the ULEZ is coming has expanded to an area 28 times the size, already had an impact, saying that the with 1.4 million people living in it. number of compliant vehicles entering London’s scheme is considered central London in the past two years genuinely world-leading. “The ULEZ is has grown from 40,184 to 55,457. the most ambitious emission control scheme in any megacity. The spotlight Still, that change could have happened naturally as people get rid of older is on it, as hundreds of other cities

cars, without the stick of the looming charge. There should be fewer cars in central London too, with an expected 5 per cent reduction in vehicles in the first year, as some drivers opt for alternatives such as walking, cycling and public transport. There are limits to what the zone will do, however, because even electric vehicles still generate particulate pollution as their tyres break down. One of the ULEZ’s biggest repercussions could be to spur action by other UK towns and cities. While some, such as Nottingham and Derby, have already opted against a clean air zone, others, such as Birmingham, are pushing ahead with one that would cover private passenger cars. The technology used to enforce the zone – cameras and number-plate recognition – is likely to be similar for other cities, says David Carslaw of consultancy firm Ricardo Energy and Environment, but London already has infrastructure that is used to charge for car access. The scheme’s largest impact may be creating political space to argue for charging drivers on health grounds. The difficulty will be that although Londoners have good access to public transport, many other cities are more car-dependent. “It will be important that London can show that the pain it bears of such schemes results in a tangible improvement in air quality,” says Kelly. ■ 13 April 2019 | NewScientist | 23

APERTURE

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Wooden wonders FROM mighty maples to small shrubs, woody plants are even more striking when viewed from the inside. Hidden beneath the bark is a lush world of cells that reveal the secrets of these plants. This image shows a form of plant warfare, magnified 400 times. The large blue objects are root-like structures from the parasitic plant mistletoe penetrating the wood of a maple tree. Along one of the tree rings are red and green dots, which are chemicals produced by the tree to prevent further mistletoe invasion. To create this coloured close-up of tree cells, the wood was thinly sliced and then stained to highlight the main tissues: lignin in red and cellulose in blue. It is part of a collection of images of woody plants from diverse environments – more of which are shown on the following two pages – put together by Alan Crivellaro at the University of Cambridge. “I experience the beauty of these images every day and I want to share them with other people,” he says. Crivellaro studies how plants change their anatomy according to their growing conditions. He also uses magnified images of wood cells to identify illegally traded timber and to investigate archaeological remains. Alison George

Photographers Alan Crivellaro and Fritz Schweingruber alancrivellaro.com

13 April 2019 | NewScientist | 25

APERTURE

1

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2

3

1 Wood from a 1100-yearold canoe found in an Italian riverbank. It is a pirogue, a type of canoe carved from a single trunk. The lignin and cellulose have degraded, so don’t stain respectively red and blue as in the other images. 2 A tangle of cells from a deformed, woody lump, or “burr”, on the trunk of a European beech.

4

3 Two water transport tubes in wood from a “tree of heaven”. One is blocked by gum to defend against fungal or insect invasion. 4 Complex structures in the bark of a European beech, with a wood layer in red at the bottom. 5 The water transport tubes in this white mulberry tree are blocked by blue-stained cells, a sign that the wood came from the innermost part of the tree and is now too old to transfer water. 6 A cross section of the stem of purple mountain saxifrage, a small plant found in many cold and mountainous places. Its thick cork bark protects the stem from frost. 6

5 13 April 2019 | NewScientist | 27

YOUR MYSTERY MICROBIOME

EIKO OJALA

The human body is home to microbes so strange that they are rewriting the tree of life, and this biological “dark matter” profoundly influences our health, discovers Colin Barras

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COVER STORY

RIC BAPTESTE is on a hunt for life, but not as we know it. He doesn’t think we have to sift through Martian soils or trawl lunar oceans to find these entities. His hunting ground is far closer to home: the human body. “Biology is full of surprises,” says Bapteste, an evolutionary biologist at the Pierre and Marie Curie University in Paris. “Since we have not yet exhaustively sampled all the DNA in the world, there is still room for finding rare, strange creatures.” A realist might say that Bapteste’s mission is doomed to fail. After all, we are in the 2010s, not the 1710s. It is unthinkable that biologists can unearth new divisions of life on Earth – let alone make those discoveries in the intimately familiar environment of the human body. They would be wrong. Recent research shows that our bodies are home to microbes unlike anything science has encountered before – some so alien that they are rewriting the tree of life. What’s more, this microbial “dark matter” could be having a profound effect on our health, for better and worse. The body is home to some 39 trillion microbes, which outnumber our 30 trillion human cells. Our skin has a billion bacteria per square centimetre. Earlier this year, a study found that as many as 2000 different species can thrive in the human gut – although a smaller subset of these live in or on any one individual. For years we assumed these microbes were harmful, but we now know that many of them are actually our allies, closely linked with our health and well-being (see “The human zoo”, page 30). Thanks to new technology, we can now study them in unprecedented detail. Until a few decades ago, microbiologists had to grow microbes in the lab before they could identify and study them. However, the vast majority of microbes can’t be cultured this way, seriously limiting the scope of our understanding. Today, we can get around this problem using metagenomic sequencing,

E

a technique used to identify microbes from their DNA – in a sample of human faeces, for instance – even if the microbes won’t grow in culture. Once snippets of DNA have been identified, we can use software to reconstruct whole genomes from those fragments. Thanks to this approach, every month seems to bring a new discovery of previously unknown microbes living in or on us. Occasionally, these are truly unexpected. In 2013, for example, a team led by Jillian Banfield at the University of California, Berkeley, and Ruth Ley at Cornell University in New York discovered evidence that our guts are home to a completely new group of organisms – and that they are related to >

THE ECOSYSTEM INSIDE It’s a jungle in there. There

interdependencies,” says

such interactions, it might

is a surprising diversity of microbes living in and on

Jillian Banfield at the University of California,

even be possible to find new  ways to treat diseases that

our bodies. And like jungle species, they interact to

Berkeley. Sometimes this interaction

result from microbial pathogens. Antibiotics have

form intricate ecosystems. The interactions stretch

can trigger disease, such as when oral bacteria are

had a hugely beneficial impact on human health, but

across the three known domains of life – eukaryotes, bacteria and archaea. In our guts, for instance, one 2013 study suggested that eukaryotic Candida yeast degrade starches in our diet, freeing up simpler sugars that Ruminococcus bacteria ferment. Methanobrevibacter archaea then thrive on the waste products released by the bacterial fermenters. “By-products and waste products become resources for other organisms, and the system functions only through those

parasitised by strange, tiny bacteria and together seem to dodge the immune system (see main story). But it can keep us healthy too. In your mouth, Candida albicans yeast can trigger nasty infections, but through interaction with a bacterial species called Fusobacterium nucleatum, the yeast is kept in a relatively benign form. This means it is less able to kill cells of the immune system and become dangerously overabundant in the oral microbiome. As we learn more about

they are blunt tools. “They are generally not specific, so they kill most bugs and not just the ones you want to kill,” says Xuesong He, a microbiologist at the Forsyth Institute in Cambridge, Massachusetts. We may be able to target specific pathogens by disrupting their vital ecological interactions with other species in the microbiome. “The idea is to use the power of the microbes that live with the pathogens,” says He. “Using the microbiome to do the treatment.” 13 April 2019 | NewScientist | 29

THE HUMAN ZOO Our bodies are home to an astonishing variety of species, which can influence our health and even our minds. Here is a snapshot: EYELASH MITES Shaped like a slug with eight legs, Demodex mites are a relative of spiders and grow up to 0.4 millimetres long. Two species live on the human face, and can cause skin problems such as rosacea. OBESITY BACTERIA The average human gut contains about 160 species of bacteria, weighing about 1.5 kilograms in total. In Western populations, bacteria from the Firmicutes and the Bacteroidetes groups dominate. They break down carbohydrates and make essential nutrients like B vitamins. People with obesity seem to have higher than normal levels of Firmicutes – and lower than normal levels of Bacteroidetes. DEATH MICROBIOME Bacteria including Clostridium difficile (which can cause diarrhoea) and Clostridium botulinum (which can trigger botulism) become abundant in the human “death microbiome”, the army of microbes that take over after you die. MIND-ALTERING MICROBES The content of your gut might influence your mental health: people with depression have gut microbiomes containing lower than average numbers of bacteria belonging to the Coprococcus and Dialister groups. ALZHEIMER’S BACTERIA One of the key bacteria involved in gum disease, Porphyromonas gingivalis, may also play a role in causing Alzheimer’s disease.

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cyanobacteria, a well-known type of microbe critical to the evolution of complex life. The team named these newly found microbes Melainabacteria, after the nymph of dark waters from Greek mythology. The connection of Melainabacteria to cyanobacteria was intriguing: the latter are, as far as we know, the only organisms ever to develop a form of photosynthesis that generates oxygen as a by-product (plants have this ability only because they incorporated cyanobacteria into their cells). This innovation transformed the planet’s atmosphere and paved the way for complex life. But how cyanobacteria have evolved has been a bit of a mystery, largely because we have struggled to find related microbes.

The facilitators of life Melainabacteria plug that gap. They have already helped microbiologists and geologists to argue that oxygen-generating photosynthesis evolved relatively late in the history of life. What’s more, they may play an important role in human health too. A 2018 study revealed that people with Parkinson’s disease have fewer Melainabacteria in their gut than those without the condition. The microbes might protect us by outcompeting cyanobacteria, which generate neurotoxins, for nutrients and preventing them from gaining a toehold. This finding hints at something important about human microbiomes: they are complex ecosystems containing a range of microbes interacting with one another (see “The ecosystem inside”, page 29). This diversity is plucked from all three of the major branches, or domains, of the tree of life. The cyanobacteria, for instance, belong to the bacterial domain. Our bodies are also home to microbes that look superficially like bacteria but actually belong to a distinct domain called the archaea, commonly found in extreme environments such as hot springs. The body was once thought to be an unlikely habitat for these simple organisms, but last year a team reported that archaea are as abundant as bacteria in the human appendix and nasal passages. Our bodies also play host to a huge number of microbes – including fungi – from the domain of complex, eukaryotic life that also contains animals and plants. But is it possible that within us lie completely new life forms, microbes that don’t fit within these three known domains?

Bapteste has reason to believe so. In 2015, he and his colleagues sifted through gene sequences from faecal samples and found DNA that was so unusual it hinted at the existence of a mysterious fourth domain of life. The work is some way from solid proof that our bodies are home to such weird organisms, but one recent discovery suggests the idea isn’t as far-fetched as it might sound. Back in 2010, a team exploring the life forms living in our mouths – the human oral microbiome – found genetic material belonging to two rare groups of bacteria, known simply as TM7 and SR1. These had first been found a few years earlier in a peat bog and in river sediment, respectively. By 2013, a group had pieced together essentially complete TM7 genomes from a wastewater treatment plant. Another team, led by Banfield, had done the same for TM7 and SR1 microbes living in groundwater. They discovered that all of the genomes were curiously small – roughly a quarter of the size of the genome of Escherichia coli bacteria, which are commonly found in the gut and the wider environment. As a consequence of being so small, the genomes seemed to lack some genes thought to be essential for independent life. This could mean they belonged to bacteria that survive only in intimate symbiosis with other cells that give them what they can’t make themselves. Since then, we have learned a lot more about these odd bacteria. In 2015, Banfield’s team used electron microscopy to show that some are so small that they are on the cusp of being impossible. Individual cells tend to be no more than a few hundred nanometres in length, which is about as small as biologists have calculated cells can be and still function. The same year brought even more unexpected news. Banfield and her colleagues studied almost 800 bacteria with small

“The bacteria are so small that they are on the cusp of being impossible” genomes (including TM7 and SR1). They realised that the bacteria belonged on a single evolutionary branch, which was given the working name of the Candidate Phyla Radiation (CPR). What’s more, the CPR branch was a staggeringly stout one: Banfield and her colleagues suspect that the CPR account for as much as half of bacterial diversity. The upshot is that we really do seem to have

Updated tree of life With the advent of new genetic techniques, the tree of life, traditionally split into three domains – bacteria, archaea and eukaryotes, keeps getting new branches, including the recently added CPR subdomain

Candidate Phyla Radiation (CPR) Bacteria with small genomes such as TM7, SR1 and GN02

BACTERIA Single-celled organisms including cyanobacteria and E. coli

CINDY J. CASTELLE & JILLIAN F. BANFIELD

ARCHAEA Microbes with no nucleus, often found in extreme environments. Includes Methanobrevibacter

EUKARYOTES Animals, plants and fungi, including Candida yeast

a newly recognised set of very unusual microbes in our bodies. “We think it’s a new player… these ultra-small bacteria with tiny genomes that we’re just learning about,” says Jeffrey McLean at the University of Washington in Seattle. They may not be distinct enough to qualify as a fourth domain, but the CPR “subdomain” has revolutionised our picture of the tree of life (see diagram, above) and profoundly affected our thinking about human microbiomes. There are, in fact, three different types of CPR bacteria that we know of in the human body – TM7, SR1 and a third called GN02. So far, they have been found in the human mouth, gut and vagina and on the skin. Now we know they existed in Neanderthals too. Studies of mineral deposits taken from 48,000-year-old Neanderthal teeth found several strains of CPR bacteria, including one called TM7x. What exactly are these bacteria doing? An answer is beginning to emerge, and it isn’t good news. CPR bacteria usually comprise no more than 1 per cent of microbiome populations, but can be far more abundant in people with certain illnesses, including inflammatory bowel disease. In people with severe gum disease, 20 per cent of the oral microbiome may be composed of CPR bacteria. But are these mystery microbes actually causing these health woes? To answer that, McLean and Xuesong He, now at the Forsyth

Institute in Cambridge, Massachusetts, decided to take a closer look. In 2015, they led a team that managed to grow a strain of TM7 taken from the human mouth, making it possible to study the microbes’ biology and behaviour under the microscope. This strain – TM7x – remains the only CPR bacterium that has been successfully cultured to date.

A cloak of parasites It wasn’t easy. McLean and He’s team found they could only grow TM7x in a co-culture that also included a strain of another oral bacterium called Actinomyces odontolyticus, which can itself cause inflammatory disease if it becomes overabundant in our microbiomes. Studying the cultures under the microscope revealed why the two must be grown together: the tiny TM7x cells are parasites that bind themselves to the surface of the larger A. odontolyticus bacteria. This kind of microbe-on-microbe parasitism has been seen elsewhere in nature, but never before within us. “Having a bacterium parasitise another bacterium in our bodies is a new finding,” says McLean. But even though McLean and He have evidence that TM7x can kill A. odontolyticus cells, the parasitic relationship is a strange and complex one. Intriguingly, when A. odontolyticus are parasitised by TM7x, they gain the ability to dodge

New life: An example of a recently discovered group of ultra small bacteria next to a bigger microbe

detection by our immune system. This might help explain the link between CPR bacteria and conditions including gingivitis and inflammatory bowel disease. These are caused by bacteria that are standard components of the healthy human microbiome, but that overwhelm our immune system if they become too abundant. Perhaps being parasitised by CPR microbes gives certain bacteria the ability to avoid detection by our immune system and helps them become abundant enough to increase inflammation – although that is an idea that hasn’t yet been tested, says McLean. “The discovery of the CPR bacteria was a big surprise,” says Bapteste – and it is one with big possible implications. After all, if we have only just realised that our microbiomes are home to a previously unknown subdomain of life, who knows what additional life forms may be lurking within us. Bapteste is realistic, and recognises that identifying them will take time and won’t be easy. “Finding novelty is always far more difficult than finding more of the creatures we already know,” he says. “It’s going to be a long quest.” ■ Colin Barras is a writer based in Ann Arbor, Michigan 13 April 2019 | NewScientist | 31

We are preparing to send spacecraft to another star system, 4 light years away. It’s a monumental undertaking, as Gilead Amit reports

Prepare to make the jump to light speed* *20 per cent of

F YOU left Earth now, travelling at the speed of light, you would get to the moon before reaching the end of this sentence. Getting to the sun itself would take 8 minutes at this speed. The furthest tendrils of human activity, Voyagers 1 and 2, which launched in 1977 and are only now reaching the outer edge of the solar system, would be overtaken by this time tomorrow. But getting to Proxima Centauri, our solar system’s nearest star, would take four years and three months. And that is travelling at light speed, a velocity well beyond our reach. The quickest we could currently get to Proxima Centauri, using our fastest rockets, is 80,000 years. Small wonder interstellar travel hasn’t been much of a priority. But what if we could get to the Proxima system in 20 years? At a highly publicised press conference in 2016, a team claimed to have assembled the scientific know-how to make a mission to Proxima Centauri not only possible, but doable within our lifetimes. Breakthrough Starshot, backed by a Silicon Valley billionaire and tapping into NASA expertise, provoked mostly cautious enthusiasm. Three years later, with a better sense of the challenges and published research to support the team’s optimism, the plans are gathering speed.

I

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If they succeed, we could be a decade or two away from embarking on the most ambitious mission of all time, and discovering the truth about a solar system different from our own. So what are the key challenges? Getting to a distant solar system within a human lifetime means travelling fast. Very fast. And the pool of available technologies capable of propelling a spacecraft at a significant fraction of the speed of light is pretty limited. For decades, there has been only one serious candidate. “There’s no alternative to using

“We all have these existential dreams in life. What he said was, ‘show me the way’” light as a fuel if your mission really is to go interstellar,” says Harry Atwater of the California Institute of Technology and a member of Breakthrough’s advisory committee. “A few other options, like fusion drives, have been discussed, but aren’t on the table.” Just as incoming wind can propel a boat by exerting pressure on a sail, beams of light can also drive motion. Make a spacecraft light enough, strap a sail to it, point a powerful

light source at it and out in the vacuum of space it could rack up some serious speed. Solar sails, designed to harness the light of the sun, have been kicking around scientific doodle pads for centuries. Johannes Kepler is credited with inventing the idea in a letter to Galileo. But powerful as the sun’s rays may be, they can’t propel anything to near light speed. For that, you need lasers capable of illuminating a given point with millions of times more energy than sunlight alone. In 2009, Philip Lubin had just started a new project at the University of California, Santa Barbara. His primary goal was to design giant laser arrays that could protect our planet by blasting incoming asteroids into smithereens. But he soon recognised their potential for space travel at “relativistic velocities”, those approaching the speed of light. “Literally within a week,” says Lubin, “came the idea that one could use them for relativistic propulsion.” By 2014, Lubin had secured funding from NASA to work on that idea full time. Doing the rounds of conferences, he had a chance to speak to Pete Worden, former head of NASA’s Ames Research Center in Silicon Valley. Worden was interested in Lubin’s work, and asked him to send over a paper he had been working on. “Pete >

SAM CHIVERS

13 April 2019 | NewScientist | 33

FIRST SHOTS IN AN INTERSTELLAR WAR? On the list of things worth worrying about, you might not think that stumbling into an interstellar war with aliens would be too near the top. But according to many luminaries, from Stephen Hawking to Elon Musk and science-fiction writer Cixin Liu, it represents a real possibility. The argument centres on the danger that human activity in interstellar space could alert unfriendly aliens to our presence and to Earth’s location. Some believe that Breakthrough Starshot itself (see main story) could be regarded as an act of war: a tiny armada crossing the empty space between galaxies with evil intent. For Doug Vakoch, president of San Francisco-based METI International, which seeks to communicate with extraterrestrial intelligence, the notion is “preposterous”. If there are advanced civilisations where we are headed, he says, they won’t be able to detect and verify the nature of the tiny craft. He compares it to ‘Oumuamua, a mysterious recent arrival in our solar system that sparked widespread debate about whether it was an asteroid or a solar sail. “If there are any technologically savvy inhabitants of Proxima b,

of TV broadcasts that have leaked into space. Not only is Vakoch not worried,

WE COME IN PEACE Jill Tarter of the SETI Institute in California thinks humanity isn’t yet developed enough to take on a transmission project. “Any finite transmission will pass over the intended recipient for a finite time and they must be looking at us in just the right way during that finite time, or the message will be missed,” she says. Tarter, who was the inspiration for Jodie Foster’s character in the movie Contact, says messaging must be a long-term strategy, so that when a civilisation starts to explore their sky, the message will be waiting for them to discover. “It’s going to be a while before we can execute on 10,000 or 100,000-year plans, but when we’ve managed to become an advanced technological civilisation ourselves, then we should transmit.” Liu, whose Remembrance of Earth’s Past trilogy deals with the consequences of contact with aliens from Proxima b, sees the value of searching for extraterrestrials, but warns of stumbling into a crisis. “We  are not an advanced civilisation,” he says. “We are like toddlers, and even toddlers can cause big problems.”

he is keen to reach out directly. He

Rowan Hooper

they won’t make first contact with Earthlings by detecting nanoprobes whizzing past their star system at a fifth the speed of light,” says Vakoch. Indeed, any advanced aliens probably know about us already, from decades

emailed me and asked if he could send it to a friend,” says Lubin. “I said sure, send it to whoever you want.” That friend was Yuri Milner, a Russian-born billionaire who had recently appointed Worden as head of a new foundation designed to tackle some of humanity’s biggest challenges. One of those was to travel to another solar system. The mission would eventually be called Breakthrough Starshot, and with Lubin on board Milner had the missing piece needed to pursue his goal. “We all have these existential dreams in life,” says Lubin. “What he said to me was ‘show me the way’.”

thinks we should actively signal to potential aliens, using the laser array as a beacon to transmit messages. “My dream is that once Starshot’s lasers are up and running, these Earth-based light beams will propel the light sails,” he says, “while also bearing our encoded messages to any extraterrestrials at the other end.”

Shoot for the stars

LINUS PLATT/ALAMY

The Allen Telescope Array in California conducts searches for alien intelligence

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In April 2016, the project was officially launched. At the One World Observatory in downtown Manhattan, in the presence of physicists Stephen Hawking and Freeman Dyson, and astronaut Mae Jemison, Milner announced the mission to Proxima Centauri. Lubin’s plan was breathtaking in its ambition. Hundreds of tiny spacecraft, each equipped with a light sail and the minimum amount of hardware needed to record and transmit information, would be deployed in orbit. An enormous array of lasers on Earth’s surface would then accelerate them to about a fifth of the speed of light – some 60,000 kilometres per second – a velocity thousands of times more powerful than anything experienced by conventional spacecraft. Twenty years later, whichever of the craft had successfully navigated the debris-strewn obstacle course of outer space and reached Proxima Centauri would beam back images of the star system and any potentially habitable planet as they zipped past. For Avi Loeb, an astronomer at Harvard University who chairs Starshot’s advisory committee, there is no reason the project shouldn’t work. “Nothing contradicts the laws of physics,” he says. That’s not to say it will be easy. The initiative’s researchers have to engineer a fabric that can absorb gigawatts of laser light without spontaneously combusting. They have to build electronics that are light enough to cross interstellar space, but sophisticated enough to beam images back across 4 light years. They need to ensure that the lasers on Earth are accurate enough to hit the small light sails accelerating away from Earth at immense speeds and that the spacecraft arrive on target. And then, of course, they have to actually construct this power source. “What

“The Starshot light sail needs to reflect 99.999 per cent of light hitting it”

ESO/M. KORNMESSER

Proxima b, the closest known exoplanet to Earth, orbits Proxima Centauri

we’re calling for is a laser system that’s the largest ever built by humans,” says Atwater. As Loeb points out, governments may not be best pleased if what are effectively superweapons suddenly appear on their doorsteps. But Loeb considers political considerations a bridge to be crossed sometime in the future. “We want to focus first on the challenges in terms of the physics,” he says. The team’s first priority is the light sail. Most of the necessary technical specifications are already laid out, and the challenge will be finding or making a material that fits the bill. The current plan calls for a fabric that covers maybe 10 square metres, yet weighs no more than 1 gram. That means a thickness of less than 100 nanometres, tens of times thinner even than spider silk. Producing such gossamer-like membranes is perfectly achievable. Ensuring they survive a concentrated laser blast, though, is something else entirely. The key is for the material to absorb almost none of the incoming light. “You’re trying to build something that acts like a mirror,” says Atwater. But whereas the shiniest metals reflect around 99 per cent of the light that hits them, the Starshot light sail needs to reflect more than 99.999 per cent. Finding a material with the right combination of low density, high reflectiveness and low absorption isn’t simple. Two promising candidates appear to be silicon dioxide, also known as silica, and a material called molybdenum disulphide that can be manufactured in sheets only an atom

thick. A third candidate is diamond, says Loeb. “Imagine having a big diamond in the sky and pushing it with a laser beam. That would be quite remarkable.” As Starshot’s light sail specialist, Atwater is trying to encourage research on these and other materials in the hope of identifying the

Close to home Proxima b, the nearest exoplanet to Earth, orbits closer to its star than Mercury, our solar system’s innermost planet, does to the sun. Proxima Centauri is smaller and cooler than the sun, so its planet could still host life – if it can survive the frequent stellar flares

Our solar system

SUN

Mercury’s orbit

20 million km (0.13 AU)

Proxima system

PROXIMA CENTAURI Proxima b orbit Habitable zone

Alpha Centauri A Alpha Centauri B Proxima Centauri SUN Light years

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ideal substance. “Both in our lab and others around the world, people are tooling up to build experiments to test these materials,” says Atwater. “Within the next year or so, we’ll have results.” Progress is also being made on building the laser array. According to Lubin’s 2016 road map, the Starshot mission will need a system capable of generating around 60 gigawatts of power. That’s equivalent to 20 nuclear power plants. By comparison, a standard laser pointer racks up 5 milliwatts and a laser beam strong enough to dazzle pilots needs only a few watts of power. The system planned for Starshot would be capable of pushing asteroids off course. Applied to a minuscule spacecraft with a laser sail, it could accelerate it to a fifth of the speed of light within 10 minutes, allowing it to coast past Mars 20 minutes later, pass Pluto within 7 hours and get to Proxima Centauri in two decades. The remarkable thing about making a laser of this scale is that the technology already exists. “The problem is not producing lots of power,” says Lubin, it is the difficulty of achieving what is known as parallelisation. Rather than building one enormous laser, the goal is to create an array of weaker lasers and thread their power together. “In the past, that was demonstrated with one pair of beams,” says Loeb. The challenge is to do that with several million. If this effort starts to come together, the team plans to move on to building > 13 April 2019 | NewScientist | 35

the spacecraft. Known as StarChips, these tiny craft will be marvels of engineering. Weighing in at less than a gram, they will need an on-board power source, miniature thrusters for course correction, cameras for documenting their destination and a powerful transmitter to beam those images back to Earth.

A StarChip leaving Earth. As yet, artist’s impressions are all we have. Bottom left: a Sprite, the smallest satellite yet launched into orbit

Combining all that tech on a tiny spaceship designed to be flung across interstellar space is no mean feat. “We have gram-scale spacecraft, but right now they’re at the Sputnik level of capability,” says Zac Manchester of Stanford University in California, a specialist in nanosatellite design and another member of Starshot’s advisory committee. At the moment, he sees the long-distance communication back to our planet as the major hurdle, potentially requiring a massive ground station on Earth coupled with a highpowered transmitter on the tiny spacecraft. When asked how long he thinks it might take to get a fleet of mini satellites ready for launch, he hedges his bets. “I think that the spacecraft end of it is a lot easier than the laser end,” he says. “I would say a decade, maybe, is the timescale over which you could figure it out.” If the team succeeds, by 2030 all the various technologies will be sufficiently developed for the feasibility of the project to be experimentally demonstrated. Once that is done, an initial prototype must be built, ahead of the full system. The mooted price tag? $10 billion. The ideal timeline? Twenty years. “This is an enormous project on the scale of an Apollo-like programme,” says Lubin. Those outside the core team are cautious in their criticism. “I don’t see a fundamental limit that would make it impossible,” says Malcolm Macdonald, a space technology

36 | NewScientist | 13 April 2019

BREAKTHROUGH STARSHOT

Existential significance

“Once we get into interstellar space we will get a message saying ‘welcome’” engineer at the University of Strathclyde, UK, “but the challenges are, well, of note.” Ciara McGrath, who works with Macdonald, highlights the extraordinary specifications of the proposed laser system, which will need to generate five times more power than the largest power station on Earth. “It’s something that I personally would love to see,” she says, “I guess my question is: is it worth it?” Rather than rushing ahead with such an ambitious mission before we know it can succeed, she suggests waiting until the necessary technology is further along. “There’s certainly an argument to be said that maybe we should be putting money into things that really help people on Earth,” she says. Loeb has little patience for such arguments. “A lot of human activity is based on selffulfilling prophecies. If you tell yourself that you can’t do something, then you will never do it,” he says. “Don’t put chains on your feet and you will reach very far away.” He regards the project as being of almost existential significance. “We cannot stay forever on this planet,” he says. “The only question is the timescale.” The 2016 discovery of an exoplanet orbiting Proxima Centauri – making it the nearest one to Earth – added to the excitement surrounding the project. Later research indicated that the star is prone to nasty

outbursts of X-rays and UV radiation, with its planet, Proxima b, unlikely to be habitable. But even if it does turn out to be unfit for humans, the chance of exploring any neighbours it might have is too good to miss. And then, of course, there is the possibility of encountering alien life (see “First shots in an interstellar war?”, page 34). Once outside the confines of our solar system, Breakthrough’s spacecraft will be well placed to spot the signatures of any other spacefaring civilisations. “My personal belief is that there’s a lot of traffic,” says Loeb. “I would think that once we get into interstellar space, we will get a message saying ‘welcome’.” Even if that prediction fails to come about, the mission will be a vital first in the history of space travel. “People are really called by grand challenges,” says Atwater. “This is a really exciting grand challenge.” “It’s hard not to get excited about something like this,” says Manchester. Even for those not involved, like Macdonald, the mission could yield astonishing benefits. “I see the point of a moonshot as being as much about what it inspires en route as the destination itself,” says Macdonald. “You can never be sure where you will end up and we should embrace the journey.” ■ Gilead Amit is a features editor at New Scientist

P H O T O E S S AY

FOUND WORLDS

For decades, those seeking to document Colombia’s unique biodiversity faced daily threats of kidnapping and death in its conflict zones. Those dangers are now fading, but biologists are in a race against time to preserve the newly discovered riches. Words by Luke Taylor. Photos by Felipe Villegas Vélez, Humboldt Institute HE AK-47 rifles hanging at the waists of the camo-clad visitors suggested they had little interest in birds. For ornithologist Andrés Cuervo, the knock at his cabin amid the isolated mountains, rivers and waterfalls of the Serranía de San Lucas region heralded just one of many unnerving encounters that punctuated his work. “Nobody knew the guerrillas were there, but they knew everything about us,” he says. For decades, this region of northern

T

Colombia was one of many disputed in a civil war that left 260,000 people dead and 7 million displaced. What was a human tragedy proved a boon for biodiversity, however, as the conflict zones were spared the exploitation that ravaged similar environments elsewhere. Now, with the conflict largely at an end, at least officially, biologists such as Cuervo are returning in force to discover, record and understand the country’s astonishing lifeforms,

and perhaps to unlock the secrets to novel medicines. But new threats are gathering force. They may not have much time. Colombia is by some measures the most biodiverse nation on Earth. It lags behind only Brazil in the total number of species it hosts, but has more species per square kilometre. It is thought to be home to nearly one in 10 of every type of the world’s flora and fauna, and there are more kinds of bird, amphibian and >

13 April 2019 | NewScientist | 37

ALL PHOTOGRAPHS FELIPE VILLEGAS VELEZ/BANCO DE IMÁGENES AMBIENTALES (BIA), INSTITUTO ALEXANDER VON HUMBOLDT

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butterfly here than anywhere else. That is down to geography: bordering both the Atlantic and the Pacific oceans, the country lies at the northern end of the Andes mountains, which splits into three parallel ranges, the Western, Central and Eastern Cordilleras. This creates a unique patchwork of environments, from boggy moors to dense Amazonian forests and ice-capped peaks to Caribbean mangrove swamps. The remote Serranía de San Lucas massif lies in the Bolivar department at the northern tip of the Central Cordillera. Its highly diverse tropical rainforest marks where the mountains meet the Caribbean plains. For Cuervo, head of collections at the Humboldt Institute headquartered in Colombia’s capital, Bogotá, what drew him there despite the risks was the region’s 350-odd known species

38 | NewScientist | 13 April 2019

of bird. Similar riches attracted colleagues working in other fields. The researchers would go into conflict areas across Colombia in small groups, hoping for permission to carry out their work from whichever armed group was dominant. Cuervo lost count of how often he was detained. After that knock on the door in 2001, he and his team were held for two weeks. “You never knew if you would be there for years,” he says. Another time, in a remote valley, he recalls machine gun fire cracking “like popcorn” above his head from all directions. “It was a close one,” he says. Then came the peace accord, signed in 2016 by the government and the largest rebel group, the Revolutionary Armed Forces of Colombia, or FARC. Government officials and the public can now enter the 40 per cent of the

Previous page: Colombia’s northern mountain ranges in the Antioquia region are a hotbed for biodiversity, for the production of coffee and coca – and for conflict

Above: The many rivers that cut through the mountains create microhabitats home to endemic species, among them an as-yet unnamed colour-changing lizard that climbs with its tail (top right). The recently discovered eyeless catfish Thrichomycterus rosablanca inhabits a series of caves in the Santander region (middle right)

P H O T O E S S AY

country where before they would have hesitated. “It’s not that nobody ever went to these places”, says Cuervo. “But it is [now] a lot easier.” One peace dividend is a programme known as Colombia BIO to document biodiversity across the country. With the support of institutions such as the Royal Botanic Gardens, Kew in London, more than 100 expeditions will create a catalogue of flora and fauna. The aim is “to value biodiversity, understand it, and from this create sustainability”, says Henry Alterio, the programme’s director. And also to exploit it, tapping into animals, plants and fungi for biotechnology advances, such as finding new drugs. Some expeditions are guided by former FARC guerrillas, utilising their unique knowledge of the forests. In 20 trips in the past two years, 174 possible new species have been found,

133 of them probably found only in Colombia. With more expeditions to come, and many more species yet to be documented from samples already taken, this could be the tip of a very large iceberg, says Cuervo. The Humboldt Institute’s lab in Villa de Leyva, some 120 kilometres north-east of Bogotá, is a launch pad for many of these trips. There, the shelves of herpetologist Andrés Acosta-Galvis overflow with specimens of snakes and frogs gathered in the field. A crate full of jars holds the latest arrivals. “Each of these could be a new species,” he says. “It is just getting the time to process them all.” Among Acosta-Galvis’s recent finds are a “gladiator frog” that uses spikes on n its hands h to fight rival males, a lizard that climbs with its tail and changes its colours to blend in like a >

Colombia’s troubled jewels Some of the most biodiverse areas in the country have suffered decades of conflict

Bolivar department Serranía de San Lucas Santander department Medellín Antioquia department

Villa de Leyva Bogotá

COLOMBIA

Vichada department

13 April 2019 | NewScientist | 39

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40 | NewScientist | 13 April 2019

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Left: A Humboldt Institute research expedition explores a cave in the Santander region

Right: The Upper Orinoco tree frog Boana wavrini was found in the forests of the Vichada region near Colombia’s border with Venezuela, 280 kilometres north of its previously known range

chameleon (pictured on page 39), a green-boned frog that sounds like a goat and a snake that emits a smelly excrement when threatened. Meanwhile, his colleague Carlos DoNascimiento, an ichthyologist, is excited by a discovery made in a remote series of caves in the Santander department. To the untrained eye, Trichomycterus rosablanca, a cave-dwelling catfish, isn’t particularly interesting. But look closer, and you see that it has adapted so well to turbid waters with no light that it is not only blind, but eyeless. It has also developed a form of teeth outside its mouth that allow it to scale rocks to survive rapid currents. The fish shows how disparate topographies and the stability of tropical ecosystems have allowed for such evolutionary changes, and how the lack of human interference has permitted their survival. DNA analysis shows T. rosablanca’s closest relative has eyes, but lacks pelvic fins. “Sequencing the genome of these two species will allow the identification of the genes that are responsible for the development of eyes or fins,” says DoNascimiento. Those results can be extrapolated to other vertebrate species, including humans. That might allow a better understanding of some genetic anomalies related to blindness in people, for example, providing

clues to potential therapies. The new wave of species could also help trace not only their history and distribution over time, but also answer questions such as the course of past climate change, and when South America divided from North America. “It’s like entering the scene of a crime, what we do is find the past by using the clues of the present,” says Cuervo. But those clues are in increasing danger of being erased. FARC had strict environmental policies, for example imposing heavy penalties on those who cut down forest without permission. When it demobilised, annual deforestation in Colombia jumped by 44 per cent in a year, mostly in previously FARC-held areas where cattle production boomed and poor farmers or organised mafias cut≈or burned forest in the hope of claiming the rights to the land. Nor has the violence entirely disappeared. Peace talks with the second-largest rebel group, the National Liberation Army or ELN, are intermittent and inconclusive. FARC dissidents who refused to hand in their weapons are now estimated to number 2800. In September, three geologists were killed by FARC dissidents in the Antioquia region, home to Colombia’s second city Medellín. Other guerrilla groups are believed to be gaining strength thanks to a boom in the cultivation of coca,

cocaine’s base ingredient, and by the turmoil in neighbouring Venezuela, which serves as a lawless bolthole. “It is killing the hope that the peace accord provided,” says Cuervo. The very reason for Colombia’s great biodiversity may now prove to be its weakness. Thousands of years of microhabitat stability for tropical creatures means that they are diverse, “but not especially adaptable”, says John Douglas Lynch, a herpetologist at the National University of Colombia in Bogotá. “If they cut down the forest, 90 per cent of amphibians and 70 per cent of reptiles disappear,” he says. “The cost of that is horrendous. Entire ecosystems will die.” Lynch, who has been kidnapped twice, caused controversy in 1993 by naming a species of olive-green forest stubfoot toad Atelopus farci, after the group whose activities had unwittingly protected it. Now, like many human victims of the conflict, it is missing, presumed lost. Lynch, Cuervo and others are on a mission, well aware of the pressures. “We have a unique opportunity to do justice to the scale of biodiversity Colombia has,” says Cuervo. “It is a race against the clock.” ■ Luke Taylor is a journalist based in Bogotá, Colombia. Felipe Villegas Vélez is a photographer at the Humboldt Institute in Bogotá

13 April 2019 | NewScientist | 41

CULTURE

Green thinking for a crowded planet An unsung eco hero and a “natural capitalist” plot unique paths to 21st century environmental harmony. Fred Pearce explores Kipling to Ken Saro-Wiwa. And he writes beautifully, something fans realised 30 years ago with his first book, Taming the Flood, a still-unsurpassed history of incompetent, often hilarious, British river management. Back then, Purseglove claims he was the UK water industry’s first environmentalist. He helped pioneer flood control systems that stopped pouring concrete to

Working with Nature: Saving and using the world’s wild places by Jeremy Purseglove, Profile Books, and Green and Prosperous Land by Dieter Helm, William Collins

Nature’s resources are at the heart of the idea of natural capital 42 | NewScientist | 13 April 2019

GEORGE CLERK/GETTY

YOU probably won’t have heard of Jeremy Purseglove. But arguably he has done more to protect nature than David Attenborough. We have plenty of environmental warriors keen to face down the engineers who would destroy our “Environmentalists need to natural world. But what we also get off their high horses, need in the Anthropocene are and engineers must work environmental arbitrators and with, not against, nature” conciliators to bridge the divide. Purseglove is one such unsung hero. After a lifetime on the payroll of civil engineering companies, he has written an unapologetic and often moving memoir about interceding for nature. This ranges from plotting a less invasive route for new pylons in Mozambique to mapping patches of rainforest to save in palm oil plantations, and from restoring a corner of the dried-up Aral Sea to designing a road tunnel to save a nature reserve in Surrey, UK. He calls this activity (and his book) Working with Nature. He might have called it Working with the Enemy, given its call to unite industry and environmentalists. Purseglove has seen a lot. A child of the British Empire – his father ran the Singapore Botanic Gardens – he is as at home in Sumatra as Surrey, Kenya as Cambridge. He is also well read, ranging from Vita Sackville-West to George Monbiot, and Rudyard

build defences and gave rivers back their natural floodplains instead. Ever since, he has been helping engineers see the virtues of working with rather than against nature – while also urging environmentalists to get off their high horses and engage in the nitty-gritty of building a world fit for more than 7 billion people. But he is no utilitarian. He sees himself as a planetary gardener, nurturing a human-friendly landscape. He gets angry about land grabs in Africa intended to grow crops for the West rather than feed local people. But he is

nearly as impatient with the environmentalists’ fetishisation of what they think is pristine. Some celebrate the supposedly Pleistocene landscapes of Africa, filled with megafauna. But Purseglove says the “great glory” of rural African areas lies “not in their wilderness quality… but the touching way that there always seems to be a marriage between humanity and nature”. They are, he says, “spiritual landscapes”. Spiritual for him, too. He was born in Uganda, and wonders whether the midwife who brought him into the world followed the tradition of burying afterbirths under ancient trees – and if that explains a yearning to return. While Purseglove wants environmentalists to make common cause with engineers, economist Dieter Helm asks them to grasp capitalism by the horns. Nature is capital to be protected for its economic utility, he says, and without this ultimate resource there would be no economy. Purseglove chronicles life as an Englishman abroad, while Helm, the son of a German prisoner of war raised on the Essex marshes, concentrates on the UK. Though agnostic on Brexit, his book could be read as a manifesto for taking control of a countryside freed from European Union directives. His blueprint for rescuing Britain’s green places is short on place-specific detail. Many an armchair environmentalist could have written a wish list for more woodlands, coastal marshes and protected marine areas, or ideas about curbing pollution and soil erosion, or rescue plans for endangered hen harriers, and

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

“Economic inefficiency is the real villain, such as wrecking land to produce food we don’t need” and access to the countryside. What if natural capital were best protected by locking it away? What if the green accountants decided cleaning up polluted city air wasn’t cost-effective? Do the agendas of ecology, aesthetics, human rights and economics really fit as snugly as he suggests? But Helm is surely right to push against the lazy presumption that the very idea of natural capital is “a neo-liberal conspiracy”. And like Purseglove, he insists that “the environment is now irrevocably man-made”. Welcome to the new Garden of Eden. ■ Fred Pearce is a consultant for New Scientist

It’s all too much Unlike other primates, humans are overwhelmed by the choices facing us, finds Simon Ings

Visit A fortnight of events celebrating Earth Day begins on 16 April at Somerset House in London, with installations and workshops to inspire us to come up with creative responses to climate change.

Watch Satellite cameras have changed how scientists monitor the natural world, and now all of us can see just how fast it is changing, when Earth from Space begins at 9pm BST on 17 April on BBC1.

Read LUCA ANTONIO MARINO

even reintroducing predators such as wolves and lynx. Instead, his contribution is to suggest how to make it happen. His key theme is to characterise environmental destruction as the result not of market economics trumping everything, but of its failure. Economic inefficiency is the real villain, he says. We waste money and destroy “natural capital” by paying farmers to wreck the land to produce food we don’t need. We spend millions cleaning up pollution we should never have created. Business as usual isn’t just bad for nature, it is bad for the economy, too. His proposal is a natural capital authority – perhaps a beefed-up version of the government advisory body he already chairs, the Natural Capital Committee. It would redirect agricultural subsidies to protecting nature and raise more money for clean-up and restoration by taxing polluters and developers. He isn’t always clear how his environmental economics meets his more rhetorical aspirations, such as delivering a “universal right” to clean air, green spaces

DON’T MISS

The Importance of Small Decisions by Michael J. O’Brien, R. Alexander Bentley and William A. Brock, MIT Press

WHAT if you could map all kinds of human decisionmaking and use it to chart society’s evolution? This is what academics Michael O’Brien, Alexander Bentley and William Brock try to do in The Importance of Small Decisions. It is an attempt to expand on a 2014 paper, “Mapping collective behavior in the big-data era”, that they wrote in Behavioral and Brain Sciences. While contriving to be somehow both too short and rambling, it bites off more than it can chew, nearly chokes to death on the ins and outs of group selection, and coughs up its best ideas in the last 40 pages. Draw a graph. The horizontal axis maps decisions according to how socially influenced they are. The vertical axis tells you how clear the costs and pay-offs are for each decision. Rational choices sit in the north-western quadrant of the map. To the north-east, bearded capuchins teach each

other how to break into palm nuts in a charming example of social learning (pictured). Twitter storms generated by fake news swirl about the south-east. The more choices you face, the greater the cognitive load. The authors cite economist Eric Beinhocker, who in The Origin of Wealth calculated that human choices had multiplied a hundred million-fold in the past 10,000 years. Small and insignificant decisions now consume us. Worse, costs and pay-offs are increasingly hidden in an ocean of informational white noise, so that it is easier to follow a trend than find an expert. “Why worry about the underlying causes of global warming when we can see what tens of millions of our closest friends think?” ask the authors, building to a fine, satirical climax. In an effort to communicate widely, the authors have, I think, left out a few too many details from their original paper. And a mid-period novel by Philip K. Dick would paint a more visceral picture of a world created by too much information. Still, there is much fun to be had reading the garrulous banter of these three extremely smart academics. ■

In his new book Nature’s Giants: The biology and evolution of the world’s largest lifeforms (Yale), Graeme Ruxton wonders how large living things can get. Meanwhile, Mark Moffett takes on a behemoth of another sort – human society – in The Human Swarm: How our societies arise, thrive, and fall (Basic Books).

Last chance Collusion is a public art exhibition in Cambridge, UK, that uses theatre, music, dance, sculpture, film and animation to explore our complex relationship with emerging technology. It runs until 22 April.

Play Is fending off a hail of asteroids good for your health? From 18 April on Steam, PowerBeatsVR (pictured), a rhythm-based fitness video game, aims to get you into shape by letting you lay waste to everything.

13 April 2019 | NewScientist | 43

CULTURE

Fragile futures David Attenborough stars in Netflix’s new nature flagship Our Planet. Adam Vaughan takes a look

Philippine eagle chicks (top) and bluefin tuna (right) are both at risk 44 | NewScientist | 13 April 2019

BEN MACDONALD / SILVERBACK/NETFLIX

A YOUNG Philippine eagle sits atop the rainforest canopy, noisily badgering its mother for food. “The chick is very demanding,” says David Attenborough, wryly. But the bird is soon fending for itself, risking death as it flaps precariously along a branch 70 metres high. Finally, we are treated to the soaring sight of its first flight or, as Attenborough puts it, the day when “confidence suddenly matches know-how”. Our Planet, Netflix’s flagship nature series, is classic wildlife TV, with sumptuous visuals and engaging narratives. But what makes it interesting is another strand, where satellite images document the rapid loss of rainforest in the Philippines and Borneo in recent decades. The young eagle survived its first flight, but there is barely enough habitat left for such a super-sized bird of prey to flourish. Fragility is the link: how wildlife and ecosystems fare in the face of human pressure, something prime-time nature series have only recently begun to touch on. “The stability of nature can no longer be taken for granted,” says Attenborough in the first of the eight episodes. The threats to the planet are legion, and the series duly covers everything from the disruption of the weather systems that animals and plants rely on to poaching and deforestation, Arctic sea ice loss and ocean acidification. It is also rich with wonders. There is New Guinea’s twelvewired bird of paradise, which uses

its wire-like filaments to tickle the between monocultures of palm face of a potential mate. And there oil plantations and the richness is a great montage of tropical of primary forests. Attenborough forest ants killed by fungi that warns that the result is the young turn them into zombies. “But,” orangutans we see could be the says Attenborough (and there are last generation in the wild. But the a lot of buts in Our Planet), “the show stops short of blaming our diversity of the world’s rainforests demand for the myriad products is falling at an alarming rate, and we buy that contain palm oil. that is because of us.” Similarly, the effects of climate The series brings home the change feature throughout, but consequences for us too, from the dots are never fully joined to the role forests play in regulating expose humans at the heart of Earth’s climate, to the foods and the pressure. The “frightening medicines they furnish us with. “The show stops short of Frustratingly, though, the role blaming our demand for of the viewer is unexplored, products that contain palm which leads to an odd feeling of oil for destroying habitat” disconnect. We see the contrast

GISLE SVERDRUP/SILVERBACK/NETFLIX

Our Planet, Netflix

pace” of change in the Arctic is examined, from loss of sea ice to spectacular footage of glaciers calving and a huge stretch of Greenland ice breaking away. The carbon emissions, fossil fuel companies and human consumption behind such rapid changes, however, are absent. The degradation of habitats created by humans is mostly offscreen, too, with a few exceptions, such as a bleached coral reef. This aside, there is plenty to like in Our Planet. The diversity of locations and whirlwind tour of the globe puts many a Bond film to shame, and the production is lavish, with a score by turns elegiac, comic and stirring. There are stunning shots, from long, tracking scenes of big cats hunting, to close-ups of abseiling caterpillars and deep sea worms’ jaws emerging to bite urchins. Haunting footage of wolves and forests in the areas around the site of the Chernobyl nuclear disaster illustrate nature’s ability to rebound. At 92, Attenborough remains a master broadcaster, as at home narrating the light relief of dancing birds of prey as he is explaining our unsustainable fishing practices. Kids will love it. Ultimately, though, it is unclear what Our Planet adds to the genre. Most of the species it shows have been covered extensively before, and there is no deep delving into any particular habitat, as in Frozen Planet, or detailed coverage of a species, as in Dynasties. For a show meant to shine a light on “our” impact on nature, people and our responsibility are rarer than the desert elephants and bluefin tuna the show so beautifully depicts. ■

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The science skills most in demand As the UK prepares for a massive increase in R&D spending, which skills are the hardest to recruit for? hen it comes to the science jobs market, one question haunts recruiters and job hunters alike: what skills are most in demand? The answer affects industry, which must find ways to top up skill levels. It affects universities, which bear the responsibility for training the next generation, and it affects prospective employees who need to understand the call for their skills. So New Scientist decided to investigate. In the annual New Scientist salary survey, with scientific recruitment specialists SRG, we surveyed 2750 people working in science and engineering in the UK. Of those, 535 were responsible for recruiting and hiring science and technical staff – a group at the coal face who should know where the demand lies. A full quarter of those recruiters told us that the chemistry skillset was difficult to come by, so chemistry topped the charts for hard-to-get talent in 2018. “This is driven by manufacturing, which hires more chemists and employs more people than R&D in the UK,” says SRG director Kelly Morton. Then came biological sciences (identified by 19 per cent of recruiters), engineering (16 per cent), data analysis (11 per cent), quality control (10 per cent), bio-informatics (9 per cent) and regulatory roles (8 per cent).

W

Significant demand But which of these skills are particularly sought after right now? “The demand for more complex medicines, companion diagnostics, cell and gene therapy is gathering pace, so people working in these areas will have more choice and be able to demand significant salaries,” says Richard Acton, a director at SRG. “High-quality project management skills and a commercial outlook are also key career aspects to develop.” In general, recruiters are finding it harder to recruit than in previous years. A recent survey of employers commissioned by STEM Learning reported that three-quarters of 46 | NewScientist | 13 April 2019

Skill set most difficult to recruit for Percentage of recruiters who identified this skillset as the most difficult to recruit for

Chemistry Biological sciences Engineering Data analysis Quality control Bio-informatics Life sciences Regulatory Manufacturing Material scientist Statistics Project management Physics Programing Information technology Mathematics Data management

25% 19% 16% 11% 10% 9% 9% 8% 8% 8% 7% 7% 7% 6% 6% 5% 4%

Base: All responding who are responsible for recruitment. UK (535) SOURCE: NEW SCIENTIST/SRG 2019 SALARY SURVEY

businesses based around science, engineering and technology found it harder to recruit in 2018, compared with 2017. The survey claims there is a shortfall of over 170,000 qualified workers for UK science and engineering roles. And recruiting could get harder still. In 2017, the UK government committed to boost spending on R&D from 1.7 per cent of GDP to 2.4 per cent by 2027. That could mean an additional £80 billion in funding. To put that in human terms, it means an additional 150,000 researchers, according to John Kingman, chair of UK Research and Innovation, the science funding body that is spearheading this endeavour. As Kingman said in a speech to the Royal Society in October last year: “Where are all these very skilled people going to come from?” This demand is already clear in the job market, says Acton. “Where companies used to have four to five excellent candidates to choose from for a given role, candidates now have four to five job offers to consider,” he says. And that puts job hunters in a strong position. Meanwhile, Brexit is also playing a role. One

of its disruptive effects is a reduction in the number of scientists and engineers from mainland Europe looking to further their careers in the UK. In January, Peter Bruce, vice president and physical secretary of the Royal Society, while giving evidence to the government’s Science and Technology Committee, noted: “It is only in the past two years that when I have advertised for researchers there have been no applicants from the main European countries: France, Germany, Italy and Spain. That has not happened before.” Amid all this turmoil is opportunity: the fact that demand for scientists and engineers is already outstripping supply is likely to be what’s fueling the near-double-digit percentage growth in the average UK science salary, to over £40,000 for the first time in our survey’s 13-year history. That kind of growth looks set to continue. ■ Sean O’Neill More at: jobs.newscientist.com This article was written and edited independently by New Scientist

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LETTERS EDITOR’S PICK

We worked out petrol’s ‘gearing ratio’

From Ilkka Savolainen, Helsinki, Finland Chris Eve wonders how much more heat burning a kilogram of petrol generates through the greenhouse effect than it does through the energy of combustion (Letters, 23 March). He calls this a “gearing ratio”, the name for the proportion of debt to capital used

in finance. With colleagues, I estimated this, though we called it the relative radiative forcing commitment (RRFC). This describes the ratio of the energy absorbed into the world’s atmosphere and surface to the pulse of fuel energy. Our computations started with models of the climate effects of carbon dioxide, methane and nitrous oxide. We found that the RRFC is a ratio of about 150 if we integrate these climate forcings over 100 years. Other emissions from combustion, such as black carbon, have some effect too. And the real global impact is roughly doubled because warming increases the amount of water vapour in Earth’s atmosphere. We concluded that the RRFC for diesel fuel is of the order of 300. That for petrol will be approximately the same.

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that comprise them, but it is the The goldilocks planet and how evolution works survival and reproduction of the From J. David Archibald, San Diego, California, US Bob Holmes discusses the idea of Earth as a superorganism featuring selection by persistence (23 March, p 34). This is intriguing and quite convincing. We should, however, make clear what we know about the actual process of evolution: namely, that the processes of natural selection, drift and other drivers of evolution operate at and below the level of an organism. Organisms survive and may reproduce. With perhaps a few exceptions, the results we see at higher levels such as populations are manifestations from these lower levels. Certainly, properties emerge at these higher levels that may determine the fates of populations and the organisms

organism that ultimately matters. Without this, these higher levels of organisation wouldn’t exist. From Malcolm Hunter, Leicester, UK I see that some critics of the idea that evolution by persistence could explain why our planet has been able to maintain relatively stable environmental conditions argue that spontaneous selfregulation can arise easily only in simple systems, and that it would be less likely to evolve the more complex a system becomes. But the more complex a system becomes, the more feedbacks there will be, both positive and negative. Positive feedbacks are destabilising, but extra negative feedbacks should mean that a system is unlikely to deviate far before a compensating negative

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“They’ll be saying this about Earth in a few decades” Lesley Wise expands on the news that Venus may have had a climate suitable for life billions of years ago (6 April, p 10)

feedback kicks in. Since the advent of life will massively increase a planetary system’s complexity, once it gets a foothold it is likely to limit environmental fluctuation. It will also tend to keep fluctuations within limits that are compatible with its own persistence. From Bernard Harper, Liverpool, UK James Lovelock’s Gaia theory has always made sense to me. The concept of selection by persistence seems entirely logical too. But a fundamental rule predating individual selection seems to be missing. Any randomly emerging biological chemistry cannot be selected for if it makes its immediate environment toxic to itself. Untold chemical trials and errors could happen until one arises that doesn’t randomly

poison itself through its own biology. Harmony will dominate because instability is lethal.

More challenges to adopting electric cars From Sam Edge, Ringwood, Hampshire, UK Jason Barlow applauds electric cars for personal transport entering the mainstream (23 March, p 24). Of course, getting rid of fossil-fuel-powered vehicles is a step in the right direction. But even if electrically powered, a car conveying one person to and from work five days a week is hugely inefficient. Our road networks cost a fortune to maintain and enlarge in both financial and environmental terms, purely to support this ever-expanding daily migration. Cars degrade the environment with noise, tyre wear, lubricants,

construction, disposal and maintenance, regardless of the energy source used. Until the semi-mythical autonomous car arrives, time spent commuting is wasted. Electrify them by all means, but please make the majority of non-freight vehicles on the roads be buses and allow employees to work from home where possible. From Dan Robinson, St Albans, Hertfordshire, UK Barlow asks what would make people switch to a pure electric car. I would switch when they are as practical and affordable as standard vehicles. A serious impediment is charging the batteries, but not because of the “range anxiety” that Barlow mentions. Like many people in the UK, I have to park my car on the street, and charging at home is impossible for me. The closest

charging point that I know of is at a supermarket more than a kilometre away. I wouldn’t leave a car there to charge overnight.

Fog in Channel, humour reinstated for a bit From Cozette Griffin-Kremer, Rambouillet, France I nominate Richard Webb for a prize for bringing science to the rescue of humans beset by political imbroglios (9 March, p 30). His account of “the original Brexit” offers proof that humour survives in the UK and is perhaps the most effective defence, at least of our equilibrium. From Gordon Cummings, Linton, Cambridgeshire, UK Webb mentions the headline “Fog in Channel: Continent Cut Off”. It isn’t just apocryphal, but one of the great misquotations. >

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LETTERS “Fog in Channel: Continent Isolated” appeared in a cartoon by Russell Brockbank in Round the Bend with Brockbank in 1948.

Do not be LED astray by coloured indicator lights From Graham Cox, Hothfield, Kent, UK John van Someren asks for the match of colour and function in indicator lights to be standardised (Letters, 9 March). On behalf of the many millions who are red-green colour blind, could we please never use red and green LEDs for off and on. From Bernard Cooke, Bristol, UK I would suggest getting rid of indicator lights. What is the point of wasting energy on an indicator to tell you that the TV is on?

What is new about this form of old plywood? From David Pengilley, Henley-on-Thames, UK Your article about the potential of wood makes much of building with cross-laminated timber or

CLT (16 March, p 33). Plywood has been around for many years – Samuel Bentham applied for patents in 1797. It has been used in furniture, buildings, cars, aircraft, spoons and much else. The nominal distinction is that plywood is glued from crosslaminated sheets of wood peeled from a log, while CLT is assembled from sawn sheets. But Bentham’s plywood was sawn. The editor writes: Q No one, that we can find, has built an entire medium-rise apartment block or a skyscraper from plywood as now defined.

The periodic table is an index to knowledge From Malcolm Shute, La Tour d’Aigues, France Your article on attempts to improve the layout of the periodic table was interesting (2 March, p 36). But I am not holding my breath for anything to come of it, any more than I was after your previous articles on this (12 July 2014, p 38, and 12 February 1994, p 36). Nice as it might be to

attempt to summarise everything that is known on a single poster, attempting to be all things to all people ends up being less useful. The beauty of the traditional arrangement of the periodic table, ordered by the number of protons in the nucleus, is that it provides a simple index in which you can easily find the desired entry and can then look up material from reference sources based on the information in it.

We need to teach uncertainty to all From Bryn Glover, Kirkby Malzeard, North Yorkshire, UK Wendy Glauser’s interview with Timothy Caulfield about the misinformation landscape was engaging (9 March, p 42). May I suggest that the root cause of the misunderstandings that fertilise this is that science education in general doesn’t tackle the difference between determinism and probabilism until much too late in any individual’s career. School exams deal only in certainties. The concept of uncertainty is often not broached

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until you study a science at university – an experience enjoyed by a small minority of the population. Thus asbestos producers were able to sweep aside concerns that first arose in the late 1930s. Tobacco companies asserted as late as the 1990s that there is “no proof” that smoking causes cancer. And just last month the UK’s prime minister felt able to claim that there was no link between police numbers and knife crime. A major part of the problem is that some wretched popular papers, their editors and their owners with private agendas delight in headlines about dithering scientists – and demand certainty. But science can offer only the best explanations that fit the evidence. Perhaps those who make television programmes about interesting aspects of the natural world could be persuaded to look at the need to explain uncertainty and to disabuse people and politicians alike of the notion that it is possible to always speak in the certain language of 2+2=4.

For the record Q A sweeter cube: mathematician Louis Mordell’s question is whether each integer can be expressed as the sum of the cubes of three integers (23 March, p 16). Q Looking for alignment of black holes’ spins is one way to find out what brings them together; there may be others (30 March, p 13). Q The trial of manipulation of cell surface sugars to help treat cancer is being run by a company called Phytoquest (30 March, p 34).

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 | 13 April 2019

QUICK CROSSWORD No29 Set by Richard Smyth

Tell us what you think at [email protected] ACROSS

1 Space station launched by the US in 1973 (6) 5 Soil or sediment, eroded and deposited (8) 9 Detection mechanism used in EPR spectroscopy (4,4) 10 Iron sulphide, FeS2 (6) 11 Italian-born author of Atoms in the Family (5,5) 12 Mineral aggregate; not paper or scissors (4) 13 μ+ (8) 16 Basalt-like 12 Across (6) 17 Flowering plant in the iris family (6)

19 Dugong or manatee (8) 21 The Seed Herbarium Image Project, or the Separator for Heavy Ion reaction Products? (4) 22 Term for an automobile feature also called a “telltale” (5,5) 25 In physics, a fundamental, one-dimensional object (6) 26 H, He or N, for example, as opposed to Sn, Au or Hg (8) 27 “There is ___ in this view of life” – Charles Darwin, 1859 (8) 28 Maxima or minima; boundaries (6)

DOWN

2 3 4 5 6

(5) Relating to Earth’s moon (5) Avian infection such as H5N1 (4,3) Acetylsalicylic acid (7) Pewit; green plover; Vanellus vanellus (7) 7 US astronomer (1928–2016) whose work provided evidence for dark matter (4,5) 8 Nettle rash (9)

14 Polaris (5,4) 15 2010 sci-fi film starring Leonardo DiCaprio (9) 18 Beach material (7) 19 B.F. ___ (1904–90), US behaviourist (7) 20 Vitamin A1 (7) 23 Section of the human small intestine (5) 24 Four-chambered organ (5)

THE UNIVERSAL UNITS OF THE MIND HOW A SI MPL E DATA M OD ULE UN DER LI ES A LL O UR TH OU GH TS A ND PERC EPTI O NS

Answers to Cryptic crossword No4 ACROSS: 7 SOCIAL NETWORK, 8 WORKOUTS, 9 APEX, 10 HALOGEN, 12 ESTER, 14 ENEMA, 16 EXAMINE, 19 ASPS, 20 PEDANTRY, 22 MAGIC MUSHROOM. DOWN: 1 POLO, 2 GINKGO, 3 ALBUMEN, 4 YEAST, 5 SWEATS, 6 TREE FERN, 11 AMNESIAC, 13 OXIDISE, 15 MOSAIC, 17 MANURE, 18 SPAMS, 21 ROOT.

MICHAEL JESSOP AND TERRY HILL

Answers and the next cryptic crossword in the 27 April issue

13 April 2019 | NewScientist | 55

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mosquitoes, the transmitters of dengue fever, Zika and chikungunya. While the song was being played, mosquitoes made fewer attacks on a test subject – a restrained hamster – and were less inclined to mate. The Skrillex track was chosen for its mix of high and low frequencies, but with no other songs tested, it is impossible to conclude whether mosquitoes have a general aversion to human music, or if the screeching synth and bass wobbles of dubstep just isn’t their jam. Perhaps they prefer jungle?

DEVOTED pope-watchers may have noticed a recent brouhaha swirling around His Holiness, owing to the pontiff’s reluctance to let worshippers kiss the papal ring. In video that rewards repeat viewing, the pope can be seen beckoning the faithful nearer with an encouraging smile before papally yoinking his papal hand out of the way so fast that some of the more enthusiastic congregants nearly take a papal tumble. The Bishop of Rome’s excuse for breaking with tradition is, apparently, an abundance of concern for hygiene. It seems that the papal signet ring, a Petrine Petri dish of divine proportions, risks turning into something of a holy weapon. Thank the lord it remains in the right hands.

THE times, they are a-changin’, but they will stop a-changin’ in the European Union from 2021, after the European Parliament voted to abolish daylight saving time.

Under existing rules, all member states are required to put their clocks forward an hour in March and back again in October. The European Commission moved to call time on the ritual after a public consultation showing that 84 per cent of respondents want to scrap it. “Member states should themselves decide whether their citizens live in summer or winter time,” said commission president Jean-Claude Juncker. As for the UK, its future membership of the EU is still uncertain at the time of writing, but our sources tell us permanent winter is a pretty likely outcome. AT LAST, we have a new weapon in the war on mosquitoes. Scientists in Malaysia have discovered that electronic music, specifically the Skrillex masterpiece Scary Monsters and Nice Sprites, has a disruptive effect on the behaviour of Aedes

Dave File’s packet of prochlorperazine tablets advises contacting a doctor when noticing any of a range of side effects including sudden death. “It may be rather difficult to comply!” he writes 56 | NewScientist | 13 April 2019

KEEPING up with the news often leaves Feedback in need of a lie-down. Luckily, the perfect opportunity has arisen to earn money in a horizontal position. NASA and the European Space Agency are offering €16,500 to 12 men and 12 women willing to stay in bed for 60 days. Not just any bed – one tilted 6 degrees so body fluids will be redistributed towards the head, mimicking the effect of microgravity. It is a tempting offer, but perhaps we need something stronger. Any researchers looking to study the effects of a year spent in the fetal position, get in touch.

weights of dogs, and its motor was so powerful that for “anything smaller than a Shih Tzu it had a propensity not so much to take the dog for a walk as to give it an impromptu flying lesson”.

THE sea can be cruel. It can be fickle. And sometimes, for no discernible reason, it can bombard your coastline with landline telephones shaped like the cartoon character Garfield the cat. This has been the strange plight of the people of Brittany for nigh on 30 years. These egregiously repulsive phones – whose eyes, so Sky News informs us, open when the receiver is lifted – were until recently of unknown origin. Speculation that they had been deliberately cast into the sea by some poor soul trapped on a desert-island-cum-Garfieldshaped-phone-factory doesn’t seem to have been rigorously pursued.

“AMERICAN teenagers take top spot in the global lying league”, reads a headline in The Times, reporting on a study investigating the deception skills of students in several Englishspeaking countries. Youths from the US – particularly male ones – were more likely than those in other countries to make up an answer when asked to explain non-existent mathematical concepts, such as “proper numbers”, “subjunctive scaling” and “declarative fractions”. No doubt the blagging abilities of US teenagers is not to be sniffed at, but for a journalist to declare them the world’s biggest liars does seem a tad hypocritical – especially for a story published on 1 April. The same jocular issue of The Times reported that readers could buy a drone that walks their dog for them. According to the article, the device struggled to adjust for the different

Instead, it fell to a local antilitter group to track the source down, eventually discovering an abandoned shipping container that had been leaking the plastic monstrosities into the sea. Distinctive flotsam can, of course, have genuine scientific merit, allowing us to track ocean currents and the movements of maritime life. But in this case, the insight it gives us into life in the 1980s is one we could do without.

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.

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THE LAST WORD Toe uncurling A friend recently passed on a tip for treating cramp. He said I should cup my hands over my nose and mouth and inhale my exhaled breath. It seems to work quite quickly for cramp in my toes. Is that a coincidence or placebo, or is there a rational explanation? Is it likely to work on more than my toes if necessary?

Q There is a plausible reason why this may help, although it assumes there was some hyperventilation – which results in low carbon dioxide levels in the blood – at the time of the cramps.

“Rebreathing exhaled air may help with cramp by increasing carbon dioxide levels in the blood”

As a respiratory physiotherapist, I have been called into hospital emergency departments more than once to treat patients who present as if they are having an epileptic fit when their symptoms are in fact due to a severe case of acute hypocapnia, or low carbon dioxide. Rachel Garrod Marbella, Spain Q Although rebreathing exhaled air – for example in and out of a paper bag – can increase the level of CO2 in the blood, breathing into cupped hands would be ineffective. To treat cramp, I recommend stretching the toes in the opposite direction to the cramp and keeping the feet raised. John Davies Lancaster, UK

Exhaled breath contains more carbon dioxide than ordinary air. Essentially, the act of breathing into cupped hands raises blood CO2 as you rebreathe this exhaled air. Although CO2 is a waste product of metabolism, it is also essential and controls a number of aspects of human physiology. For instance, it is needed for the normal dilation and relaxation of airways and blood vessels. When CO2 levels are low, these constrict, which can lead to symptoms such as wheezing and tingling in the hands and fingers. More pertinent to the question is the role CO2 plays in muscle activity. Low levels can cause muscle spasms and twitches.

Q Cramp can be caused by low levels of available calcium in the blood. Rebreathing exhaled air leads to a tiny rise in blood carbon dioxide, which makes the blood slightly more acidic. This increases the proportion of blood calcium – which is often bound to negatively charged sites on albumin proteins – in its free, ionised form. Cramps in fingers and toes will then rapidly improve. The questioner might have a chronically low level of calcium in the blood, which is most often caused by low vitamin D. Calcium and vitamin D supplementation would then stop the symptoms from happening so often. Theo Fenton London, UK

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

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Q Attempting to capture a gas in cupped hands is a pretty futile pursuit. But trying to do so may unconsciously alter the breathing, resulting in physiological change to the blood. The placebo effect might also be involved. Placebos have been shown to positively affect pulse, blood pressure, anxiety, pain perception and fatigue. They shouldn’t be dismissed just because we don’t yet know exactly how they work. David Muir Edinburgh, UK

Fuzzy thinking (continued) What is the function of the fuzz on the skin of a peach? And is a nectarine a bald peach or a peach a fuzzy nectarine?

Q The fuzz is there to protect the peach, which it does in various ways. It slows water loss by evaporation and can trap moisture, forming a protective layer over the fruit’s surface. The fuzz also affects the electric charge of the fruit surface, preventing substances from sticking to the peach’s skin. And it acts as a defence mechanism against certain insects, even preventing them from laying eggs. To answer the second part of the question, I would say that the nectarine is a bald peach. Genetically, the fruits are virtually identical, differing only in the peach having a

dominant gene that gives it fuzzy skin, while the nectarine has a recessive gene that results in smooth skin. Mark Ruth Nairobi, Kenya

This week’s questions CURRENT AFFAIRS

Discussions of the weather patterns over the UK and Ireland often used to mention the importance of the Gulf Stream ocean current. Today we hear much about the role of the jet stream high above the ground, but nothing about the Gulf Stream. Why is this? Jeff Blyth Brighton, UK GETTING AHEAD

My fringe seems to grow faster than the rest of my hair. Is this just because I notice it more or does hair grow at different rates on different parts of the head? Pamela Manfield The Narth, Monmouthshire, UK SPEED LIMITS

The most powerful cars intended for road use tend to have a top speed that ranges between 300 and 350 kilometres per hour. Is this due to some physical limitation or just practicality of design because you will never be able to reach these speeds let alone go faster on public roads? Sandy David Everdon, Northamptonshire, UK