March 30–April 5, 2019 New Scientist

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NO PLACE LIKE HOME

Exoplanets aren’t looking very friendly for life

CSI BOTANY

Meet the plant expert who solves murders

GIANT T. REX

Dinosaurs were even bigger than we thought WEEKLY March 30–April 5, 2019

THE TRIBE THAT REWROTE HISTORY DNA reveals the untold story of the ultimate Stone Age conquerors

ARE BLACK HOLES REAL?

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And four other questions gravitational waves will answer

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PLUS BILLION-VOLT THUNDERSTORM / SUN BEARS PULL FACES / YOUR GUIDE TO SPACE JUNK / THE HUNT FOR WATER ON MARS Science and technology news www.newscientist.com US jobs in science

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WHAT IF TIME STARTED FLOWING BACKWARDS?

WHAT IF THE RUSSIANS GOT TO THE MOON

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WHAT IF DINOSAURS STILL RULED THE EARTH? AVAILABLE NOW newscientist.com/books

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CONTENTS

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News Meet the heaviest T. rex ever found 7

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14 No place like home Exoplanets aren’t looking very friendly for life 38 CSI botany Meet the plant expert who solves murders 7

29 The tribe that rewrote history DNA reveals the untold story of the ultimate Stone Age conquerors 13 Are black holes real? And four other questions gravitational waves will answer

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Plus Billion-volt thunderstorm (18). Sun bears pull faces (18). Your guide to space junk (26). The hunt for water on Mars (6)

Our most pressing space challenge is to clean up orbit. Healthcare technology must be shown to work

News 4

THIS WEEK Thousands of vulnerabilities found on UK government websites. Boeing 737 glitch. British pollinators in crisis

6

NEWS & TECHNOLOGY AIs take on animals. Hunting water on Mars. Arctic warming worsens city smog. World’s largest T. rex fossil. Space rock mysteries revealed. Can genetic predictions improve healthcare? Google gets into video games. LIGO returns to hunt black holes. Pollution may reduce sperm quality. No life-friendly exoplanets. Child abuse brain link to depression.

Giant T. rex Dinosaurs were even bigger than we thought

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17 IN BRIEF Exploding star shoots through space. Robot swarms. Skin pigment turned into electrical wires. Anaesthetic may help PTSD

Analysis 20 INSIGHT UK’s online pornography block could be a privacy nightmare 22 COMMENT Genetic studies are too white. Media must do more to prevent suicides 23 ANALYSIS We need to stop travelling to cut climate emissions

Features 26 Your guide to space junk Cleaning up the skies overhead will be crucial for future launches 29 History of violence The devastating conquest written in ancient DNA 34 Life’s other code Deciphering the sugars on our cells could lead to a whole new type of medicine 38 CSI botany Jane Bock is a crime-fighting plant scientist

Culture 42 The inventor HBO’s new documentary explores the rise and fall of medical company Theranos PLUS: This week’s cultural picks 44 “The body is a spaceship” Artist Antony Gormley takes us skiing on the moon

Regulars 24 APERTURE Idai’s trail of destruction 52 LETTERS A significant source of earned dogmatism 55 CRYPTIC CROSSWORD 56 FEEDBACK Unusual solution to knife crime 57 THE LAST WORD Many ridges to cross

30 March 2019 | NewScientist | 1

INSTANT EXPERT: MYSTERIES OF THE MIND 11 May 2019 The British Library, London

You’re in possession of one of the most complex and incredible objects in the known universe: the human brain. How does a 1.4 kilogram tangle of nerve cells allow you to sense, understand and change the world? Discover why this is the most exciting time in the history of brain science with six experts working at the forefront of neuroscience, genetics and psychiatry. TOPICS COVERED WILL INCLUDE: Intelligence Consciousness Memory The mind-body connection The male-female brain

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Earth’s junkyard Our most pressing space challenge is to clean up orbit WHEN the Soviet probe Sputnik 1 started circling Earth on 4 October 1957, it was the only artificial satellite our planet had. That special status didn’t last long. There are now 20,000 identifiable objects in orbit around Earth, and many tens of millions that are too small to track. From flecks of paint to bits of old rocket and debris from accidental collisions, the skies over our heads are turning into a massive, floating junkyard. The situation has more than aesthetic drawbacks. Telescopes, space stations and thousands of communications satellites have to navigate this minefield every day,

travelling at speeds that would make even the tiniest collision disastrous. Left unchecked, the situation could jeopardise the future of space travel, with humans trapped in a cage of their own devising. Cleaning up our act will be no easy task. Nearly 400 objects were sent into orbit in 2018, and even more are scheduled for launch in the year ahead. On longer timescales, Elon Musk’s SpaceX has recently been given the go-ahead to put 12,000 satellites into orbit to provide the world with cheap internet. Other companies have similarly lofty ambitions.

With fresh rubbish being thrown on the heap all the time, responsible orbit management will involve finding ways to safely get shot of it all. A number of recent experiments – using everything from harpoons to nets by way of grippers modelled on sticky gecko feet – have had promising results (see page 26). However, some of these risk leaving behind more debris than they remove. Sixty years ago, the most pressing challenge in space technology was how to get more objects into orbit. Today, the top priority is getting them back down again. ■

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HEALTH minister Matt Hancock wants to transform the UK’s National Health Service into a cutting-edge healthcare machine, and his current obsession is using genetic tests to assess people’s risks of developing a range of diseases (see page 10). His own test showed an elevated risk of prostate cancer, he said – although experts pointed out

that it was pretty ordinary. It isn’t the first time Hancock has been distracted by something shiny, new and of uncertain value. The politician is a keen supporter of Babylon, which says its artificial intelligence can provide health advice on a par with human doctors. A review published in The Lancet says there is no convincing evidence that this is the case, and

the AI might actually be far worse. That said, Hancock doesn’t like all technology. He has repeatedly railed against children’s use of smartphones and called for official limits on screen time, despite a lack of clear evidence to suggest such devices are harmful. We all want healthcare providers to make use of modern technology when appropriate. But would it be too much to ask that the technology first be shown to work as advertised? ■ 30 March 2019 | NewScientist | 3

THIS WEEK

VCG/VCG VIA GETTY

Energy emissions rise GLOBAL carbon emissions from energy use climbed to a record high last year, as demand for energy grew at its fastest pace this decade. The International Energy Agency (IEA) said this week that emissions from energy use in 2018 rose by 1.7 per cent to a high of 33 gigatonnes. The increase is equivalent to the carbon released from all air travel doubling in a single year. This is the first official confirmation that energy-related emissions have risen two years in a row. It now seems that a plateau between 2014 and 2016 was a blip. “One could take a negative stance and say we’re doing everything wrong. I think it’s not as bad as the absolute number suggests. It could have been higher,” says Laura Cozzi, the IEA’s chief energy modeller.

Overall, the world’s appetite for energy was up 2.3 per cent, the biggest rise this decade. But switching from coal to gas power stations, which emit less carbon, helped damp down emissions growth to some extent, while nuclear power also had a good year, as new plants came online in China. And there was strong growth in renewable energy sources, which met 45 per cent of the increase in electricity generation in 2018. But the speed of change isn’t enough, says Cozzi. “We are putting the accent on the right policies, but they are not going strongly enough.” Glen Peters at the Centre for International Climate Research in Norway estimates that, based on economic growth predictions, total carbon emissions will rise again in 2019 by around 1.5 per cent.

First all-women spacewalk axed

MORE details have emerged about the two recent Boeing 737 Max 8

A THIRD of wild bee and hoverfly species are in decline across Great

down 38 per cent. By contrast, the common carder bee (below right) increased its range by 82 per cent. The assessment found that the key group of 22 wild bees and hoverflies for crop pollination had been doing

jet crashes. Both planes lacked two optional safety upgrades that could

Britain, raising concerns about decreasing biodiversity and the

relatively well. Overall, 11 per cent of the species studied increased their

Christina Koch and Anne McClain were scheduled to perform repairs outside

have warned the pilots of problems contributing to the crashes, The New

potential loss of pollinators. An analysis of 700,000 naturalist

range between 1980 and 2013 (Nature Communications, DOI:

the International Space Station on 29 March. Now Nick Hague will replace

York Times reported last week. The upgrades were linked to the

records going back to 1980 has found that about 33 per cent of 353 species

10.1038/s41467-019-08974-9). That is no reason for complacency

McClain, as there wasn’t time to put together a spacesuit that fits her.

Max 8’s Maneuvering Characteristics Augmentation System (MCAS), which

studied had declined in the extent of their range across the island. The

though, says Gary Powney at the UK Centre for Ecology and Hydrology.

Spacesuits are modular, with the torso, legs and arms all sized

was introduced to help avoid the plane pointing too far upwards and entering a mid-air stall. A report on the Lion Air crash, the first of the two crashes, suggested pilots had to repeatedly fight against MCAS as the plane pitched its nose into a dive 26 times. A part recovered from the Ethiopian Airlines flight, the second crash, hints MCAS may also have been involved. Additionally, the original safety analysis that Boeing delivered to the national regulator to certify the plane was safe to fly had several crucial flaws, according to an investigation by The Seattle Times. Official reports on the Ethiopian Airlines crash won’t be released for several months.

grey-banded mining bee (pictured below left) is among the losers,

“It’s a risky pollination strategy to rely on just 22 species.”

separately and then fitted together for each astronaut. According to NASA spokesperson Stephanie Schierholz, McClain trained on Earth using both medium and large-sized torsos. After a spacewalk on 22 March wearing a large-sized torso, she realised that the medium one was a better fit. This may partially be due to physical changes that happen in space. McClain tweeted earlier this month that she had gained 5 centimetres in height in orbit. It takes time to fit together and test a full spacesuit, so only one with a medium torso will be available by 29 March. Rather than delay, NASA switched out one of the astronauts.

4 | NewScientist | 30 March 2019

LEFT: MIKE EDWARDS; RIGHT: LUCY HULMES

Crashed jets lacked Tough times for safety upgrades Britain’s insects

THE first all-women spacewalk has been cancelled. NASA astronauts

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

Security flaws in government sites Hundreds of official UK websites found to have vulnerabilities. Chris Stokel-Walker reports

PLACEIT.NET

MORE than 500 UK government websites have serious security vulnerabilities, putting them at risk of being hacked, according to an investigation by a team of security researchers. Of the 3220 domain names registered under the .gov.uk domain ending, 524 have unpatched vulnerabilities. The sites encompass everything from central government departments to local and district councils. In total, the 524 insecure websites, including the National Archives, the Scottish prosecution service and the Health and Safety Executive, have about 7200 vulnerabilities between them. A team of security researchers working for IT companies in the private sector scanned all public-facing government domain names and looked at the servers hosting each of the websites. They found a hotchpotch of security issues, which they described as “severely unsafe”. Because many government services are increasingly delivered digitally, there is often little choice but to use these systems. longer than they should. This HMRC, the UK’s tax collector, was means that if an attacker steals not flagged as having any issues. someone’s cookie, which is a The vulnerable domains each relatively easy task, they can had at least one unresolved access their account. problem from the Common This vulnerability was posted Vulnerabilities and Exposures on the CVE system in late January, (CVE) system, a list of publicly but is still found 128 times across known software issues. The different .gov.uk domains. Some system rates vulnerabilities on of the .gov.uk vulnerabilities a scale of 1 to 10, with 10 being the have been known for more than most dangerous, based on how a decade. EU data protection rules easy they are to exploit and the say vulnerabilities should be consequences of such an attack. patched in a timely manner. The most commonly found The analysis shows there are vulnerability across the significant weaknesses in the UK government websites, CVE-2018“Of the 3220 domain names 17199, is rated a 7.5. Web servers with this vulnerability sometimes with the .gov.uk ending, 524 have unpatched store cookies, which are used to vulnerabilities” verify who is accessing a website,

The Health and Safety Executive website is flagged as having an issue

government’s IT infrastructure, says Daniel Abbott, a security engineer at IT firm Node4, and part of the team. Many machines are using very old versions of software. “This demonstrates a lack of reasonable care and attention,” he says. The domain with the most CVE issues – 266 vulnerabilities – is run by a parish council. However, some central government services also have large numbers of unpatched holes. The former website of the Criminal Records Bureau, crb.gov.uk, which now forwards to the government’s Disclosure and Barring

Service (DBS), an organisation that handles millions of criminal record checks for employers, has 133 vulnerabilities. Many issues seem related to the fact that the website appears to use versions of server software that are nine years out of date. If the crb.gov.uk host is compromised, an attacker could divert users, such as those seeking a criminal-record check to give to employers, to a third-party website and masquerade as the DBS, accessing personal details, potentially including past criminal convictions. “Poorly managed services can allow hackers to gain back doors into secure government networks,” says James Sawyer, part of the team. That allows hackers to then launch attacks. Unpatched vulnerabilities made the WannaCry attack in 2017 possible, in which ransomware hit more than 300,000 computers worldwide, including thousands used by the NHS. Microsoft had already released a fix for the vulnerability exploited by WannaCry, but it had yet to be installed on many computers. “It seems that there is a problem,” says Robert Baptiste at French security company fsecurity, who wasn’t involved in the investigation. But until there is evidence of these vulnerabilities being exploited, it is difficult to say how much of an issue they are, he says. The UK government told New Scientist it takes cybersecurity seriously and will investigate thoroughly. It added that departments routinely test their own sites for vulnerabilities and fix any that are found. “The public should remain confident that all details held on gov.uk are safe and secure,” said the Cabinet Office. ■ 30 March 2019 | NewScientist | 5

NEWS & TECHNOLOGY

AI vs animals in a battle of smarts Although it won’t be in the competition, the A-not-B task is one such test of this ability. In the task, an animal is repeatedly presented with two cups, A and B. For the first few iterations, cup A always contains a piece of food. However, once the animal is trained to understand this, the experimenter switches the food to cup B in plain sight. Some animals, such as dogs, continue

SOME artificial intelligences can perform tasks with superhuman ability, but just how clever are they overall? As smart as a honeybee? A Labrador? Or a chimp? A competition called the Animal-AI Olympics will pit AIs against tests normally used to study animal intelligence. From April, AIs will battle it out in a virtual playground for a $10,000 prize pool. All the tasks involve retrieving a piece of food, but the skills needed to succeed vary in complexity. This mimics real-life experiments used to measure animal intelligence. Entrants will complete tasks they haven’t seen before to eliminate the opportunity to swot up beforehand, says Matthew Crosby at the Leverhulme Centre for the Future of Intelligence, UK. The Animal-AI Olympics will test a range of cognitive skills, such as the ability to reason, navigate and learn from past experiences. “One key concept is object permanence, the understanding that objects continue to exist even when they’re out of sight,” says Crosby.

Magnetism aids search for Mars water NASA’s InSight lander is meant to be busy measuring seismic activity and underground heat flow on Mars. That isn’t going to plan, but it is using one of its less important sensors to make the very first measurements of the planet’s magnetic field from the surface, which may help us find water. Since InSight’s arrival on the Red Planet in November, its main 6 | NewScientist | 30 March 2019

Can AIs succeed at versions of tests that African grey parrots ace?

JUNIORS BILDARCHIV GMBH/ALAMY STOCK PHOTO

Donna Lu

to persevere with cup A, but others, such as macaques, instantly switch to cup B. The variety of tasks in the competition will challenge one key limitation of many AIs: once they learn something, it is very difficult for them to adapt that knowledge to a similar but different situation. For example, one AI can outperform humans at the video game StarCraft and another beats us at the board game Go, but they are both useless at most other tasks unless completely retrained.

instrument, a seismometer, hasn’t detected any Marsquakes. The lander’s heat probe is designed to burrow 3 metres below the surface before it starts gathering data, but it has hit a rock and become stuck. Enter the magnetometer, which isn’t even designed to study Mars directly. “It’s there to measure anything that might affect what the seismometer measures,” says InSight scientist Catherine Johnson. “But we’re using it for science anyway.” The first results were presented at the Lunar and Planetary Science Conference in Texas last week.

Unlike Earth, Mars lacks a global magnetic field, but it probably had one in the past, which led to magnetised rocks in its crust. Electric currents created by charged particles from the sun generate small magnetic fields in those rocks, which InSight’s magnetometer picks up. “We can use it to probe how much water is locked up in those rocks,” says Johnson. We have been unable to do this

“Unlike Earth, Mars lacks a global magnetic field, but it probably had one in the past”

A leader board will be provided during the competition, which runs until November. The big hurdle will be to build AIs with general intelligence: systems with common sense and the ability to do a wide range of tasks based on limited data, says Chris Summerfield at the University of Oxford. Many AI algorithms mimic certain functions in animal brains, such as the visual system in primates, he says. This is why image-recognition software, such as used by Google’s reverse image search, has been so successful. But AIs lack many other brain features that contribute to cognitive ability, including short-term memory or future planning. This may explain why AIs are good at specific tasks, but struggle to adapt to others. Testing AI systems in unfamiliar environments is an important step to creating AIs that can solve a wide range of problems beyond those they were initially designed for, says Crosby. “We expect this to be a hard challenge,” he says. “A perfect score will require a breakthrough in AI, well beyond current capabilities. However, even small successes will show that it is possible, not just to find useful patterns in data, but to extrapolate from these to an understanding of how the world works.” ■

before because orbiting spacecraft can only detect magnetic fields that make it all the way off the surface into space. That doesn’t tell us what is happening on the ground. Because of this, we thought the small magnetic fields on the surface would be 10 times weaker than InSight found. As the lander’s magnetometer continues collecting data, we may learn how much water there is inside minerals underground and how strong Mars’s primordial magnetic field was. This could help us understand why the planet is now so different from Earth. Leah Crane ■

For daily news stories, visit newscientist.com/news

Polar warming may make smog pollution worse

conditions in the Arctic reduce temperature differences in the northern hemisphere. The result may be a weakening of high-speed winds that normally blow eastwards. Less pollution could then get dispersed, causing aerosols to build up in some areas. Big mountain ranges, including the Himalayas and central China’s Qingling peaks, may block air flow further. Zhao says his team’s work should enable governments to predict smog levels based on Arctic temperatures, “so they can come up with better mitigation plans”. But Tim Garrett at the University of Utah says the study only shows that Arctic warming and smogs are associated – it is unclear if one leads to the other. Meanwhile, Arctic sea ice probably reached its maximum extent for 2019 on 13 March. Initial measurements put this at 14.8 million square kilometres, the joint-seventh lowest figure in the past 40 years. Yvaine Ye ■

AMANDA KELLEY

MILDER conditions in the Arctic could be weakening winds in China and India, making winter smogs worse. Burning fossil fuels can result in severe clouds of pollution in many cities in Asia, including Beijing and Delhi. These smogs – aerosols of fine particles – are worse in winter, when more fuel is used for heating and weather patterns that can cause dirty air to linger tend to take hold. Chuanfeng Zhao at Beijing Normal University in China and his colleagues wondered if rising temperatures in the Arctic affect this. Going as far back as 1980, they compared the monthly average temperature of the Arctic with atmospheric aerosol levels of the northern hemisphere’s mid-latitude regions, where many industrialised cities are. They found that, when the Arctic had a particularly warm summer, aerosol concentrations in east Asia and north India tended to be higher than usual the following winter (Climate Dynamics, doi.org/c3tj). This could be because warmer

Scott Persons measures a toe bone from the heftiest ever land predator

Introducing Scotty: the world’s heaviest T. rex AS IF Tyrannosaurus rex wasn’t 8870 kilograms. To put it another scary enough, along comes Scotty. way, Scotty was a couple of adult This specimen, dug up in Canada, male lions heavier than Sue. turns out to be bulkier than any Scotty was actually discovered known T. rex, making Scotty the at about the same time as Sue, but heftiest land predator on record. because its bones were encased in The finding means we may have particularly hard rock, freeing underestimated how massive them took decades. predatory dinosaurs could grow. “It wasn’t until now that we’ve T. rex was one of the last nonbeen able to take a step back and bird dinosaurs to evolve, and has long been considered a contender “One mystery is why these for the largest of all the predatory creatures could grow to be so large when they had to dinosaur species. That case was hunt fast-moving prey” made even stronger following the discovery of Sue in South Dakota, a 90-per-cent-complete T. rex look at the specimen as a whole,” skeleton unearthed in 1990. says Persons. “There was an ‘oh This was described as the largest gosh’ moment, because the animal of its kind in the world specimen really is enormous.” Scotty has now stolen the title. Strictly speaking, it isn’t the “We’re talking about basically a longest or tallest T. rex found, 400-kilogram difference,” says but it is the heftiest. Persons and Scott Persons at the University of his colleagues used a few methods Alberta, Canada. According to his to work out how heavy Scotty team’s calculations, Sue weighed would have been, including using an impressive 8460 kilograms, the circumference of its thigh but Scotty tipped the scales at bones to calculate how much

weight the legs were capable of supporting (Anatomical Record, doi.org/c3tm). The researcher think they know why Scotty was so heavy. Its bones suggest it was an exceptionally old individual, probably in its early 30s. So T. rex might have reached its maximum body length and height earlier in adulthood, but then bulked up as it became older. The idea has big implications. Other members of this group of meat-eating dinosaurs, known as theropods, might have followed the same trend, bulking out only after many years. But given that life for these animals was pretty tough, few individuals will have reached that full potential, meaning fossils of the oldest and bulkiest theropods will be very rare. Many palaeontologists have been waiting a long time for a full description of Scotty, says Stephen Brusatte at the University of Edinburgh in the UK. “It is probably our best look yet at what one of the largest, oldest, most fully grown adults would have looked like.” That Scotty seems to be the heaviest T. rex ever found is a reminder that the numbers of samples of giant theropods are small, says Brusatte. “New discoveries can reveal even bigger or weirder individuals.” One mystery is why T. rex could grow to be so large. For other gigantic theropods, there are mitigating factors that might explain how they survived: for instance, living in water to support their body weight or hunting very slow-moving dinosaurs that weren’t difficult for a heavy predator to catch. But T. rex lived on land, hunting fast-moving dinosaurs. “So why do tyrannosaurs go down this road of gigantism? We don’t know the answer to that,” says Persons. Colin Barras ■ 30 March 2019 | NewScientist | 7

NEWS & TECHNOLOGY

Space rocks reveal surprises galore The lumps seen ejected from it range from a few centimetres to tens of centimetres in size. At least four appear to have ended up in orbit around Bennu, forming what are essentially miniature moons around the asteroid. “We have had spacecraft around other asteroids, and nothing like this was ever reported,” says Andrew Rivkin at Johns Hopkins University in Maryland. “The question is, why is this asteroid different?” One major distinction is that, unlike the other asteroids we have been to, Bennu is full of hydrated

Leah Crane

8 | NewScientist | 30 March 2019

Clockwise from top left: Bennu is bumpy, Ryugu is dry, while MU69 resulted from a slow collision

NASA/GODDARD/UNIVERSITY OF ARIZONA, JAXA, NASA/JHU-APL/SWRI

THREE missions have been gathering a treasure trove of data on the nature of space rocks in the solar system, making unexpected findings that may shed new light on how Earth formed. Earlier this year, NASA’s New Horizons probe flew by MU69, the most distant rock we have visited. This tiny world is made up of two lobes, and looks a bit like two pancakes stuck edge to edge. Results presented at the Lunar and Planetary Science Conference in Texas last week show that both lobes are covered in organic compounds that give them a red hue. Their surfaces also show signs of water ice and methanol, a compound of methane and oxygen. The shape of the final object, with both lobes in the same plane, suggests that they were separate rocks that orbited one another closely in a slow dance before merging. A lack of large cracks or rubble on MU69 suggests that when the two objects merged, they probably hit each other at just 2 or 3 metres per second. “If you take a brisk walk into a wall, you will find out what that [sort of collision] is like,” says team member Bill McKinnon at Washington University in Missouri. Elsewhere, NASA’s OSIRIS-REx spacecraft has spotted the nearEarth asteroid Bennu spewing out dust and rocks on 11 separate occasions in just a few weeks, which took us by surprise. For the most part, Bennu is as we predicted before OSIRIS-REx arrived in December: shaped like a spinning top and rotating once every 4.3 hours. It isn’t very dense and its surface is one of the darkest in the solar system.

minerals that have water locked Earth in 2023. Because Bennu into their molecular structure. is a relic from the age of planet So there is a chance it also has ice formation in the early solar under its rocky surface, in which system, material from it may help case heat from the sun could be us understand how planets like turning the ice into gas and Earth formed and where Earth got blowing rocks away, says Rivkin. its water and complex chemistry. Efforts to learn more about Finally, Japan’s Hayabusa 2 Bennu may be hampered by spacecraft has sent back its first another surprise: its surface is data on the near-Earth asteroid covered in large boulders, which Ryugu, revealing another could make it more difficult for surprise: it appears to have OSIRIS-REx to descend and grab virtually no water at all. a sample from it. The asteroid’s surface is Instead of smooth areas coated in dust, the surface has thousands “Asteroid Bennu has been spotted spewing out rocks, of small boulders and more than 200 that are in excess of 10 metres forming what are in effect miniature moons” across. We only expected one rock this big from images taken before the spacecraft orbited Bennu. extremely dark, reflecting less The mission was designed to than 2 per cent of the light that pick up samples from dusty hits it. Comparisons with regions, not rocky ones. The team meteorites we have collected on has found only a few areas that Earth – which were heated as they will work, but it is confident it will passed through our atmosphere – still be able to get a sample of dust. show the colours match. This OSIRIS-REx is set to return to suggests the asteroid was heated in the past, perhaps when it was chipped off from a larger object. That could also explain why there seems to be very little water on the asteroid. Given Ryugu probably formed in the water-rich asteroid belt, it is unlikely that it was dry from the start, says team member Seiji Sugita at the University of Tokyo. “Our preferred scenario is that the parent body acquired water and then subsequently re-expelled most of the water,” he says. Because Ryugu’s surface is so homogeneous, this indicates its parent body may have lost its water through heating from radioactive materials rather than being hit by other objects, as collisions wouldn’t affect the entire asteroid equally. Researchers have long thought that asteroids like Ryugu may have brought water and other essential ingredients for life to Earth in the distant past. If it turns out that many of them, like Ryugu, don’t have much water, we may have to think again and look for these things elsewhere. ■

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NEWS & TECHNOLOGY

Adam Vaughan

ANALYSING the genetic data of millions of people can help predict a person’s risk for common diseases and could allow the UK’s National Health Service to save lives and money, according to Genomics plc. The firm, which was spun out from the University of Oxford, announced on 20 March that it has produced “polygenic risk scores” for heart disease, breast cancer and 14 other diseases by examining more than 3 million people’s genetic data. Half a million genomes came from the UK Biobank, while the rest were from more than 200 other institutions. Such scores could help the NHS take preventative action and target scarce resources better, says the firm’s co-founder, Peter Donnelly. For example, women whose genes indicate they have a higher risk of breast cancer could be screened earlier than their 50th birthday, when checks usually start. The same day as Genomics plc’s announcement, the UK health minister Matt Hancock gave a speech on increasing the use of such techniques in the UK.

Google to launch video game service ANYONE will be able to play video games without the need for dedicated consoles or high-end computers with a service on the way from Google. Stadia will be a cloud gaming service, meaning that any heavyweight processing and graphics rendering will be performed at Google’s data centres. As a player moves around in a game, video of 10 | NewScientist | 30 March 2019

“We must get predictive testing into the NHS as soon as we possibly can,” he said. Genetic testing is already used in the NHS to look for diseases caused by a single gene, such as cystic fibrosis. But many common health problems involve multiple genes that each have a small effect, making it more difficult to screen for them. Polygenic risk scores compare a subset of genetic variants in someone’s genome with large analyses of genetic data to estimate how likely that person is to develop a particular condition. Anneke Lucassen at the University of Southampton, UK, thinks these risk scores could help identify high-risk groups and play a role in targeting screening for diseases. But she says it is unclear what people given such a score should do with the information. “We tend to assume that picking up something early makes it more treatable, but sometimes there is little evidence for that assumption and the downside of overdiagnosis is often ignored.” Other researchers are also sceptical about the technique’s accuracy. “For most diseases,

the gameplay will be streamed to their device. Providing the internet connection is good enough, this will happen seamlessly. The platform, which will launch later this year, will let users immediately play any game available on the service, without needing to buy it individually or download a copy. “Stadia offers instant access to play,” said Google’s Phil Harrison at the Game Developers Conference in San Francisco. Stadia can be used with existing USB controllers, but Google also unveiled a purpose-built one. This will

PKEVIN CURTIS/GETTY

Gene screening for disease risk

Genetic sequencing can help predict future health problems

the best polygenic risk scores do not perform well enough to be of practical use,” says Doug Speed at Aarhus University in Denmark. David Curtis at University College London shares that view. Polygenic risk scores may not be as useful as they seem, he says. Another problem is that there is no single, definitive polygenic risk score for any given disease. The scores that Genomics plc

connect via Wi-Fi to the game in the cloud and includes a button that allows people to share video of their gameplay to YouTube. The release of Stadia comes as the industry shifts towards cloud gaming. Competitors in this field include Microsoft’s Project xCloud, Sony’s PlayStation Now and Nvidia’s GeForce Now. One problem that cloud gaming

“Heavyweight processing and graphics rendering will be performed at Google’s data centres”

arrives at, for instance, may differ from those of another company, meaning the NHS would have to choose which one to use. On top of that, genetic research has largely focused on people of white European ancestry (see Comment, page 22). Polygenic risk scores are currently less accurate for anyone with non-white ancestry, as they are under-represented in the genetic databases the scores are derived from. “I think that’s a dealbreaker,” says Curtis. ■

platforms have faced is latency, a lag between a player pressing a button and an action occurring on screen. At launch, Stadia will aim to stream games in up to 4K resolution at 60 frames per second. A further, simultaneous, stream can be shared to YouTube, also at 4K. This will be increased to an 8K resolution later on. Stadia is likely to spark a rise in metrics-driven game design, says Tanya Krzywinska at Falmouth University, UK. “They will be able to gather huge amounts of data about when people are playing and what they’re playing,” she says. Donna Lu ■

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NEWS & TECHNOLOGY Air pollution may reduce sperm quality

What is inside a neutron star?

Are black holes even real?

sperm in mice that had been exposed to PM2.5 compared with those

Neutron stars are the city-sized remnants of massive stars, squeezed to densities greater than that inside the nucleus of an atom. We have felt the ripples from collisions between them once. More detections will let us better probe their innards.

A black hole’s whole shtick is that you can’t see it. The only ways we know they are out there are that we see gas, dust and stars

NUTSINEE KIJBUNCHOO/ANU/LIGO HANFORD

system – or mature black holes are somehow pushed together by interactions with other objects. Or maybe both. The only way to find out is to see whether the spins of merging behemoths are aligned.

Institute claimed that the first gravitational wave ever detected was echoing. That was a big surprise, because it would indicate the presence of a ring of high-energy particles around a black hole, known as a firewall. This would contradict Einstein’s theory of general relativity. LIGO’s third run should settle the matter.

DIRTY air in urban areas may be having an impact on human sperm. A study shows that mice exposed to tiny pollution particles have worse sperm quality and make less of it than mice that don’t breathe these particles in. Many health problems are linked to pollution emitted by petrol and diesel cars, including respiratory issues, cancer and stunted development in childhood. However, whether the smallest of these air pollutants, those less than 2.5 micrometres across known as PM2.5, could also contribute to increasing male infertility rates around the world is still unclear. Elaine Costa at the University of Sao Paulo in Brazil and her colleagues studied four groups of mice. The team exposed three of the groups to PM2.5 for different proportions of their lives. The fourth was exposed to filtered air. Costa’s team analysed sperm development when the mice became adults. There was a deterioration in the tubes in the testes that produce

LIGO returns to probe black holes Daniel Cossins

THE search for gravitational waves is back on, and this time we are expecting a deluge. The Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US made a huge splash in 2016, when it announced the detection of faint ripples in space-time produced by the collision of a pair of black holes. It has since spotted 10 more gravitational-wave events. Now, following upgrades, LIGO should see one a week when it starts up again on 1 April. “We’re making the transition from having a slow drip of events to opening the faucet,” says Luis Lehner at the Perimeter Institute for Theoretical Physics in Waterloo, Canada. “It’s going to be amazing.” Astrophysicists are hoping this torrent will give us answers to these five questions: How do black holes pair up?

We still don’t know what brings black holes together. Either the stars that collapse to create them start out in a pair – a binary

An extensive upgrade has made LIGO more sensitive than ever

“We’re making the transition from having a slow drip of events to opening the faucet”

Can we see inside a supernova?

Core-collapse supernovae are the universe’s most spectacular fireworks display – dramatic explosions of dying giant stars that give birth to neutron stars and black holes. So far, we know them only from the light they emit, but they should produce gravitational waves too. Glimpsing these waves should let us peer inside. Do black holes have a wall of fire?

In 2016, a team led by Niayesh Afshordi at the Perimeter

falling in, and we can detect gravitational waves from them. Then again, it is possible that at least some of the things we think are black holes are in fact exotic, hypothetical objects called boson stars. Their strange form prevents them collapsing to become a black hole, but they would distort space-time in much the same way. The only way to find out if boson stars are real is to search gravitational wave signals for a distinct frequency. ■

breathing filtered air. And the quality of sperm was worse in mice exposed to pollution before and after birth. Exposure to air pollution after birth seemed to have the biggest effect on sperm. DNA tests also showed changes in the activity of genes related to testicular cell function. “These findings provide more evidence that governments need to implement public policies to control air pollution in big cities,” said Costa in a press release. The work was presented at a conference of the Endocrine Society in New Orleans. More work is needed to understand any link between poor air quality and infertility in men, says Frank Kelly at King’s College London. While animal studies are useful in examining any underlying mechanisms, the results seen in mice don’t necessarily translate to the same effects in humans, he says. Adam Vaughan. ■ 30 March 2019 | NewScientist | 13

NEWS & TECHNOLOGY

Exoplanets for life in short supply the planet would be sterilised. Because one is based on temperature and the other on the strength of certain wavelengths of light, the habitable zone and the abiogenesis zone around any star don’t always overlap. Marcos Jusino-Maldonado and Abel Méndez at the University of

WE HAVE found more than 4000 planets orbiting distant stars, but it turns out that probably none of them have the right conditions for life to evolve, making Earth even more special than we thought. We normally consider a planet to be capable of hosting life if its surface is the right temperature for liquid water. This depends on how close it orbits its star – too far and any water will freeze, but too close and it will boil away. The area around each star where these water-friendly orbits lie is called the habitable zone. But just being technically habitable doesn’t mean that a world has the right conditions for life to arise. One of the leading explanations for life’s emergence on Earth is that ultraviolet light from the sun played a role. The idea is that UV light hitting simple molecules gave them enough energy to react and form the more complicated compounds required to make a living organism. In line with this idea, researchers last year introduced a concept called the abiogenesis zone: the area around a star where a planet could get enough UV light to start this prebiotic chemistry, but not so much that

Child abuse brain link to depression A STUDY of more than 100 people’s brains suggests that abuse during childhood is linked to changes in brain structure that may make depression more severe in later life. Nils Opel at the University of Münster, Germany, and his colleagues 14 | NewScientist | 30 March 2019

Kepler-452b is the only known exoplanet that might host life

NASA AMES/JPL-CALTECH/T. PYLE

Leah Crane

Puerto Rico at Arecibo applied the requirements for the abiogenesis zone to a list of known exoplanets in the habitable zone, of which we have found 49. Only eight worlds matched the criteria. “Even these eight are bad because they have a large radius, which means they might not be rocky,” says Jusino-Maldonado, who presented the work last week at the Lunar and Planetary Science Conference in Texas.

scanned the brains of 110 adults hospitalised for major depressive disorder. The team also asked about the severity of their depression and whether they had experienced neglect or emotional, sexual or physical abuse during childhood. Statistical analysis revealed that those who had experienced childhood abuse were more likely to have a smaller insular cortex, a brain region involved in emotional awareness. Over the following two years,

75 of the adults experienced another bout of depression. The team found that those who had both a history of childhood abuse and a smaller insular cortex were more likely to have a relapse (The Lancet Psychiatry, doi.org/c3r9). “This is pointing to a mechanism:

“Childhood trauma may lead to altered brain structures and these may lead to the recurrence of depression”

Bigger planets tend to accrete gas as they grow, becoming gas giants like Neptune or Jupiter instead of rocky worlds like Earth or Mars. Previous work has suggested that planets larger than 1.7 times Earth’s radius are likely to be gassy. “If the planet is too big, it’d be hard to think how life as we know it could evolve,” says Ramses Ramirez at the Tokyo Institute of Technology. Of the eight planets inside both zones, only one has a radius less than 1.7 times Earth’s: a planet called Kepler-452b, which orbits a sun-like star 1400 light years away. Its radius is 1.63 Earth radii, so it is right on the edge. That means that out of more than 4000 exoplanets, we may have found only one where life could evolve – or perhaps none, if Kepler-452b turns out to be a gas planet. The only two planets we know for sure to be rocky and in both the habitable and abiogenesis zones are Earth and Mars. As far as we can tell, Mars doesn’t have any life. This shows just how difficult it probably is for life to arise. “If our goal is to find life, we need to be finding a lot more exoplanets than we can see with the technology we have now,” says Ramirez. Plus, there is no guarantee that a planet where life could arise will actually have anything living on it. “It’s getting harder to find origins of life,” says Jusino-Maldonado. “It seems very unlikely.” ■

that childhood trauma leads to brain structure alterations, and these lead to recurrence of depression and worse outcomes,” says Opel. The findings suggest that people with depression who experienced abuse as children could need specialised treatment, he says. Brain changes can be reversible, says Opel, and the team is planning to test which types of therapies might work best for this group. Ruby Prosser Scully ■

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Postdoctoral Fellow - Cancer Biologist The Beckman Research Institute of City of Hope is looking for a talented Postdoctoral Fellow. This position will be running assays to characterize activity of molecules produce. Basic education, experience and skills required for consideration: z

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Additional Information Please note, this is one of three Postdoctoral Fellowships available in Dr. Williams’ lab. Other descriptions in Computational Biology and Display Methods may be found on our main vacancy page. City of Hope is committed to creating a diverse environment and is proud to be an equal opportunity HPSOR\HU$OOTXDOLƬHGDSSOLFDQWVZLOOUHFHLYH consideration for employment without regard to race, religion, color, national origin, sex, sexual orientation, gender identity, age, status as a protected veteran, or VWDWXVDVDTXDOLƬHGLQGLYLGXDOZLWKGLVDELOLW\

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46 | NewScientist | 30 March 2019

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NRC Research Associateship Programs

The National Academy of Sciences, Engineering, and Medicine offers postdoctoral and senior research awards on behalf of 23 U.S. federal research agencies and affiliated institutions with facilities at over 100 locations throughout the U.S. and abroad. We are actively seeking highly qualified candidates including recent doctoral recipients and senior researchers. Applications are accepted during 4 annual review cycles (with deadlines of February 1, May 1, August 1, November 1).

Interested candidates should apply online http://sites.nationalacademies.org/PGA/RAP/PGA_046398 Awardees have the opportunity to: • • • •

conduct independent research in an area compatible with the interests of the sponsoring laboratory devote full-time effort to research and publication access the excellent and often unique facilities of the federal research enterprise collaborate with leading scientists and engineers at the sponsoring laboratories

Benefits of an NRC Research Associateship award include: • • •

1 year award, renewable for up to 3 years Stipend ranging from $45,000 to $80,000, higher for senior researchers Health insurance, relocation benefits, and professional travel allowance

DESIRED SKILLS AND EXPERIENCE

Applicants should hold, or anticipate receiving, an earned doctorate in science or engineering. Degrees from universities abroad should be equivalent in training and research experience to a degree from a U.S. institution. Some awards are open to foreign nationals as well as to U.S. citizens and permanent residents.

ABOUT THE EMPLOYER

The National Academies of Sciences, Engineering, and Medicine’s Fellowships Office has conducted the NRC Research Associateship Programs in cooperation with sponsoring federal laboratories and other research organizations approved for participation since 1954. Through national competitions, the Fellowships Office recommends and makes NRC Research Associateship awards to outstanding postdoctoral and senior scientists and engineers for tenure as guest researchers at participating laboratories. A limited number of opportunities are available for support of graduate students in select fields.

30 March 2019 NewScientist | 47

2019

Innovation & Inclusion

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April 24, 2019 | Washington, DC ANDREW W. MELLON AUDITORIUM

Scientific Reviewers: Physical Sciences, Life Sciences & Psychology (Work-from-home) Cactus Communications is a leading provider of scientific communication services to more than 198,000 clients across 116 countries. We engage a team of highly skilled editors who are experts in various academic fields. Cactus Communications has consistently ranked among the top 20 on the global list of the Top 100 Companies for Telecommute Jobs (Forbes.com) since 2016. We are currently looking for researchers and editors who can provide detailed assessments on manuscripts (along the lines of journal peer reviews).

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This could be you: A NASA Postdoctoral Fellow investigates short gamma-ray bursts that could be from the same cosmic collision that created the gravitational waves that were detected by LIGO, the first-ever observation of gravitational waves.

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Fields of study include:

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Fermi GBM Observations of LIGO Gravitational Wave event published by V. Connaughton, USRA, E. Burns and A. Goldstein, NASA Postdoc, et al.

Image Credit: NASA/C. Henze

50 | NewScientist | 30 March 2019

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LETTERS EDITOR’S PICK

A significant source of earned dogmatism

From Allan Reese, Forston, Dorset, UK David Robson describes “earned dogmatism” as the tendency of a person to overestimate their expertise based on past training (23 February, p 30). I used to advise PhD candidates as a statistician, and was particularly aware of examiners from many

disciplines who claimed sweeping knowledge of statistical methods, apparently based on an introductory course in the subject taken a long time ago or on having analysed their own data for years. A particularly memorable example was a PhD student who was told after their oral “viva” examination that their thesis was sound but their statistics must be reworked using a different kind of method. The student accepted it was easier and quicker to comply than to challenge this verdict. The reworking changed no results. Scientific papers, refereed by experts in their field of science, get published with glaring statistical flaws. I have yet to find a journal editor who admits that the statistical treatment of data should probably be refereed by a competent statistician.

Pension divestment can combat climate change From Gabriel Carlyle, St Leonardson-Sea, East Sussex, UK Students in over 100 towns and cities in the UK took part in the global Youth Strike for Climate on 15 March, inspired by Greta Thunberg (16 March, p 7). Many may not be aware that their schools and sixth-form colleges may be funding businesses linked to climate change through their payments to pension schemes. Pension schemes run by local government are estimated to have £16 billion invested in oil, coal and gas companies. In East Sussex, a Freedom of Information Act request revealed that in excess of 40 local schools and colleges together contribute at least £9.8 million a year to the East Sussex Pension Fund, which has investments in fossil fuel firms.

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By taking action in schools to get pension schemes to support divestment from fossil fuel companies, students, parents, teachers and staff can help to break the hold that these firms currently have on economies and governments around the world, and make way for a transition to renewable energy.

How male and female brains may differ From Janita Cunnington, Point Lookout, Queensland, Australia Gina Rippon makes the points that men and women are more similar than they are different and that every person’s brain is unique (2 March, p 28). She concedes that the sexes differ statistically in preferences, behaviour and abilities. How can these slight but observable differences be

“I generally recommend you breathe in every once in a while” Sabine Hossenfelder drily concurs with a finding that breathing in before doing something may make you better at it (16 March, p 8)

explained? Rippon entertains only two possibilities – genotype and the influence of stereotype – and implies that these are in opposition, thereby perpetrating a neat binary division of her own. Surely the boundary between the two is fuzzy, and surely there are other contributing factors. Two spring to mind. One is the impact of childbearing on women’s lives. The other is the fork-in-the-road effect, in which a marginal initial preference is amplified by vocational choice into a life-determining result. Multiply this scenario many times over, and you can get a divergence that is statistically significant. From Lawrence Bernstein, Menlo Park, California, US When considering sex differences, we must take into account the brain being bathed in hormones, including testosterone and

oestradiol, which occur in very different amounts in most men and women. Cases of surgical and chemical castration, and of testosterone supplementation, show that testosterone levels affect behaviour, emotion, personality and cognition. In addition, the brain is constantly exchanging signals with parts of the body, including those specific to our sex. Tiny differences in brain structure or connectivity could produce significant differences in function. I think we need to keep an open mind regarding sex differences of embodied brains.

Some particles may be more equal than others From Roy Harrison, Verwood, Dorset, UK Brian Pollard reminds us that atmospheric particulate pollution

from cars comes from the tyres and brakes as well as exhausts (Letters, 2 March). Particles are responsible for most of the loss of life expectancy associated with air pollution. What concerns me is that the word “particle” is being used to cover a multitude of sins. Petrol cars produce a lot of exceedingly small (30 nanometre) carbon-based particles. Diesel cars made since 2011 release mostly droplets of engine oil and nitrate particles. All car brakes release particles of iron, iron oxide and resins; and tyres emit particles of rubber, carbon and silica. It seems unlikely, given the huge range in both size and nature of particles, that the standard measurement of air pollution – weight of particles per cubic metre – is a meaningful guide to their harmfulness to us. One might guess that smaller particles will be more harmful

because there are more of them per gram and they will be able to enter the human body more easily. What data do we need to make meaningful decisions?

Great goblets of fire in several ages past From Lucy Wills, London, UK You report a 3D-printed dichroic goblet that looks brown when reflecting light and purple when light shines through it (9 March, p 12). Such effects have long been treasured. Some Victorians were obsessed by jewellery with dichroic “saphiret”, made by mixing molten gold and glass. Its production ended when gold got too costly, and is now sought after. From Joe Oldaker, Nuneaton, Warwickshire, UK The makers of the plastic goblet >

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LETTERS are a bit behind the curve. The colour of the 4th-century Roman glass “Lycurgus cup” in the British Museum shifts from red to green. The editor writes: Q The researchers do mention the Lycurgus cup in their paper (doi.org/c27r). They suggest that since only it and six other broken pieces found worldwide show the dichroic effect, this may have been due to serendipity rather than to mastery.

Spotting black leopards in Kenya in 1956 From Nick Blackstock, Wilsden, West Yorkshire, UK You published a photo of a black leopard in Kenya, saying it may be the only image of a fully wild black leopard in Africa in a century (23 February, p 28). I was a national service conscript posted to Kenya between 1954 and 1956. We became very familiar with all the local wildlife, sometimes more familiar than comfortable in the circumstances. Early in 1956, I was one of a dozen squaddies who disturbed

a pair of black leopards high in the Aberdare mountains. They made off quickly, but we were sure they were black leopards, not serval cats. That a military patrol could, by sheer accident, come across a pair of these animals seems to suggest sightings weren’t too rare.

Another approach to milk production is possible From David Clarke, Seaford, East Sussex, UK You report the idea of CRISPR gene editing to limit the number of unwanted male calves born to dairy cows (9 February, p 13). Surely it isn’t beyond us to develop a breed of cattle that lactates without giving birth? I do accept that there may be ethical or moral issues with this proposal.

How to hack many cars at once and jam a city From Sam Edge, Ringwood, Hampshire, UK You quote Simon Parkinson suggesting that a coordinated cyberattack on smart cars would take a lot of resources, so

problems with such vehicles that result in gridlock may be more likely to result from a botched software update (9 March, p 8). But cars have a lot of hardware and software in common – for example “smart” alarms. Flaws are likely to be present in models from different manufacturers. A weakness that gave remote access to cars’ on-board control networks could allow a person to disable many vehicles using only an internet-connected computer. Perhaps they could use satnav systems to select cars in a given area for maximum disruption.

It is Scotland’s water, fatbergs or no From Susan Forde, Scotlandwell, Perth and Kinross, UK Kelly Oakes gives a fascinating and worrying account of fatbergs (26 January, p 22). But she claims that remedial action isn’t easy because UK water companies are privately owned. In England and Wales they are. However, the water companies in Scotland and Northern Ireland are public.

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Papillomavirus is also involved in penile cancer From Guy Cox, St Albans, New South Wales, Australia Jonathan R. Goodman’s report on the causes of cancer is interesting and valuable (9 February, p 34). It mentions the link between human papillomavirus and cervical cancer – but not penile cancer, which the virus may also cause. In Bali, penile carcinoma was the most common cancer in men in 2013. Male circumcision may help prevent both cancers.

A share in the credit for stomach ulcer research From Ron Painter, Claremont, Western Australia You report possible links between mouth bacteria and Alzheimer’s, and note doctor Barry Marshall won a Nobel prize for linking Helicobacter pylori and stomach ulcers (2 February, p 6). Robin Warren initiated that idea, began the research and shared the prize.

For the record Q A spacecraft that slingshots around Jupiter gains energy by slowing the planet in its orbit (16 March, p 10). Q The SPF rating of standard sunscreen is primarily a measure of protection against UVB rays (16 March, p 28). Q The “Düsseldorf patient” seems to be cleared of reproducing HIV virus, though a few tests gave positive signals. These may be false positives, non-infectious virus fragments, or whole virus that couldn’t reproduce because of a lack of susceptible immune cells (9 March, p 12).

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 | 30 March 2019

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Tell us what you think at [email protected] ACROSS

7 Inaccurate articles now OK in online community (6,7) 8 Herbs absorb potassium, oxygen and uranium in exercises (8) 9 Summit’s tenth primate? (4) 10 Sign of goodness shown by short piece of DNA – one from group 17 (7) 12 Topless comedian makes organic compound (5)

14 Injection of energy that’s all around (5) 16 Analyse what used to be an organic compound? (7) 19 Snakes like a little time (4) 20 Journalist in food store has excessive concern for details (8) 22 Psychoactive fungus in space behind wise men, around soft substance (5,8)

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DOWN

1 Mint merchant (4) 2 Some writing ink going in tree (6) 3 White record starts to entertain neighbours (7) 4 Breadmaker in unknown direction (5) 5 Work in chairs is getting nervous (6) 6 Seabird swallows coral and large plant (4,4)

11 Someone who doesn’t remember a cinema’s construction (8) 13 Team in cricket match almost look to become rusty (7) 15 Piece of samosa I consider an artwork (6) 17 We run a mile, partly backwards, in dung (6) 18 After bath, woman sends unwanted emails (5) 21 Source of potato, perhaps (4)

Answers to quick crossword No28 ACROSS: 8 PARABOLA, 9 OSMIUM, 10 TERESHKOVA, 11 ALGA, 12 ANOXIA, 14 KINETICS, 15 FOURIER, 17 FISSILE, 20 RED GIANT, 22 OSSIFY, 24 IDEA, 25 AXON REFLEX, 27 ASTHMA, 28 HAPLOIDY. DOWN: 1 BALEEN, 2 YALE, 3 COCHRANE, 4 BAZOOKA, 5 DOMAIN, 6 SMEAR TESTS, 7 SURGICAL, 13 XEROGRAPHY, 16 OVERDOSE, 18 ISOTROPY, 19 ATROPHY, 21 AVATAR, 23 FIELDS, 26 FLOC

Answers and the next Quick crossword in the 13 April issue

30 March 2019 | NewScientist | 55

For more feedback, visit newscientist.com/feedback

FEEDBACK

PAUL MCDEVITT

perhaps naphthalene? “The company ought to know better than to signify its scientific expertise with a diagram of a notoriously toxic polycyclic aromatic,” says Izzy.

A PARLIAMENTARIAN has come up with an incisive solution to the pressing issue of knife crime in the UK. Scott Mann, MP for North Cornwall, shared his suggestion on Twitter: “Every knife sold in the UK should have a GPS tracker fitted in the handle. It’s time we had a national database like we do with guns. If you’re carrying it around you had better have a bloody good explanation, obvious exemptions for fishing etc.” Thousands of Twitter users immediately began skewering the idea. Would existing knives need to be retrofitted with tracking systems, they wanted to know, and if so, with what power source? “Sorry, I forgot to charge the knife” isn’t likely to cut it with the family sat waiting for dinner. Feedback can’t help wondering where it could all lead. To address the power problem, perhaps knives might be taped to vehicle satnav sets as a stopgap solution. Simply carve Sunday’s roast dinner in your car before dashing back inside, or better yet, host your dinner parties in its stylishly

upholstered interior. Then on to the next dilemma: is a geo-linked knife dishwasher-safe? Cornwall has an historically important fishing industry, which might explain why Mann says fishing ought to get a free pass. But Feedback worries that this exemption is just the kind of oversight that could lead to errant youths donning sou’westers and cable-knit jumpers, shrugging off the double edged “pilchard knives” in their tackle boxes. Trackable knives would at least be a boon in university halls of residence, allowing students to know which washing-up dodger had accumulated the communal cutlery in their room. That makes us think that, if we are adding GPS trackers to the silverware, we really should start with teaspoons. EIGHT-POINTED snowflakes are a familiar design crime to Feedback readers. But what to make of Colgate’s use, in advertising material spotted by reader Izzy Hanson, of a pair of carbon rings to illustrate the science packed into every tube of toothpaste? Is it

“Florida newspaper The Villages Daily Sun informs Andrew Doble that ‘researchers in southern California have recaptured a female mountain, and treated it for mange’.” 56 | NewScientist | 30 March 2019

OPIUM-addicted parakeets are plaguing poppy farmers in India. The Asian News International news agency shared footage of the feathered bandits attacking the swollen poppy heads, and even flying off with them after chewing through the stem. The plantations in Madhya Pradesh are licensed to grow poppies as a source of opiates for pharmaceutical use. But local parrots have taken a shine to the crop, and farmers are worried that the plant’s addictive qualities keep them coming back for more. “We have tried making loud sounds and even use firecrackers to scare the birds. But nothing has helped,” opined one farmer. IN THE US, a bill introduced to the Georgia state legislature would require men over 55 to report to the nearest authorities every time they ejaculate. HB 604 also proposes a ban on vasectomies, requires men to obtain permission from their partner before prescriptions for erectile dysfunction medicine can be fulfilled, introduces a 24-hour waiting period for men wanting to buy pornography and makes sex without a condom punishable as aggravated assault. Not expected to pass, the bill aims to highlight attempts to tighten abortion laws in the state. Dar’shun Kendrick, a politician in the Georgia House of Representatives, is one of the bill’s co-authors. She posted her “testicular bill of rights” on Twitter, declaring: “You want some regulation of bodies and choice? Done!”.

MEANWHILE, Lorna Cox was shocked to read the following admission from our colleagues: “Despite making up most of the universe, we still haven’t detected dark matter” (9 March, p 37). “I didn’t realise New Scientist had made it all up,” says Lorna. Well, somebody has to.

OUR call for scientifically sensible nursery rhymes has produced some sparkling entries – albeit perhaps also showing the ability of science to make the wondrous distinctly prosaic. When Butch Dalrymple Smith was a child, he would chant: Twinkle Twinkle little star, I don’t wonder what you are. You’re the cooling down of gases, Turning into solid masses. In much the same vein, Galen Ives shares a verse dedicated to the first artificial satellites: Twinkle, twinkle little star I don’t wonder what you are. I surveyed your spot in space Before you left the missile base, And I shudder when I think What you’re costing us per twink!

BBC News, responding to revelations of how much plastic the drinks company Coca-Cola uses, points out: “It’s hard to visualise what three million tonnes looks like. But everyone can picture a blue whale. Now picture 15,000 of them. That’s roughly three million tonnes.” Much clearer – and at last with the blue whale we have an appropriate unit for ocean pollution, says Bob Willis, who spotted this gem.

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 Many ridges to cross Back roads in Australia often have hundreds of metres of gravel corrugations, or ridges. They are always a few centimetres high, spaced about 30 centimetres apart… and annoying for vehicle occupants. What causes them?

Over time, these undulations are exacerbated by bouncing truck and car tyres. Wind and rain remove loose dirt between ridges, accentuating them. If your vehicle has feeble city tyres, not big, boofy, four-wheeldrive ones, go slowly. With either type, you can minimise the jarring by reducing tyre pressure, especially if the corrugations combine with the angular rocks of the gibber plains – the desert landscape encountered on the

Q When a vehicle is driven over an unsurfaced road, its weight indents the material under the tyre. The loose particles ahead of the tyre tend to be pushed “Some people drive on the forwards, creating a small ridge. wrong side of corrugated Each passing vehicle gradually roads, as it feels smoother raises the ridge, until the rate of that way” material removal from the crest due to abrasion and impact stop it getting any taller. The maximum unsurfaced Oodnadatta Track height of the ridge depends on the in South Australia. I know this material used for the road. from personal experience. The surface of a newly levelled Bonita Ely road generally stays more or less Marrickville, New South Wales, smooth until it rains. After this, it Australia corrugates rapidly, presumably because indentation can occur Q I live by a gravel road in rural Western Australia. Corrugations more easily with wet materials. are common and aren’t restricted Such ridges also occasionally to back roads. They start small and occur on bitumen roads. I used increase in size over time, until to pass a bus stop on a downhill you are unsure whether to slow slope in Sydney that developed down and feel each bump or just impressive corrugations due to go faster and ride across the tops heavy buses halting there. of the ridges. Tony Cooke Corrugations form across the Macgregor, ACT, Australia road, and are steeper on the side facing traffic flow. That is why Q Gravel and dirt roads are maintained to try to keep the some people drive on the wrong surface in good condition, for side of the road when they can, example by scraping them with as it feels smoother that way. a wide blade mounted under a The material used for the road heavy vehicle. The blade bounces is an important factor in the slightly, creating undulations. corrugations. The road we live on

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has two sections: the part covered with sand and gravel is corrugated, while the other, made with gravel and some clay, sets hard and is always in excellent condition. If motorists slow down, the likelihood of ridges forming is cut. Anna Butcher Brookton, Western Australia Q The amplitude of the ridges depends on the size of wheels, the speed of vehicles and to some extent vehicle length. Larger wheels yield deeper corrugations. Higher speeds produce longer spaces between corrugations. So small vehicles using roads more usually frequented by larger, slow vehicles are worst affected. Australia’s unsealed roads are much used by large vehicles, so they develop long stretches of corrugations. Cars can minimise the bumpiness by going faster and essentially riding along the tops of the corrugations. But this is dangerous because the vehicle isn’t in contact with the ground for significant periods of time, meaning it is easy to lose control of the steering. Brian King Barton on Sea, Hampshire, UK Q The ridging effect is known as washboarding. It occurs on all loose surfaces, including sand and snow. It is caused by a force acting in one direction on a movable surface, much like ripples on a lake caused by the wind. The ridges are essentially very slow waves. It helps to use a mix of particles

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of different sizes to make the road surface, as this prevents the material from moving as easily. Lewis O’Shaughnessy London, UK

This week’s questions

ARACHNID APPETITE

I was impressed by the size of the prey captured by this crab spider (see photo), seeing as they don’t use webs to catch food. How much of it would the spider eat and is there a “best before” date? Hugh Meteyard Theydon Bois, Essex, UK FEELING FLY

Do insects have emotions in the same way humans and mammals do? For example, would a fly feel sad if it saw its brother die? Jake Jackson Guisborough, North Yorkshire, UK