22 June 2019 New Scientist

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THE WORST PLANETS

Hellish truth about Mercury and Venus

ANCIENT ‘SISTINE CHAPEL’

3000-year-old Hittite mystery finally solved

RISE OF SUPERWEEDS

Coming soon: plants that resist all herbicides WEEKLY 22 June 2019

SPECI A L ISSUE

THE HUMAN BRAIN

Understanding the most complex object in the known universe Why our brains are so special

How smarter people’s brains are different

What happens when you think

Why your brain never turns off

Left brains and right brains How to make a brain How your gut influences your mind

Why some brains are more resistant to decline

Where consciousness comes from No3235 £4.95 CAN$7.99

2 5

PLUS DO PROTESTS WORK?/ PANCAKE SCIENCE /ROBOT IRONY/ OUR STRANGELY QUIET BLACK HOLE / VERTICAL FARMING

9 770262 407312

Smart technology does more than take selfies. From helping pilots avoid turbulence to making cars more intuitive to reinventing retail, IBM is working behind the scenes to change the way the world works. Find out how at ibm.com/smart/uk

This week’s issue

On the cover

Coming next week

42 The worst planets Hellish truth about Mercury and Venus 8 Ancient ‘Sistine Chapel’ 3000-year-old Hittite mystery finally solved

34 The human brain Understanding the most complex object in the known universe

12 Rise of superweeds Coming soon: plants that resist all herbicides Covertly conscious People in long-term comas may be more aware than we knew

20 Do protests work? 12 Pancake science 14 Robot irony 7 Our strangely quiet black hole 15 Vertical farming Vol 242 No 3235 Cover image: Sofia Bonati

News

Features

6 China organ transplants Inquiry says organs are still being taken from prisoners

34 The human brain The more we learn about our command centre, the more mysteries arise

News

10 Net zero emissions UK to commit to ambitious climate goal

42 The worst planets Mercury and Venus are two of Earth’s closest cousins. So how did they turn out so hellish?

14 Undetected Ebola More than half of all outbreaks may go unrecognised

The back pages Views

51 Maker How to make a disco ball TUNART/GETTY; TOP: PETER STRAIN

23 Comment We must understand the roots of “anti-vax”, says Furaha Asani 24 The columnist Graham Lawton on religion and climate change 26 Letters There are more ways to profit from going green 28 Aperture Can you spot the common potoo in this image? 30 Culture A podcast about women’s sexual health will change lives

52 Puzzles Quick crossword, a prison puzzle and a short quiz 53 Feedback Metric madness and climate sewage

8 Mystery solved? Hittite carvings may be an ancient calendar

24 Columnist

“Secularism, religion and environmentalism are entwined in ways that have scarcely been explored”

54 Almost the last word Why eyeballs don’t freeze and the nature of dust 56 Me and my telescope Anthropologist Ruth Mace on the people of western China

22 June 2019 | New Scientist | 1

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The leader

Your incredible brain

EZRA BAILEY/GETTY

The awesome lump between our ears is hard to fathom – and that’s fantastic PHYSICIST Emerson Pugh once said that if the human brain were so simple that we could understand it, we would be so simple that we couldn’t. Thankfully, the complexity of our brain is so great that we are not simple and neither, therefore, is the task of understanding it. However, it can feel like a Herculean feat to establish even basic facts, such as how many kinds of brain cell we have. Our latest attempt to count them suggests there are 75 types just in the neocortex, the area responsible for our most advanced thoughts and behaviours. That isn’t to say our efforts to unravel the brain’s mysteries are in vain (see page 34). Despite Pugh’s observation, we are learning ever more about how a 1.5-kilogram lump of tissue that flutters and crackles inside our skull can come up with our most elaborate – and even

The human brain may be a modest 1.5 kilograms in weight, but it is astonishingly complex

annoying – behaviours. Yet each new insight raises more questions, and also casts age-old problems in new light. Breakthroughs in understanding how our brains stitch together our perception of reality are redefining what it means to be conscious. They also highlight the persistent power of the mind, even in cases when our bodies hide all signs of awareness (see next week’s issue). We don’t appear to be heading towards a world of jars full of brains, bodies

discarded, just yet though. Our brainbody connection has never been so robust. Gut thinking is no simple turn of phrase: microbes in our intestines affect our risk for neurological conditions, and influence our mood and mental health. And when it comes to preventing cognitive decline, physical activity is paramount. Still, let’s not reject a sci-fi future entirely – we know, for instance, that magnetic stimulation can have many uses, from treating depression to supercharging our brain’s processing power, effectively making us smarter. The human brain has many more revelations in store, and they may require us to rethink old ideas or correct our assumptions. But that should come as no surprise. After all, between our ears lies the most complex object in the known universe. ❚

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S E N S A T I O N A L S I X    Ι                  

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News Inventive minds People with narcolepsy are more creative p7

Exomoon origins Witnessing the birth of a satellite around a distant world p10

Perfect pancakes Fluid dynamics reveals the best way to make crêpes p12

Robot personality Machines learn to use irony to make us like them p14

Strange cells A special kind of fat in our bones behaves oddly p15

Health

Microbe mix may prevent asthma

STEFFEN M. OLSEN/DANISH METEOROLOGICAL INSTITUTE

CHILDREN who grow up on farms have a lower risk of developing asthma and now it seems that may be due to microbes that can also be found in non-farm homes. Pirkka Kirjavainen at the National Institute for Health and Welfare in Finland and his colleagues studied about 400 children who lived on farms or in rural, urban or suburban homes. They found that those who grew up on farms had the lowest risk of developing asthma, but children raised in non-farm homes with a similar mix of microbes to a farm also had a lower risk (Nature Medicine, doi.org/ c7df). ❚ Chelsea Whyte

Melting ice in Greenland

Animals

This month has seen temperatures tens of degrees higher than normal in Greenland, reports Michael Le Page

The evolution of puppy dog eyes

THIS extraordinary photograph was taken by climate scientist Steffen Olsen of the Danish Meteorological Institute on 13 June. With the help of local hunters, his team was retrieving instruments from the sea ice in Inglefield Fjord in Greenland. The dogs are running on sea ice that is still 1.2 metres thick. Sudden warming caused the surface to melt and form a shallow layer of water on top of the ice below. “The photo documents an unusual day. I learn now that it is even more symbolic than scientific to many. Tend to agree,”

Olsen tweeted after the image went viral online. This June has seen temperatures more than 20°C above normal in Greenland, leading to extensive surface melting across large areas of the ice sheet on the vast island as well as of the sea ice around it. According to the National Snow and Ice Data Center in the US, more than 40 per cent of the ice sheet’s surface was melting at one point, which is the highest level recorded at this time of year. The highest level of surface melt at any time of the year was in July 2012, when 97 per cent of the ice

Climate change news Go online for all the latest on our warming world newscientist.com/climate-change

sheet was melting. Greenland’s ice sheet, which is more than 3 kilometres thick in places, holds enough water to raise global sea level by 7 metres. According to a 2012 study, all this ice will melt if the world keeps warming. The loss of more sea ice each summer, by contrast, doesn’t raise sea level. But it gets replaced with dark water that reflects less sunlight, which results in yet more warming – a feedback loop that adds to the temperature rise across the Arctic. There is growing evidence that Arctic warming is leading to more extreme weather across the northern hemisphere, by altering the behaviour of high level winds known as the jet stream. ❚

HUMAN selection has seen dogs evolve a muscle that allows for expressive faces. It means they can lift their inner “eyebrow”, making their eyes seem larger and their faces sad – the familiar “puppy eyes” look of dogs. Juliane Kaminski at the University of Portsmouth, UK, and her team dissected six dogs and four wolves, none of which died for the study. All but one dog had a muscle on the inner side of the eye near the nose, but none of the wolves had it. Kaminski thinks this muscle evolved because people favoured dogs that could make this expression (PNAS, doi.org/c7dd). ❚ MLP 22 June 2019 | New Scientist | 5

News China inquiry

Forced organ transplants Inquiry suggests prisoners are still being used as organ donors in China

EXECUTED prisoners are still being used as organ donors in China, according to an inquiry set up by a campaign group. The Chinese government previously said it had stopped this practice four years ago. But this week, the chair of the tribunal, Geoffrey Nice, said he believes it is still widespread. The inquiry in London was initiated by campaign group the International Coalition to End Transplant Abuse in China and has no legal power. It was asked to investigate whether some

the organs would be sourced from Falun Gong members. Some websites advertise in English for foreign patients to visit Chinese hospitals for transplants, says David Matas, a Canadian human rights lawyer. Selling organs to foreigners is against an international convention known as the Declaration of Istanbul. People who had been released from detainment camps in China testified at the inquiry. Some said they had been forced to have medical checks of their internal organs, such as ultrasound scans. However, all this evidence is circumstantial, and no one has directly observed or proved that transplant organs are still being sourced from prisoners. There have been claims for decades that prisoners were being used as organ donors in China. Several thousand transplants were reported in the country every year, yet until recently there was little public understanding of the concept of brain death, says Jacob Lavee, an Israeli heart surgeon who is a member of campaign group Doctors Against Forced

hospitals in China are still boosting supplies of transplant organs from prisoners, and whether these include political prisoners and members of ethnic groups, such as Uighur Muslims and followers of Falun Gong, a belief system banned in China. The tribunal heard evidence that some hospitals in China offer organ transplants with very short waiting times. This would be impossible without a large bank of people with known tissue types who can be killed to order, said Nice, a former UK judge. The tribunal was told of a 2018 probe by the World Organization to Investigate the Persecution of Falun Gong. Researchers pretending to be doctors rang up senior transplant doctors in Chinese hospitals to try to book transplants. Some were offered waits as short as one or two weeks. In nine of the 12 hospitals, doctors verbally confirmed that Most organs worldwide are donated by people classed as brain dead 6 | New Scientist | 22 June 2019

HUANG XIN/XINHUA/EYEVINE

“We know that political prisoners in China are subjected to horrific abuses”

LUCY NICHOLSON/REUTERS

Clare Wilson The Falun Gong belief system is banned in China

Organ Harvesting. In other countries, almost all transplants come from people who end up brain dead, but this accounts for less than 1 per cent of all deaths, which is why organs are such a scarce commodity. In about 2010, medical staff in China began to be trained in how to recognise brain death. Around this time, public campaigns to get people to register as voluntary organ donors began, and the Chinese government said organs stopped being taken from prisoners in 2015. But earlier this year, Lavee and two colleagues posted a study online suggesting that there are anomalies in China’s own transplant figures. For example, they said that, during a period in 2016, there were 640 transplants

reported, yet only 30 recorded voluntary donors. This would mean that each donor yielded a medically impossible average of more than 21 organs. In the UK, the average figure is about three. “The Chinese government always follows the World Health Organization’s guiding principles on human organ transplants, and has strengthened its management on organ transplants in recent years,” a spokesperson from the Chinese Embassy in London said in a statement. “We hope the British people will not be misled by rumours.”

Persecution of minorities Patrick Poon of Amnesty International says that his organisation has been unable to confirm if executed prisoners are still a source of organs in China. “We do know that political prisoners in China are subjected to horrific abuses, and we are particularly concerned about the internment of up to a million Uighurs and other Muslim ethnic minorities,” says Poon. However, Nice’s China Tribunal found this week that there isn’t enough evidence to determine whether organs are being taken from Uighur people interned in “re-education camps”. But the inquiry said there was enough evidence to conclude that forced organ harvesting has occurred for years in China, and that “Falun Gong practitioners have been one – and probably the main – source of organ supply”. Adnan Sharif, a British kidney surgeon who is another member of Doctors Against Forced Organ Harvesting, says transplant doctors from other countries should refuse to collaborate with their Chinese colleagues until the unethical practices stop. ❚

Black hole mysteries newscientistlive.com/ first-black-hole Space

Our galaxy’s central black hole is oddly quiet – now we may know why Leah Crane

Those signatures show that the grains are arranged in a sort of spiral pattern similar to that of the Milky Way itself. “For many years, we have studied the high-resolution structure of the gas in this region – the mini spiral of the galactic centre – but we haven’t had the ability to probe the magnetic field on such fine scales,” says Cornelia Lang at the University of Iowa. The strongest force in this location is the gravity from Sagittarius A*, the Milky Way’s central supermassive black hole.

Even though the magnetic field is weaker than the gravity, the team found that it is strong enough to overcome turbulence in the dust and gas and shepherd them into the spiral shape observed. That spiral eventually brings the debris into orbit around the black hole, says Dowell. He presented the work at a meeting of the American Astronomical Society in St Louis, Missouri. The lines show streams of dust being pulled around the Milky Way’s black hole

NASA/SOFIA; STAR FIELD. NASA/HUBBLE SPACE TELESCOPE

THE Milky Way’s supermassive black hole is eerily quiet, rarely devouring anything. Now it seems that magnetic fields in the centre of our galaxy could be responsible, by steering gas and dust into orbit around the black hole rather than allowing them to drop in. Darren Dowell at NASA’s Jet Propulsion Laboratory and his colleagues used a camera aboard the agency’s Stratospheric Observatory for Infrared Astronomy (SOFIA), which is a telescope on a high-flying airplane, to look at the infrared light from the centre of the galaxy. This sort of light is completely blocked by Earth’s atmosphere, so the only way to observe it is to fly high above the ground or to use a space telescope. The infrared light the team observed was emitted by grains of magnetic dust floating amid the dust in the central 16 light years of the galaxy. The grains align with their long axes perpendicular to the direction of the magnetic field, which leaves an observable signature in the light they emit as they spin.

But it seems like the magnetic field isn’t funnelling the material directly into Sagittarius A*, which very rarely eats anything substantial. We know that because we almost never see the bright outbursts that occur when matter falls into a black hole. Instead, it seems to be channelling the gas and dust away from the black hole’s event horizon, the boundary around a black hole from beyond which nothing can emerge. Magnetic fields are constantly shifting, so if the field at the galaxy’s centre changes shape, Sagittarius A* could start feeding again, says SOFIA team member Joan Schmelz. That would shake up the Milky Way, resulting in huge amounts of radiation and powerful winds that could blow material right out of the galaxy, a phenomenon we have seen in other, more active galaxies. Thankfully, Earth is far enough away from the galactic centre that it wouldn’t affect us, says Farhad Zadeh at Northwestern University in Illinois. ❚

Psychology

People with narcolepsy seem to be more creative LIVING at the border between wakefulness and a dream world may do wonders for your creativity. People with narcolepsy are excessively sleepy during the day and can often drift off. Isabelle Arnulf, who treats narcolepsy at Pitié-Salpêtrière Hospital in Paris, noticed that her patients seemed remarkably creative. Many of them were artists and poets, for example. “Even when they were sitting in the

waiting room, they were doodling and writing,” she says. Arnulf and her colleagues asked 185 people with narcolepsy to complete a questionnaire designed to test for creativity. They compared the results with those of 126 people who didn’t have the condition. Thirty volunteers from each group also undertook a creativity test, which involved trying to find new solutions to problems, as well as creative writing and drawing. People with narcolepsy did better on every measured aspect of creativity. For instance, when

participants were asked to come up with a story that ended with the words “… and the last apple fell from the tree”, most composed a version that included Adam and Eve, Isaac Newton or the end of summer. But the most creative responses came from people with narcolepsy, including a story about trees joining a strike initiated by animals who had decided not to feed humans anymore, and another about

“REM sleep helps you make links between things and that’s what creativity is all about”

a bulimic worm called Jean-Jacques (Brain, doi.org/c645). Arnulf thinks this could be because people with narcolepsy experience an unusual sleep cycle. A typical cycle begins with a period of non-REM sleep, but people with narcolepsy usually fall straight into REM sleep – the period when we tend to experience vivid dreams. Penny Lewis at Cardiff University in the UK agrees. “We think REM sleep helps you make links between things that are not obviously linked, and that’s what creativity is all about,” she says. ❚ Jessica Hamzelou 22 June 2019 | New Scientist | 7

News Archaeology

Solving an ancient mystery A 3200-year-old sanctuary may have acted as a calendar that was centuries ahead of its time, finds Colin Barras

OZERGOK/GETTY

Some call Yazılıkaya in Turkey the Sistine Chapel of Hittite religious art

FOR 3200 years they have guarded their secret. The deities carved in limestone near the ancient city of Hattusa are as enigmatic as they are beautiful. Perhaps no longer. A controversial theory suggests the ancient carvings may have functioned as a calendar, with a level of sophistication way ahead of its time. “It’s not only a striking idea, it’s reasonable and possible,” says Juan Antonio Belmonte at the Institute of Astrophysics of the Canary Islands, Spain, who wasn’t part of the work. Hattusa was the capital city of the Bronze Age Hittite empire, based in what is now Turkey. A few 8 | New Scientist | 22 June 2019

kilometres to the north-east of Hattusa are the ruins of an ancient religious sanctuary centred on a large limestone outcrop. Archaeologists believe it was one of the holiest of Hittite sites, but its exact purpose is unknown. Even its original Hittite name is a mystery: today it is known simply as Yazılıkaya, a Turkish term meaning “inscribed rock”. “Yazılıkaya has an aura to it,” says Eberhard Zangger, president of Luwian Studies, an international non-profit foundation. “Part of it is because it’s an unsolved enigma, part of it is the beauty of the place.” The site has been described

as the Sistine Chapel of Hittite religious art for the quality of the rock carvings preserved there. Yazılıkaya and Hattusa have UNESCO World Heritage Site status, and the carvings on the rock have been studied by scholars for decades. But according to Zangger, they all overlooked something. On the northern wall of a roofless limestone chamber at Yazılıkaya, there is a panel on

29.53

The average number of days in a lunar month

which the supreme couple among Hittite gods are carved. On the western and eastern walls, more carved deities form two long processions marching towards the supreme couple. The eastern procession currently contains 17 deities, but Zangger and his colleague Rita Gautschy at the University of Basel, Switzerland, argue there were originally two more based on engraved symbols and deity-shaped gaps. The western procession is divided into two groups: one containing 12 deities and the other 30. Finally, there are curious horizontal benches carved into the rock below each procession. Zangger and Gautschy suggest the Hittites used the carvings as a calendar, keeping time by moving heavy stone markers along the benches beneath the processions. They believe the procession of 30 deities corresponded to the lunar cycle and marked a lunar month, which contains on average 29.53 days. At the beginning of the month, the marker would be placed beneath the deity at the front of the procession, and each day the Hittites shifted it one deity backwards. (Local hieroglyphs are always read in the opposite direction to the way any figures or faces are looking.) Significantly, says Gautschy, if the Hittites started the month with a new moon then, on the night of a full moon, the marker would always lie below one of two unusual bull-like figures in the procession who together hold up a large dish. The researchers say it would make sense for the Hittites to pay particular attention to the full moon because it was the one part of the month

More on ancient civilisations

GETTY

Gerdekkaya is a tomb in the same area and time period as Yazılıkaya

IZZET KERIBAR/GETTY

We know from earlier texts that the idea of three-year intercalation dates back a couple of millennia before Yazılıkaya was built. But conventional wisdom is that it was only about 2500 years ago that the more sophisticated Metonic cycle came into widespread use. “We would probably not expect knowledge of the 19-year cycle in the 2nd millennium BCE,” says Gautschy. If the Hittites did follow such a calendar, they must have been influenced by exceptional astronomers. It isn’t impossible that there was a Hittite equivalent of the astronomer Kepler in Hattusa at the time, says Ian Rutherford, a classicist at the University of Reading, UK. But he says it is odd that there are no traces of such an astronomer in the vast archives of ancient texts that have been discovered in Hattusa. It is one reason why he is sceptical – although open-minded – about the calendar idea. Belmonte, however, is enthusiastic. He has previously shown that many Hittite buildings are aligned to important astronomical events like the summer solstice. He envies Zangger and Gautschy for being the first to notice that the Yazılıkaya deities could have been used to observe a Metonic cycle. “I had this in front of my eyes and I was unable to see it,” he says. Other astronomers are more cautious. “The numbers in play – 12, 30 and 19 – are astronomically suggestive,” says Edwin Krupp, director of the Griffith Observatory in Los Angeles. But he says that is far from proof that the site served as a calendar – a point

GETTY

when a portentous lunar eclipse might occur. When the marker lay below the deity at the rear of the procession, the month was up and the Hittites would have moved the marker back to the front of the procession to start again, say the researchers. At the same time, the Hittites moved a second marker that lay below the procession of 12 deities, and so helped them track the passing months. But performing these two operations alone isn’t enough to make an accurate calendar, because 12 lunar months add up to only about 354.36 days. The calendar can be brought roughly back in line with the solar year – about 365.24 days – by adding a 13th “intercalary”’ month every third year, meaning a total of six additional months are added over an 18-year period. Even then, however, the calendar still drifts. This drift can be largely removed by adding an additional intercalary month every 19th year – making the timepiece run on what is known as the Metonic cycle. Zangger and Gautschy suggest that the Hittites used the procession of 19 deities on the eastern wall to keep track of this. They think a stone marker was moved along this procession once a year to help the Hittites work out when to add extra months over a 19-year cycle (Journal of Skyscape Archaeology, DOI: 10.1558/jsa.37641).

PAUL WILLIAMS / ALAMY STOCK PHOTO

Long-lost Amazon cities were once home to millions newscientist.com/amazon-cities

Researchers believe ancient Hittites used 12 deities to mark the passing of lunar months

Gautschy is keen to stress too. Krupp also sees a couple of problems with the calendar idea. Because of the nature of the site’s preservation, we can’t be sure the third group originally contained 19 deities. If there were just the 17 it now contains, the Metonic-like pattern breaks down. What’s more, many of the deities depicted at Yazılıkaya have their names carved into the rock. The calendar idea would suggest that each deity name would be associated with a particular day of the month or month of the year, says Krupp – but he points out there is little in the Hittite texts to suggest this was the case.

In fact, says Rutherford, the Hittite written records seem to paint a picture of a society that was remarkably unconcerned about the heavens. “That may have something to do with the climate: it rains a lot in the Anatolian highlands,” he says. Cloud cover might have impeded careful astronomical observations. But Zangger thinks Hittite scholars place too much emphasis on the texts. For instance, archaeological evidence shows the Hittites were impressive hydraulic engineers, but Zangger says they left no records on the subject. “Hittite society consisted of more than is reflected in the documents,” he says. “Perhaps the carvings really are just gods walking in a certain sequence – but there seems to be so much more to it.” ❚ 22 June 2019 | New Scientist | 9

News Climate policy

Exomoons

UK raises climate goal to net zero carbon by 2050

The live birth of a planet and its moons

Adam Vaughan

Leah Crane

THE UK is to set itself the most ambitious long-term climate target of any major country: to become carbon neutral by 2050. It is being seen by many as a bid by outgoing prime minister Theresa May to build a legacy beyond Brexit. “Now is the time to go further and faster to safeguard the environment for our children,” she said in a statement last week. The net zero target is a dramatic raising of ambition from the existing UK target of an 80 per cent cut in emissions by 2050. Under net zero, some industries are likely to still emit carbon by mid-century, but these would be offset by other measures, such as tree planting, that suck carbon from the air. The decision to push ahead with the tougher goal comes despite grumbles about it from parts of the government. Earlier this month, the Treasury said that moving to net zero would cost in excess of £1 trillion by 2050 – more than government advisers had said – and the 10 | New Scientist | 22 June 2019

implications should be better understood before enacting the target. In an apparent nod to these concerns, Downing Street promised a review within five years, to see if other countries are taking similar action and to check that “industries do not face unfair competition”. Boris Johnson and Jeremy Hunt, two of the frontrunners in the race to lead the Conservative party and become the UK’s next

11

years since the UK’s last major climate change legislation

prime minister, have both said they support the new goal. It was also welcomed by the government’s adviser on global warming, the Committee on Climate Change (CCC), which had called for the stricter target in May. And it follows months of protests by school pupils and campaigners calling for tougher action (see “Do protests work?, page 20). The Confederation of

British Industry also says it is “the right response to the… climate crisis”. However, the government says it would “retain the ability to use international carbon credits”. This can involve paying other countries to make carbon cuts on the UK’s behalf to count towards the target. The CCC advises against this, saying the target should be met within the UK’s borders. The goal has been introduced as a draft amendment to the Climate Change Act 2008, but MPs will need to vote for the measure before it becomes law. Only three MPs voted against the original law 11 years ago. One way to get close to net zero by 2050 would be to replace natural gas with hydrogen. A report by the Institution of Engineering and Technology last week concluded that using hydrogen for heating, power and industry would be safe. However, the report revealed that this would require a hike in hydrogen production to 10 times current levels. Norway also made climate moves last week, with its MPs backing a decision to divest the country’s $1 trillion sovereign wealth fund from oil and gas exploration firms and invest more in renewable energy. The fund, known formally as the Government Pension Fund Global, will gradually sell off an $8 billion stake in 134 oil and gas firms. But the shift will only affect companies solely involved in fossil fuel exploration, not those such as Shell and BP which also have renewable energy business arms. ❚

ABOUT 370 light years away, a planet is being born, possibly with its own set of rings or moons. In 2018, astronomers spotted a young world growing around star PDS 70. Now they have observed what appears to be a disc of debris orbiting the planet, the same sort of disc that we think can coalesce into a moon. Faustine Cantalloube at the Max Planck Institute for Astronomy in Heidelberg, Germany, and his colleagues used the Very Large Telescope in Chile to examine the spectrum of light coming from the planet, PDS 70b, and found that it appeared to be emitting more infrared light than we would expect for a planet alone. The infrared light indicates that something above the planet’s surface is being heated as it absorbs light from the planet and re-emits it at a longer and redder wavelength. The team compared the data with models that included a planetary atmosphere or a disc of dust and gas, and found that the disc was a far better match (The Astrophysical Journal Letters, doi.org/c698). “The planet is very young, so it’s hot and bright and it’s heating up this dust around the planet,” says Cantalloube. This is the first time we have spotted a disc around a young planet. Some material from the disc is probably falling onto the planet and helping it grow, but eventually the disc may flatten out to form rings like Saturn’s or clump up and create moons. We have never before definitively spotted a moon around a planet outside our solar system. ❚

ESO/A. MÜLLER ET AL.

STEPHEN CHUNG/LNP/SHUTTERSTOCK

Protesters want more drastic action on emissions

Planet PDS 70b (the light circle) is forming in the protoplanetary disc of star PDS 70

News Evolution

Rise of weeds we can’t kill Pest plants are evolving to resist our most powerful herbicides Michael Le Page

loss of natural habitat. The latter is the single greatest threat to wildlife and biodiversity. The latest worry is a plant called blackgrass. “It can totally infest a field to the extent you can barely see the crop,” says David Comont of Rothamsted Research in the UK. Strains of blackgrass (Alopecurus myosuroides) are already resistant to certain herbicides, and some are resistant to several at once. Glyphosate is often the last line of defence. Comont tested blackgrass from more than 100 fields in the UK and found that it is evolving resistance to this weedkiller too (New Phytologist, doi.org/c7bg).

In the US, several weeds are on the brink of becoming resistant to all herbicides that can be used on certain crops – soya beans for example. Growers of this use eight classes of herbicides that kill weeds in different ways, says Davis. But some strains of a problem plant called tall waterhemp (Amaranthus tuberculatus) are resistant to five of these classes of herbicides. “This is a very large problem,”

“Superweeds will cause major crop losses, speed up climate change and harm wildlife”

POWERED BY LIGHT/ALAN SPENCER/ALAMY STOCK PHOTO

THE most damaging weed in the UK is about to become resistant to the main defence farmers have against it – the weedkiller glyphosate. Other countries around the world are facing similar problems, which could decimate food crops. Many weeds have evolved resistance to several different kinds of herbicides, and some are set to become resistant to all the herbicides used on particular crops. These superweeds will cause major crop losses and push up food prices. They will also speed up climate change and harm wildlife as even more land is converted for farming to make up for the lower yields. “It is not a matter of if but when we are going to be losing chemical control of these weeds,” says Adam Davis at the University of Illinois at Urbana-Champaign. In Europe, it is estimated that weeds resistant to the herbicide glyphosate will cause yields of wheat, barley and oilseed rape to fall around 10 per cent, causing a loss of produce worth around €2 billion to farmers. An additional 2 million hectares of farmland would be needed to compensate, resulting in higher greenhouse gas emissions and a

says Davis. “Many different weed species in many different parts of the world and many different cropping systems are developing resistance.” Both Davis and Comont compare the situation to the rise of antibiotic-resistant microbes. The cause is the same – the overuse and misuse of antibiotics and herbicides leads to rapid evolution of resistance. But this evolution can be prevented. The key is to combine lots of different ways of controlling weeds so the plants never have a chance to evolve resistance to any one method. That might mean rotating crops, growing crops at a different time of year, combining herbicides that kill in different ways and so on. The trouble is that farmers who do the right thing make less money in the short term. Economically speaking, there are no disincentives for overuse of weedkillers, says Davis. It is possible to control weeds without synthetic herbicides, as organic farmers do, but it is more difficult and more expensive, and yields are usually lower. For instance, hand weeding is effective, but very costly because it is so labour intensive. ❚

Fluid dynamics

Maths reveals how to avoid a crummy crêpe THIN and crispy in spots, chewy or underdone in others – that is no way to serve a crêpe. It is easy to get uneven results when cooking these treats, but a mathematical analysis has revealed how to handle a pan to rustle up a perfect pancake. Mathieu Sellier at the University 12 | New Scientist | 22 June 2019

of Canterbury in New Zealand and Edouard Boujo at the Ecole Polytechnique in France modelled the fluid dynamics of crêpe batter in a heated pan. To them, a crêpe should be uniformly thin, free of holes and perfectly circular. That is easier if using a wooden crêpe spreader, but they assessed how to achieve this just by moving a pan. The pair modelled the variables involved: the effects of gravity and temperature on the batter as it

spreads, the tilt and rotation of the pan as well as the cooking time. They found that uniformity of crêpe thickness depends on pan motion and the steady increase in viscosity of the batter as it cooks. They say that the best method starts with pouring batter into a very hot pan, then steeply tilting it so the liquid flows to the rim. The steep angle keeps the fluid moving as it heats up and starts to solidify. Next, rotate the pan, while still

inclined, in a circle to coat the full circumference of its cooking surface with the batter. While completing this circular motion, decrease the tilt of the pan until it is horizontal, and let the crêpe cook to your taste. Then flip and enjoy. This leads to 83 per cent more uniformity than just plopping the batter in the pan and letting it spread on its own (Physical Review Fluids, doi.org/gf3tc4). ❚ Chelsea Whyte

News Infectious diseases

Ebola going undetected More than half of all outbreaks of the deadly virus are missed Ruby Prosser Scully Protective suits can stop the spread of Ebola via body fluids

REUTERS/GORAN TOMASEVIC

animals. Emma Glennon at the University of Cambridge and her colleagues suspect that, when it enters the human population, Ebola often dies out before it can grow into a medical emergency. To test the idea, Glennon’s team used computer modelling informed by data sets related to the West Africa epidemic. After taking into account the factors that determine the likelihood of the virus passing from person to person, they estimated that more than half of spillover events go undetected, implying that well over 100 outbreaks of Ebola have never been picked up by medical monitoring. One of their models suggested that the undetected spillover figure might be as high as

AT LEAST half of all Ebola outbreaks may go unrecognised, and more surveillance is needed to identify them. Those are the conclusions of a new analysis of data from the largest Ebola outbreak in history. The study has been published amid the second-largest Ebola outbreak in history, which is currently affecting the Democratic Republic of the Congo. Since that outbreak began in August last year, the virus has infected about 2000 people, and caused 1400 deaths. Last week, a case

was confirmed across the border, in Uganda. Ebola starts with similar symptoms to the flu – fever and chills, muscle pain and headache – but it often ends in internal and external bleeding, and death. The largest outbreak killed more than 11,000 people in West Africa between 2013 and 2016. However, such epidemics are relatively unlikely because Ebola doesn’t necessarily spread between many people each time it “spills over” into the human population from bats or other

1400

people have died so far in the current Ebola outbreak

83 per cent (PLoS Neglected Tropical Diseases, doi.org/c7bq). Single cases are likely to be the most common outbreak size, but only two countries have reported these so far, they say. Ian Mackay at the University of Queensland in Australia says identifying outbreaks early when only a few people have been infected is vital, because it is easier and cheaper to contain them before dozens of people have been infected. He says the study also sheds light on curious trends that virologists have noticed in the decades since Ebola was discovered. “We have seen studies come out over the years from the 1980s onward showing indications that some people have antibodies [to the virus], but we haven’t seen that to be a part of ongoing outbreaks,” says Mackay. This could be explained by small outbreaks of Ebola going unreported. “If we’re seeing half or even up to 80 per cent [of spillover events] are missed, that might contribute to these strange antibody results,” Mackay says. ❚

A robot is using irony and now people like it more MEET Irony Man. This 30-centimetre-high robot combines nonchalant facial expressions with deadpan delivery in a way its inventors hope will make it seem more natural. By using irony in its dialogue, they say it could be used to break bad news gently and persuade people to do things they otherwise wouldn’t do. “Think of a robot in the role of a lifestyle adviser that feels the user 14 | New Scientist | 22 June 2019

should be more active and has to convey this message without appearing rude,” says Elisabeth André at the University of Augsburg, Germany, who worked on Irony Man. The technology is based on a computer program that analyses the best response the robot could make in a normal conversation. It then flips words and adds emphasis like overstatement to introduce irony, that is to say, when the intended meaning of a phrase is opposite to the literal meaning. So, in a conversation about the weather, the phrase “I hate raining. I usually have a bad mood when it

HCM-LAB, AUGSBURG UNIVERSITY

Machine learning Irony Man doesn’t know when ironic quips are inappropriate

rains” becomes “Super! I utterly love raining”, with elongated stress on the word “utterly” and a smile. In tests, a dozen students said they preferred conversations with Irony Man to those with a standard robot. They rated it consistently higher on qualities described as

likeable, appealing and motivating. The work was presented at the International Conference on Autonomous Agents and Multiagent Systems in Montreal. The next step is to find a way to make Irony Man bite its tongue. “The robot is not yet able to determine whether and when there is a good moment to employ irony,” André says. “It may happen that the robot generates a funny utterance, but the user is irritated.” Imagine the possibilities: Great! You put a totally expected item in the bagging area. Eye roll. ❚ David Adam

Analysis Food production

Physiology

Is vertical farming the way to a greener life? Crops grown under lights in racks are said to be environmentally friendly, but their eco credentials are unclear, finds Adam Vaughan

Strange fat cells in our bones don’t act like fat as we know it Michael Le Page

HOLLY L. CHALLINOR/ JONES FOOD COMPANY

LED lights let plants grow inside all year round

THE herbs in your future online supermarket delivery may be grown not in a field in a distant country, but in a shed on the outskirts of a nearby city. Last week, UK online supermarket Ocado invested £17 million in vertical farming, an industry that advocates say can produce food in a more environmentally friendly way. So will the investment allow Ocado to deliver greener fare? Ocado has taken a majority stake in Jones Food, which runs Europe’s biggest vertical farm on an industrial estate in Scunthorpe, UK. It has also invested in a joint venture with a further two firms involved in vertical farming: Priva, based in the Netherlands, and 80 Acres in Ohio. Vertical farming involves growing crops indoors under lights, in racks several metres tall. The technology expands crop production upwards and so requires less land. It also means that crops can be grown closer to where they will be consumed. That partly explains its success

in Asia, with commercial vertical farming in Japan dating back more than 15 years. The sector has a much younger history in Europe, emerging over the past five years. In Scunthorpe, basil and other herbs, watercress and leafy salad are grown in water under LED lights on racking that would collectively cover about 5000 square metres. “There’s always been an energy and employee argument which has probably held back vertical farming over the past decade,” says James Lloyd-Jones of Jones Food. The efficient nature of LEDs has been key to addressing that, along with lower-energy lighting that just emits the blue and red wavelengths that plants can use. Fertiliser use – farming’s traditional big energy burden – is “phenomenally reduced”, says Lloyd-Jones. Pesticide use is zero because few insects make it into the indoor environment. The labour-intensive nature of vertical farming has been tackled using automation, to a degree,

More analysis online Cloud gaming’s energy footprint newscientist.com/cloud-gaming

with just five of the company’s eight staff running the farm at any one time. Other firms in the UK are pursuing similar approaches. Stewart McGuire of Ocado, which has pioneered the use of robots for packing groceries, says the company wants to increase automation, be more efficient with lighting and grow a wider variety of crops – probably beginning with tomatoes, cucumbers and berries. He says issues with outsourcing food growth to other countries – “issues around deforestation, or mega-farm impacts or carbon emissions” – will favour local production in vertical farms. Do the green claims stand up? Some studies suggest not: one US researcher has calculated that the electricity bills associated with vertical farming may translate into hefty carbon footprints that effectively wipe out “food miles” savings from growing locally. “I think there’s a lot of hype about it,” says Tim Lang at City, University of London. “[Vertical farms] are more possible, more feasible because of LEDs, but they are still energy intensive.” He thinks conventional greenhouses, perhaps on city rooftops, are a better way of bringing food production closer to demand. Vertical farming could hold some environmental benefits, says Duncan Cameron at the University of Sheffield, UK, because it requires much less fertiliser. Food waste is also “reduced hugely”, he says, because of the “just-in-time” nature of indoor farms. But Cameron says vertical farming involves huge amounts of water and electricity. “We need to be cautious about the sustainability claims,” he says. ❚

THERE is a distinct type of fat in our bones that behaves differently from any other. These peculiar fat cells, or adipocytes, grow larger, not smaller, when we starve – and now we know they produce different proteins too. The main function of fat is to store energy and release it when needed, says Catherine Muller at the University of Toulouse, France. This is what most of the “white fat” in our bodies – found under our skin and around internal organs – does. We have suspected for a few decades that some of the fat cells inside our bone marrow may be different. Animal studies showed these cells grow bigger when animals starve, even though fat cells usually release energy and shrink in such circumstances. Now, Muller and her team have discovered something else unusual. They analysed samples of bone marrow fat and below-skin fat from people undergoing hip surgery, and found the bone marrow fat cells produce a distinctive set of proteins. This means they have a different metabolic role to white fat and should be regarded as a distant subtype, the researchers conclude. They propose calling them “yellow adipocytes”, or yellow fat (bioRxriv, doi.org/c7bd). Bone marrow fat should indeed be regarded as a different type of fat, says William Cawthorn at the University of Edinburgh, UK. Some of his research suggests the benefits of a calorie-restricted diet may be linked to a hormone produced by the cells - although he thinks it is confusing to give them a new name. What isn’t clear is why yellow fat behaves in such an odd way. It may play such a vital role in the production of blood cells in bone marrow that the body can’t afford to use it as an energy source during lean times, Muller says. This might explain why the cells don’t shrink when we starve. ❚ 22 June 2019 | New Scientist | 15

It will take humans nine months to get to Mars The biggest danger on the way? Boredom

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News In brief Solar system

Europa’s hidden ocean may be briny and ripe for life

NASA/JPL/DLR

HOPES of one day finding living things on Jupiter’s moon Europa have been given a boost. Sodium chloride, or table salt, spotted on its surface could mean that its buried ocean has a composition similar to seas on Earth and so is good for life. We have known for a long time that Europa has salts on its surface, but early observations suggested they were sulphates resulting from interactions between sulphuric acid and other compounds. Samantha Trumbo at the California Institute of Technology and her colleagues used the Hubble Space Telescope to examine the icy moon’s surface chemistry. They found signs of sodium chloride turning the surface yellow as it was hit with radiation from space. The strongest of these signals came from Tara Regio, a part of Mental health

CLOCKING up at least 2 hours a week in green spaces such as parks and woodlands is enough to improve health and happiness. The benefits of being out in nature have been welldocumented, but until now no one has quantified how much time might be beneficial. Mathew White at the University of Exeter, UK, and his colleagues came up with the 2-hour minimum by analysing a survey of 20,000 people in England, who reported how long they spent in natural environments in the past week, plus their health and well-being. People who spent less than 2 hours in nature were no more likely to report good health or well-being than those who spent no time there at all. Those who spent more than that had consistently higher health and well-being levels, although above 18 | New Scientist | 22 June 2019

Recycling

2 hours, the benefits seem to give diminishing returns. No further gain in well-being was detected after 5 hours. This could be because such times are clocked up by dog walkers who have little choice in the matter, says White. He says spending 2 hours in nature can be spread over a week. This should be possible for most people: the average person already clocks up 94 minutes a week. The team controlled for the fact that the health benefits might be a byproduct of physical activity, not contact with nature. The magnitude of the benefit of the 2 hours seems to be significant, on a par with the health differences associated between living in a well-off area and a deprived one. The benefits seem to apply to everyone, regardless of age, gender, long-term illness or disability (Scientific Reports, doi.org/c69k). “You don’t have to be running around the park, just sitting on a bench will do,” says White. Adam Vaughan

Solution to snack waste is in the bag A NEW kind of wrapping could soon solve the problem of crisp packet waste. When people started posting their packets back to crisp manufacturer Walkers to protest that they weren’t easily recycled, the firm took notice and launched collection points for them. But this special scheme has recovered just 3 million of the 4 billion bags the company sells annually in the UK,

JACK SULLIVAN/ALAMY

A regular visit to the park is good for you

the moon thought to be shaped by water seeping up from the subsurface ocean. That indicates that the salt could be coming from within Europa, hinting at the ocean’s chemical composition (Science Advances, doi.org/c677). We have never actually detected an ocean with primarily sulphates for salts, says Trumbo. “If it’s sodium chloride instead, that means it’s more like Earth. If you licked it, it would probably taste familiar.” That is a good sign, in terms of looking for life. Earth’s oceans are the only ones in the universe that we know to be habitable. The subsurface ocean of Saturn’s moon Enceladus has many of the necessary ingredients for life, such as complex organic molecules, and is also full of sodium chloride. Leah Crane

and they still aren’t accepted by household recycling schemes. The root of the problem is that the metallised films used for packaging crisps and many other foods are great for keeping contents dry and cool, but hard to recycle. Now Dermot O’Hare at the University of Oxford and his team have come up with an alternative. It is a thin layer, called a nanosheet, made from amino acids and water. This is applied to a film of PET, the plastic used to make most water bottles. The nanosheet’s benign building blocks appear to result in a material safe for use with food and that can be widely recycled, says O’Hare. Crucially for such packaging, it is a good barrier to gases and survives crumpling. But O’Hare says that a long regulatory process means it will be at least four years before the material reaches shop shelves (Nature Communications, doi.org/c679). AV

New Scientist Daily Get the latest scientific discoveries in your inbox newscientist.com/sign-up Ancient settlements

Really brief

British ‘Pompeii’ rose and fell in just a year

XINHUA/PA

NEARLY 3000 years ago, fire swept through a settlement of wooden dwellings built on stilts in the marshy Fens of eastern England. The buildings, which collapsed into the silt below, were only rediscovered in 1999. Dubbed the UK’s Pompeii, the very well-preserved site gives an unprecedented glimpse of daily life in the late Bronze Age. The silt preserved not only the structure but also the everyday items not

Hatched and ready to hunt An analysis of 37 fossilised pterosaur eggs found in Jinzhou, China, in 2017 suggests that the winged reptiles may have broken out of their eggs with their wings fully formed and ready to fly (Proceedings of the Royal Society B, doi.org/c697).

usually found in the prehistoric archaeological record, including 180 textile items, the remains of food in pots and faeces. To find out how long the settlement existed, Mark Knight at the University of Cambridge and his colleagues pieced together strands of evidence. Analysis of the tree rings from the timbers showed they were fresh. Wood chips from the construction of the buildings were found around the site, but very little detritus from human occupation. The absence of wood-boring insects and fleas indicates that

Archaeology

Education

Minority children get more noise pollution

Gene editing gets another upgrade Two teams have used similar approaches to develop new versions of the CRISPR gene-editing system. Unlike existing methods, these upgrades could enable researchers to insert specific sequences of DNA wherever they want in the genome. Both are based on transposons: genes that can jump to new locations (Science, doi.org/c7bb; Nature, doi.org/c7bc).

XINHUA WU

Parkinson’s treatment The main drug used by millions of people with Parkinson’s disease levodopa - is made less effective by microbes and enzymes that break it down in the body. But a molecule has been found that can block this degradation in mice (Science, doi.org/c699).

there hadn’t been time for these animals to colonise the buildings. Together, the evidence indicates the site existed for a year, perhaps even less (Antiquity, doi.org/c69r). No one seems to have died in the fire. “We half expected to find bodies underneath the roof. That really would have been a Pompeii moment,” says Knight. The settlement could have been torched by rivals or the occupants could have instigated the fire themselves, says Knight. “They could have torched it themselves in some grand gesture.” Alison George

People were getting high on pot at least 2500 years ago THE “earliest unequivocal evidence” of the use of cannabis as a drug has been found in tombs dating to around 500 BC. Telltale chemical traces were discovered at the Jirzankal Cemetery site in China. This psychoactive cannabis was probably used in funeral rites. Hot pebbles would have been placed in a wooden brazier (pictured above) and cannabis put on the stones. An analysis of the brazier wood and stones by Yimin Yang at the University of Chinese Academy of Sciences in Beijing and his team found traces of cannabidiol (CBD) and cannabinol. THC, the chemical in cannabis that makes people high,

breaks down into cannabinol when exposed to air or light. Wild cannabis has low levels of THC and would leave traces with similar amounts of cannabinol and CBD, says Yang. He found much higher levels of cannabinol than CBD. That shows people had mutant strains of cannabis richer in THC (Science Advances, doi.org/c68v). Such cannabis use was recalled by Greek historian Herodotus in around 440 BC: “The Scythians… throw it upon red-hot stones; immediately it smokes, and gives out such a vapour as no Grecian vapour-bath can exceed; the Scyths, delighted, shout for joy.” Michael Le Page

US SCHOOLCHILDREN from ethnic minority or poorer backgrounds are much more likely to be exposed to noise pollution from cars and planes. While white pupils make up around half of the country’s 50 million pupils, only 35 per cent of those exposed to high levels of traffic noise are white, Timothy Collins at the University of Utah and his colleagues found. Hispanic children make up 26 per cent of school age students, but 36 per cent of the children affected. Black youngsters are 16 per cent of the school roll, but 20 per cent of those highly exposed to noise. Children on free or reduced-cost school meals, a proxy for poverty, make up 51 per cent of students, but 59 per cent of those hit by noise pollution. Collins and his team made the findings by overlaying the locations of primary and secondary schools, complete with data on their demographics, with a US government noise-mapping tool. (Environmental Research, doi.org/c69). Noisy environments have previously been linked to worse academic performance. Schools should look to address the imbalance by soundproofing buildings, says Collins. AV 22 June 2019 | New Scientist | 19

News Insight Activism

Do protests work?

20 | New Scientist | 22 June 2019

Large crowds protested extradition plans in Hong Kong on 12 June

36 m Number of people who marched against the 2003 invasion of Iraq

ERIK MCGREGOR/GETTY IMAGES

HUNDREDS of thousands of people filled the streets of Hong Kong on 9 June to protest a government plan to allow extraditions to mainland China. The demonstrations have continued regularly since, with seas of protesters surrounding a government building and preventing law-makers from meeting about the proposed law. Hong Kong’s chief executive, Carrie Lam, has suspended the bill, but protesters say this doesn’t go far enough and want the law to be scrapped. As New Scientist went to press, it was unclear if this demand would be met. The approach in Hong Kong is just one of many ways protesters have recently been attempting to challenge the status quo. Tactics range from marches to violent civil disobedience, but it can be difficult to tell what, if any of it, really works when it comes to effecting change. The result can depend on the type of protest. Matthew Feinberg at the University of Toronto and his colleagues have found that peaceful protests like sit-ins and marches can amplify a message and draw new supporters, but that extreme or violent tactics backfire, putting people off from supporting their cause. “The easiest way to become known is to get the news to cover your movement, and the easiest way to do that is by doing something extreme. But it’s a catch-22,” says Feinberg. One way to bring attention to a cause is to disrupt the hum of normal life. In April, climate protesters Extinction Rebellion had success with this method, bringing some transport hubs in central London to a standstill by blocking the streets with people and gluing themselves to trains. The movement quickly gained

ANTHONY KWAN/GETTY IMAGES

People around the world are taking to the streets, but what do mass demonstrations achieve? Chelsea Whyte investigates

Thousands of women celebrated the 2017 Women’s March in New York this January

attention from the press and attracted new supporters, partly thanks to social media. But it also drew criticism from people who felt the inconvenience didn’t justify the cause. In a series of studies, Feinberg and his team delved into the trade-off that protest groups have to make. They presented people with news articles and videos of protests and found that extreme actions – including forming blockades, rioting, damaging property and violence – meant people supported and identified with the protesters less. This was true even if they believed in the group’s goals. This may be because people value actions they perceive as reasonable, and most people identify themselves as reasonable, so extreme protest tactics make it

harder to identify with activists, says Feinberg. However, even protests that aren’t extreme may be perceived as being so by people who disagree with the aims. In another study, Feinberg and his colleagues showed people videos from the 2017 Women’s March. This rallied 500,000 people in Washington DC and 2.5 million more in cities around the world to advocate for civil rights in the wake of Donald Trump’s election. It was largely peaceful, which helped correct the mistaken impression many have that protest is always violent, says Eden Hennessey at Wilfrid Laurier University in Ontario, Canada, who worked on the study. “We all saw that it wasn’t people holding Molotov cocktails with bandannas over their face. It was Sharon from down the street,” she says. The team showed people videos from the march that included benign actions like women chanting or high-fiving. They then asked viewers how many people were breaking windows, burning things or engaging in fights. Even though these things weren’t in the videos, nearly 8 per cent of people responded that they had seen such violence – and these people all identified as Trump supporters. “Our data would suggest that, depending on your political views, you’re going to interpret information differently,” says Hennessey. In other words, some people will see what they want to see, if they are sufficiently opposed to the cause. But recruiting more supporters is only one aim for protest movements. Can they change policy too? It is clear that not all protests work. It is estimated that more than 36 million people across the world marched against the 2003

Working hypothesis

More Insight online Your guide to a rapidly changing world newscientist.com/insight

VICTOR DE SCHWANBERG/ALAMY STOCK PHOTO

Extinction Rebellion protests have disrupted London in recent months

protests in their districts. Larger protests correlated with higher turnout at subsequent town hall meetings with congressional leaders, while smaller protests lowered the probability of a representative’s vote aligning with protesters’ demands by 8.7 per cent. And every Tea Party protester

“It wasn’t people with Molotov cocktails and bandannas. It was Sharon from down the street” in a district was related to an increase of between seven and 15 Republican voters in the area. The sustained Tea Party protests also led to more media coverage of the movement and its aims to limit government spending, and added members and financial contributions to the movement. It wasn’t fully successful, however. When it came to major national legislation, such as the Affordable Care Act (ACA) healthcare bill that was so vehemently opposed by the Tea Party that the movement’s proponents in Congress shut down the government over it, the protesters didn’t achieve their

goal. The bill became law in March 2010 and still stands today. Veuger says the effects of protest may be more local, or more diffuse. “The ACA passed before the first election in the fall of 2010 in which the Tea Party could have an impact. But they were still successful. Nothing along those lines has passed after the 2010 midterms,” he says. The effects of protest can also hit policy-makers where it hurts: the economy. Daron Acemoglu at the Massachusetts Institute of Technology and his colleagues looked at how the Egyptian stock market was affected by the mass demonstrations in Tahrir Square in Cairo in 2011, which ended with the resignation of president Hosni Mubarak. The team analysed stock returns of 177 firms listed on the Egyptian stock exchange between 2005 and 2013 and found that more protesters in the streets led to lower market valuations for those firms whose shareholders and board members were connected to the National Democratic Party, the party of Mubarak. A turnout of 500,000 protesters in Tahrir Square was correlated with a 0.8 per cent lower valuation in those companies than the firms unaffiliated with members of the political party in power. Economic pressure can affect policy-makers and the same goes for social change. For example, although the Women’s March suffered from not having specific policy goals, that doesn’t mean it wasn’t successful, says Hennessey. After January 2017, the MeToo movement to bring to light and end sexual violence really took hold. “I don’t think the MeToo movement would have gained traction in the same way without it. You need a crack and then the water starts to seep in,” she says. ❚

▲ Tiny bagels Spare a thought for those brunching in the Bronze Age. Archaeologists have found what seem to be 3000-year-old bagels. You’d need a lot – they are just 3 centimetres across. ▲ Space oddity It is one giant leap for DJs. Luca Parmitano is due to perform the first DJ set from space in August from the International Space Station. ▼ Fake CEOs A video of Facebook’s Mark Zuckerberg speaking with the emotion of a robot has appeared online. Yes, we were surprised it was an AI-generated fake too. ▼ Face control Your face could soon be your passport. But if data breaches occur, like the US one last week, you may need to get a new face… ▼ Blood crystals RIGHT: STUART PITKIN/GETTY; TOP: WUJUN MA, MURDOCH UNIVERSITY

invasion of Iraq, yet it still went ahead. Although the marches rallied people to the cause, they ultimately failed to change the policy the movement opposed. Still, protests do sometimes appear to directly affect policy, as a case study of the Tea Party movement in the US found. In April 2009, there were a series of rallies that began with hundreds of thousands of people gathering in US cities to protest against spending by the Obama administration. That was followed by rallies throughout the following spring and summer targeting local taxes and budgeting decisions. According to Stan Veuger at the American Enterprise Institute, they were successful. He and his colleagues analysed the sizes of these protests and measured related changes in voting patterns and policy change by comparing the way members of Congress voted before and after the protests. They found that members of Congress were more likely to vote conservatively – in line with Tea Party principles – after large

Sorting the week’s supernovae from the absolute zeros

It is a new age for the new age. Healing crystals are having a revival, but mining them is bad news for the planet.

22 June 2019 | New Scientist | 21

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UK National Space Centre Director Anu Ojha The Apollo moon landings: conspiracy theories and critical thinking skills in a post-truth world. What’s the role of science in a world LQFUHDVLQJO\LQćXHQFHGE\GLVWRUWLRQ spin and disinformation?

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Comment

Don’t dismiss ‘anti-vax’ To win over opponents of vaccination, we must understand the often complex roots of their mistrust, says Furaha Asani

JOSIE FORD

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EASLES is making a shocking return to the US. At the heart of this return is a growing reluctance by some groups in society, fanned by social media, to have their children vaccinated, citing mistrust of government, big pharma and scientists in pushing inoculation. It is easy to dismiss “antivaxxers” as just misinformed and misguided. But vaccine mistrust isn’t monolithic. To fully and respectfully engage with people, the reasoning behind different communities’ doubts must be unpacked with nuance. An instructive perspective comes from elsewhere in the world. While the World Health Organization reports that vaccine uptake is increasing globally,

60 per cent of children who didn’t receive routine immunisations in 2017 came from just 10 countries in Asia and Africa. A deep-rooted mistrust of Western health interventions is one cause. Take the malaria vaccine RTS,S, which GlaxoSmithKline rolled out as part of a pilot study in Malawi earlier this year, with Ghana and Kenya set to follow. RTS,S is up to 40 per cent effective at preventing malaria in young children. Not great, but this is the first proven vaccine against a disease that kills 1200 people a day worldwide, most of them children in Africa. Yet the trial has provoked a backlash, with concerns ranging from Africans being used as guinea pigs in an unethical trial to it being a plot to sterilise local populations.

Social anthropologist Ayodele Samuel Jegede of Ibadan University in Nigeria studied the roots of a polio vaccine boycott in northern Nigeria in the early 2000s. He showed how it was influenced by the Trovan case, in which the drugs company Pfizer was accused of unethically trialling an antibiotic against meningococcal meningitis in the region in the 1990s. Pfizer denies the claims, and settled a case brought by the Kano state government out of court for $75 million in 2009. The theme that vaccines are a ploy for sterilisation has been seen in Cameroon, Tanzania, Pakistan, Afghanistan and India. It has its roots in fear of eugenics. With eugenicist programmes

conducted as recently as the 20th century in the US, this fear hits close to home – perhaps one reason why African Americans register lower uptake of certain vaccines. Jegede’s study describes how vaccine boycotts can be avoided through engagement with community leaders, local public awareness campaigns and locally based ethics committees to help ensure that interventions take into account cultural norms and sensibilities. A meta-study of 14 vaccination interventions in developing countries conducted in 2011 by Angela Oyo-Ita at the University of Calabar Teaching Hospital in Nigeria and her colleagues supports the idea that such initiatives can boost uptake. In the US, the College of Physicians of Philadelphia also emphasises the importance of communication and respect for diverse social and cultural perspectives in building trust around vaccines. Appropriate action needs to be taken to maximise vaccine take up. But that involves engaging with the roots of mistrust – and understanding that the practice of science itself may carry some blame. Collectively and pejoratively labelling those opposing vaccination as “antivaxxers” won’t solve anything. ❚

Furaha Asani is at the University of Leicester, UK. Follow her on Twitter @DrFuraha_Asani 22 June 2019 | New Scientist | 23

Views Columnist No planet B

A question of faith Climate change threatens biblical floods and famine. Will religion ultimately help or hinder the battle to stem the disasters, wonders Graham Lawton

I

Graham Lawton is a staff writer at New Scientist and author of The Origin of (Almost) Everything. You can follow him @grahamlawton

Graham’s week What are you reading? I’ve just finished The Emigrants by W.G.Sebald, one of my favourite authors. He wrote unconventional, moving books exploring themes of loss and displacement.

What are you working on? I’m scrambling to wrap up the manuscript for the next New Scientist book, on diet and fitness. My own diet and fitness regimes are suffering…

This column will appear monthly. Up next week: Annalee Newitz 24 | New Scientist | 22 June 2019

GIUSEPPE CICCIA/PACIFIC PRESS/LIGHTROCKET VIA GETTY IMAGES

What are you watching? Killing Eve and The Handmaid’s Tale. But I’m mostly listening to a podcast series called It Could Happen Here, discussing whether the US is heading for a second civil war.

N 2011, when the Republican party took back the US House of Representatives from the Democrats, one of its first actions was to get rid of environmentally friendly crockery in the cafeterias there and bring back good ol’ plastic. The Republicans insisted that the eco cups and cutlery weren’t biodegradable and cost too much, but the subtext was clear: screw the environment, and all who sail in her. I retell this anecdote not to rake over old coals, but to suggest that you can tell a lot about an organisation’s environmental commitment by looking at its catering operation. Judging from the cutlery at the Pontifical Gregorian University in Rome, the Vatican still has a long way to go. At first glance, the knives, forks and spoons look like metal. But they turn out to be metal-coated plastic. Non-recyclable, metalcoated plastic. One use, and they are off to landfill purgatory. I was there for a conference on non-religious belief (yes, at a university administered by the Vatican!), but unexpectedly ended up hearing a lot about the environment. It turns out that secularism, religion and environmentalism are entwined in ways that have scarcely been explored, yet will become more important as the environmental crisis gathers pace. Shortly before the minor political tremor over tableware in Congress, a real earthquake struck Christchurch in New Zealand. It caused widespread destruction and killed 185 people. There was an unexpected aftershock. New Zealand is one of the world’s least religious countries, but after the quake, attendance at religious services rose dramatically and stayed high for months. This is taken as good evidence of

the “existential threat” hypothesis of belief, which holds that where life is more precarious, people increasingly turn to religion. One little-explored effect of climate disaster – which pretty much defines the concept of an existential threat – is what it will do to religiosity. Given what we already know about quakes and other natural disasters, I would bet good money on it driving people into the arms of God. In other words, what the major world religions teach about environmental issues will become increasingly important. And from what I heard in Rome, I am not

“I’d bet good money on the threat of climate change driving people into the arms of God”

confident that they will be helpful. The Catholic church looks quite green. But like its cutlery, appearances can be deceptive. In 2015, Pope Francis issued an encyclical on the environment. For those (like me) unfamiliar with Vatican terminology, that is a bit like a memo from head office informing regional managers about the boss’s latest thinking. It isn’t an instruction, but is guidance that you are well advised to heed. The encyclical called for rapid action on environmental destruction and biodiversity loss, which enraptured some environmentalists. The Catholic

church has 1.3 billion followers worldwide. They don’t hang on the Pope’s every word, but he is still influential. However, there are reasons to regard the encyclical with scepticism. For one thing, it said nothing about birth control, which the church opposes, and hence the topic of my last column, population growth. The encyclical also seems to have been quickly forgotten. In Rome, I asked a young, devout theology student from the Philippines whether it had made an impact on the church’s teachings or the attitudes of its followers. Not a bit, he said. There is a more fundamental reason to be suspicious. According to Lori Beaman, professor of religious diversity and social change at the University of Ottawa in Canada, the encyclical remains steeped in the Christian tradition of stewardship, which holds that God entrusted humans to take care of Earth but will heal whatever damage we do. In the past, this has been interpreted as divine consent to rape and pillage the planet as we see fit. Of course, the Catholic church may be absolutely sincere. If so, it needs to up its game and start preaching the message. And it isn’t the only faith in town. How other religions respond to environmental breakdown matter just as much. There are some positive signs: there was a strong religious presence at Extinction Rebellion’s recent climate protests. Like many other progressive, secular environmentalists, I am deeply conflicted about getting into bed with religion. But as we descend into a climate and biodiversity crisis, we are going to need all the help we can get. There is probably no God, but if there is, it would be better if He was on our side. ❚

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Views Your letters There are more ways to profit from going green 25 May, p 5 From Liam O’Keeffe, Abinger Hammer, Surrey, UK While I agree with your leader about the political response to global warming, I believe that you are too pessimistic when you say that “dealing with climate change comes with a cost”. On the contrary, making the transition to renewable energy is a natural investment. As the price of energy storage comes down, the marginal cost of renewable energy generation is falling to zero, since wind, sun and waves are free resources. This is in sharp contrast to hydrocarbon fuels that must be extracted at great cost. Countries that continue to invest in hydrocarbon resources are saddling themselves with technology that will soon be obsolete and unable to compete directly with renewable energy. Those that lead the way with renewables will enjoy a competitive advantage in global markets. For once, greed is good!

How long till we reach peak population? 25 May, p 24 From Paul McKinley, Dublin, Ireland I am not sure why Graham Lawton thinks population growth is a taboo subject. I have recently read three books that discuss it and it would seem overpopulation is a battle that is mostly won. A great deal of the world already has a fertility rate at, or below, replacement level. Even in those parts of the world where birth rates are higher, graphs of fertility over the past 30 to 50 years show a sharp decline. Industrialisation, urbanisation and especially education are drivers of population decline and there is no reason to suppose those declines won’t continue. Hans Rosling at the Gapminder Foundation thought the year of “peak child” was 2000. In 26 | New Scientist | 22 June 2019

Enlightenment Now: The case for reason, science, humanism and progress, Steven Pinker examines how the fertility decline that took Europe 200 years was reached by the developing world in just two generations. In Empty Planet: The shock of global population decline, authors Darrell Bricker and John Ibbitson make a strong case that the human population will peak at around 9 billion in 20 to 30 years, then decline. It may be that the fear of too many people will soon be replaced (as it already has been in Japan and Singapore) with a fear of too few: not enough tax payers to support a greying population and not enough young consumers to drive an economy.

Age is just a number, unless you’re giving blood 8 June, p 7 From Richard Lucas, Camberley, Surrey, UK Ruby Prosser Scully continues a story that has rumbled through the pages of New Scientist for the past couple of years, lending hope that ageing could be delayed by transfusions of young blood.

Having been a regular blood donor for 45 years, I observe that the majority of donors are, like myself, older. The likelihood is that the donated blood will find its way into a younger recipient, presumably having the opposite effect to young blood. Has this been thought through? Should donated blood be “age stamped”?

Weighty theories on the matchbox illusion 25 May, p 13 From Michael Jessop, Stratford-upon-Avon, Warwickshire, UK You report an illusion whereby three matchboxes together appear to be lighter than the heaviest box on its own. I believe this error occurs because we are comparing the weight of the heaviest box not to the total weight of all three, but to the average weight of them. We can’t compare grouped items directly. Instead, we must identify differences by comparing individual items with the group average. For example, we identify the heaviest of the boxes because it is the one that feels heavier than the average of the three, not

because we compare the weights of the individual boxes. Similarly, suppose you look at a black square that is beside a white square. The black square appears darker than the white one, not because you are comparing the two squares, but because the black square is darker than the average of the two, which is grey. From Thomas Patrick Reid, Dundee, UK I have a couple of observations following your article on the matchbox illusion. First, an item of flat pack furniture seems to be far less heavy once assembled. Second, when the head of a pint of Guinness settles, it appears to have gained weight. Could an object’s density fool our perception of its weight?

Which countries take part in nuclear inspections? 18 May, p 11 From David J. Plews, Rotherham, South Yorkshire, UK I commend Debora MacKenzie’s article about Iran’s nuclear programme, which points out the unintended consequences

of US president Donald Trump’s withdrawal from the 2015 Joint Comprehensive Plan of Action nuclear agreement. However, I was surprised at the line: “the standard inspections the IAEA does in all countries with nuclear plants”. I thought that the IAEA had been refused access to nuclear facilities in Israel, India, Pakistan and North Korea? The editor writes: ❚ Perhaps strictly we should have said: “in all member countries with nuclear plants”. The countries mentioned aren’t members of the IAEA and haven’t signed the nuclear non-proliferation treaty, or have signed and left in the case of North Korea. The general inspections obligation applies to all states that have signed the treaty apart from the recognised nuclear weapons states (the P5), although the P5 have agreements with the IAEA whereby their civil nuclear plants are inspected as a courtesy.

Carbon tax must come with carbon dividends 25 May, p 23 From Gareth Ackland, London, UK I commend your article on the European Parliamentary elections for flagging up the fear of higher environmental taxes, which could only make life disproportionately harder for poorer people. It may fuel populism and encourage the idea that environmentalists are part of an elite. The carbon fee and dividend scheme championed by climate scientist James Hansen accounts for this, and, indeed, inverts it: all levies raised from extraction or import are divided equally between citizens. The dividend for someone on a low income would easily outweigh the price increases to their weekly shop. A high earner

who overconsumes would be penalised and hopefully given incentive to adapt. Hard for a populist to argue against a scheme that makes those who are profiting less from society richer.

A world without rubber might not be so bad 18 May, p 44 From Euan Connell, Aberdeen, UK I just read your feature about Earth’s rubber supply. As someone with allergies to latex and the accelerators used in rubber production (carba mix and thiuram mix), the prospect of a world without rubber seems fantastic. I think this should serve as a wake-up call that we have, yet again, become too dependent on a finite resource and alternatives should be considered. My view may be biased, but I don’t think it is unjust. The rubber particles end up in our atmosphere and it could be contributing to the rise in allergies. Pollution is never a good thing.

We have to change if we want to make it in space 18 May, p 5 From Julius Wroblewski, Vancouver, British Columbia, Canada Your leader about the new space age made me think back to all the starry-eyed dreams of space travel I had as a child, watching space missions and sci-fi programmes on TV. Where is the vacation on the moon that I was promised? Where is the HAL 9000 from 2001: A Space Odyssey that I should be using and fearing? We have great gadgets, to be sure, but they are about as sentient as a toaster. Crewed space travel has turned out to be far more expensive and dangerous than I imagined as a

Want to get in touch? Send letters to New Scientist, 25 Bedford Street, London WC2E 9ES or [email protected]; see terms at newscientist.com/letters

child. Is it necessary? Wouldn’t it be great if robots could do the dangerous work instead? I hope to see the day when humans won’t need to go down mine shafts to extract minerals, likewise for the worst bits of space travel. Then again, venturing into space will eventually become vital. Mother Nature has placed us in a trap: a presently fertile world that will eventually be rendered uninhabitable by a bloated red giant star. If we are to make the transition, we will have to alter our genome to cope, creating Homo spatialis, able to handle radiation and microgravity without collapsing into a heap.

for ostensibly the same inputs. The final output of a mind that creates the actions of a “free agent” may be expected to have a complex relationship to the prior states and external stimuli that produced it. Indeed, it is probable that elements of the end state act through feedback mechanisms on their prior states, before coalescing into their final form. The complexity of such a highly nonlinear process in the brain may be almost impossible to model comprehensively, but it can be represented by mathematics, even if the state information and details of the interactions will always elude us.

AI’s countless failings foretold in fiction

From Neil Doherty, Wilthorpe, South Yorkshire, UK Continuing the debate on free will that regularly features in New Scientist these days, I am concerned that the scientific costs of this discourse are rising exponentially as more scientists pick a side. I realise that doing science also requires discussion, so that we might progress by such means as well as through experiment and empirical observation. None of these methods can check free will via the scientific method. The costs of discussing an unprovable conjecture like the existence of free will are wasted “science”. If one can’t present serious evidence beyond the work of the mind alone, then one can’t prove the speculation, no matter how long the discussion lasts. Scientists need to consider how much research time they are wasting on this topic, then get on with properly testable science and leave free will to the philosophers.

13 April, p 12 From Nick Goddard, Manchester, UK So Deepmind’s artificial intelligence can’t add up. That reminds me of the late, great Stanislaw Lem, who foresaw this more than 50 years ago in his short story Trurl’s Machine. The eponymous inventor creates an eight-storey thinking machine that, when asked to calculate two plus two, thinks for a while and replies “seven”. At least Deepmind’s AI didn’t try to kill its creators – unlike Trurl’s machine.

Free will is complicated, let’s leave it at that Letters, 25 May From Neil Higgins, Abingdon, Oxfordshire, UK I would like to challenge the view of mathematics presented in Peter Bennett’s letter on the topic of free will. He seems to think that mathematics can only deal with problems that can be described in either a simplistic deterministic way or as the result of entirely random events. He is therefore incapable of describing phenomena where hysteresis is involved, a feature that would seem essential if free will implies that different outcomes can occur

Different verbs for different celestial bodies 25 May, p 16 From Andrew Glassner, Seattle, Washington, US I read your headline “Chinese rover unearths moon’s deeper secrets”, and I suspect we are being trolled. Surely the proper verb would be “unmoons”.  ❚ 22 June 2019 | New Scientist | 27

Views Aperture

28 | New Scientist | 22 June 2019

Like wildlife photography? Visit the Incredible Creatures Feature at New Scientist Live newscientistlive.com/incredible-creatures-feature

Don’t move… Photographer Chien C. Lee Agency Minden Pictures

IF YOU had to look twice, then the trick has worked. This common potoo (Nyctibius griseus) was spotted in Utría National Natural Park, Colombia, using its chief defence against predators: disguising itself as a branch. During the day, the bird perches motionless on a tree for long periods, with both parents taking turns to incubate a single egg. Their posture, plus their mottled brown and grey plumage, makes the perfect camouflage. As it is a nocturnal bird, the potoo has huge yellow eyes. In daylight, it must peer through narrow slits to watch out for potential threats so that its eyes don’t give the game away. At dusk, however, it transforms into a voracious hunter of moths and flying beetles. The common potoo is found in woodlands and savannah in Central and South America, although its habitat is in decline. In Peru, its haunting song, a mournful series of descending notes, is said to evoke a lost child calling for its mother.  ❚ Clare Wilson

22 June 2019 | New Scientist | 29

Views Culture

Sex, secrets and podcasts A challenging podcast about women’s sexual and reproductive health is set to change lives – and not just in India, says Sandrine Ceurstemont

Podcast

She Says She’s Fine BECOMING a mother is often portrayed as a magical experience where you instantly form a bond with your child. But author and journalist Meghna Pant, a guest on the motherhood episode of a new women’s sexual health podcast, explains that it took her a month to fall in love with her child. “Initially, it’s like an alien creature,” she says. Breastfeeding, too, doesn’t always come naturally. It can also be painful due to cracked nipples and inflamed or infected breast tissue, for example. “Nobody tells you what happens when your milk comes in,” says Kiran Manral, another author and guest on the show. “Suddenly you have stones on your chest, like boulders.” Even in 2019, people still feel shame when talking about certain aspects of women’s reproductive health. But host Munjaal Kapadia, a gynaecologist at Namaha Healthcare in Mumbai, India, is aiming to change that in a podcast called She Says She’s Fine. With 10 episodes so far, the show has tackled topics ranging from abusive relationships, using IVF, being gay and experiencing miscarriage. Guests share their experiences and struggles in an informal and conversational style, and myths are busted. Although the show addresses issues in the context of India, it is relevant globally. Miscarriage, for example, is common around the world, but speaking about it remains taboo. The process is typically beyond a woman’s control because it is often the result of chromosomal abnormalities. An episode on 30 | New Scientist | 22 June 2019

DAVID TALUKDAR/AFP/GETTY IMAGES

Produced by Maed in India

the topic highlights the feelings of guilt often experienced by women, who wonder whether stress, for example, could be the cause. The podcast brings men into the conversation, too. A couple talk about their experience with IVF, providing insight into details

“From pregnancy tests becoming available in many countries to IVF and egg freezing, this is radical change” of the process, emotions they each went through and ways of dealing with an unsuccessful outcome. The role of male partners is explored, in particular what their involvement should be given that a woman bears most of the physical brunt of the procedure. The message is that men need support as well. Kapadia also breaks down barriers between doctors and

patients. Women may feel uncomfortable seeing male gynaecologists or may avoid going to the doctor for sexual health issues as they fear embarrassment or being judged. But Kapadia’s relaxed manner and empathy puts listeners at ease. And he doesn’t hold back from sharing personal experiences, with him and his wife talking about their miscarriage, for example. A poignant moment exposes the complexity of experiencing a miscarriage as both a doctor and as a man. The power technology is giving women over their sexual and reproductive health is another strand explored by the podcast. From pregnancy tests becoming available in shops in most countries to IVF and egg freezing allowing women to have children later in life, this is radical change. Googling symptoms and health problems online also means people are more informed when they visit doctors. The downside is the difficulty

An Indian wall painting about menstruation raises awareness

in separating facts from fiction. Future seasons of the show will deal with controversial topics such as abortion and the science of female orgasms. Kapadia also wants to dive deeper into the topics he has already covered. The episode on periods, for example, triggered many questions from listeners about polycystic ovary syndrome , a condition that is common yet misunderstood. Being better informed about women’s reproduction should help overcome the feeling of being alone with a problem – a common theme that emerged from many of the show’s discussions. “We do a grave injustice to society by not talking,” says Kapadia. “The more women tell their stories, the more sensitive people will become.” ❚ Sandrine Ceurstemont is a science writer based in Morocco

Don’t miss

Dead but undying From Tinder messages to tragic memories, the digital afterlife of the dead matters in new and unexpected ways, finds Simon Ings

All the Ghosts in the Machine: Illusions of immortality in the digital age Elaine Kasket Little, Brown

MOVING first-hand interviews and unnervingly honest recollections weave through psychologist Elaine Kasket’s first mainstream book, All the Ghosts in the Machine, an anatomy of mourning in the digital age. Unravelling that architecture involves two distinct but complementary projects. The first offers some support and practical guidance for people (and especially family members) who are blindsided by the practical and legal absurdities generated when people die in the flesh, while leaving their digital selves very much alive. For some, the persistence of posthumous data, on Facebook, Instagram or some other corner of the social media landscape, is a source of “inestimable comfort”. For others, it brings “wracking emotional pain”. In neither case is it clear what actions are required, either to preserve, remove or manage that data. As a result, survivors usually oversee the profiles of the dead themselves – always assuming, of course, that they know their passwords. “In an effort to keep the profile ‘alive’ and to stay connected to their dead loved one,” Kasket writes, “a bereaved individual may essentially end up impersonating them.” It used to be the family who had privileged access to the dead, to their personal effects, writings and photographs. Families are, as Survivors usually end up managing the profiles of the dead themselves

the Machine opens with an account of the author’s attempt to rehabilitate her grandmother’s bitchy reputation by posting her love letters on Instagram. “I took a private correspondence that was not intended for me and transformed it from its original functions. I wanted it to challenge others’ ideas, and to affect their emotions... Ladies and gentlemen of today, I present to you the deep love my grandparents held for one another in 1945, ‘True romance’, heart emoticon.” Eventually, Kasket realised that the version of her grandmother her post had created was no more truthful than before. By then, of course, it was far too late. The digital persistence of the dead is probably a good thing in these dissociated times. A culture of continuing bonds with the dead is much to be preferred over one in which we are all expected to “get over it”. But, as Kasket observes, there is much work to do, for “the digital age has made continuing bonds easier and harder all at the same time.”  ❚

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The Weather Machine: How we see into the future (Bodley Head) is Andrew Blum’s account of the extraordinary, expensive yet oddly underappreciated infrastructure that makes modern weather forecasting possible.

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a consequence, disproportionately affected by the persistent failure of digital companies to distinguish between the dead and the living. Who has control over a dead person’s legacy? What unspoken needs are being trammelled when their treasured photographs evaporate or, conversely, when their salacious post-divorce Tinder messages are disgorged? Can an individual’s digital legacy even be recognised for what it is in a medium that can’t distinguish between life and death? Kasket’s other project is to explore this digital uncanny from a psychoanalytical perspective. Otherwise admirable 19th-century ideals of progress, hygiene and personal improvement have conned us into imagining that mourning is a more or less understood process of “letting go”. Kasket’s account of how this idea gained currency is a finely crafted comedy of intellectual errors. In fact, grief doesn’t come in stages, and our relationships with the dead last far longer than we like to imagine. All the Ghosts in

The Great Exhibition Road Festival between 28 and 30 June sees South Kensington in London channel the spirit of the Great Exhibition of 1851 to celebrate 200 years since the births of Queen Victoria and Prince Albert.

22 June 2019 | New Scientist | 31

Views Culture The TV column

Eyes wide shut Horror stalks the screen in different forms as the doomed Franklin expedition to find the North-West Passage and the Chernobyl nuclear reactor meltdown become terrifying docudramas. Chelsea Whyte feels the fear

All crew on the Franklin expedition died after getting stuck in Arctic ice

AMC

Chelsea Whyte is a reporter for New Scientist, based in Boston, Massachusetts. Follow her on Twitter @chelswhyte

TV

The Terror Prod. David Kajganich AMC

Chernobyl Dir. Johan Renck HBO/ Sky TV

Chelsea also recommends... TV

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This adaptation of Margaret Atwood’s dystopian novel continues, as resistance builds. At least there is hope.

Good Omens Terry Pratchett/ Neil Gaiman Prime Video

An angel and a demon team up to save the world.

32 | New Scientist | 22 June 2019

I AM not the kind of person who likes to be scared. I wouldn’t voluntarily go to a haunted house, and when I watch horror movies, I tend to scrunch up into a ball and peer through my fingers like a child. I have even been known to scream in cinemas. But, surprisingly, I haven’t been able to tear myself away from two completely terrifying recent TV shows. The first is the aptly named The Terror, a dramatisation of a mysterious 19th-century Arctic expedition led by naval officer John Franklin. On this ill-fated voyage, two British ships and the 129 men aboard them vanished while seeking the fabled North-West Passage, a stretch of water that runs through the icy seas off the northern coast of Canada, linking the Atlantic and Pacific oceans. It is full of executive producer Ridley Scott’s signature style: ominous music leading to jump scares. These make me shrink into the cushions on my couch. It is a show that plays on our fear of the dark and the unknown terrors that it holds.

The vastness of the Arctic makes for stunning aerial shots of the frigid sea that evoke a feeling of extreme isolation. Interior and exterior shots are taken from above, as if you are looking down on history, but the show doesn’t let the viewer off the hook – you also get up close and personal with

“These are stories that are driven by stubborn attitudes, by superiors who insist on keeping to a doomed path” the terror these men felt in the face of a wilderness they had the hubris to try to tame. HBO’s Chernobyl, a docudrama about the 1986 catastrophe at the nuclear power plant of that name, pulses with a different kind of horror. For the viewer, of course, it is very much a terror of the known. The depiction of the head-inthe-sand approach to the infamous reactor meltdown in what was then part of the USSR, and the effects of vast amounts of radiation spewing onto a nearby

town for days, is so frustrating that I was screaming at my television for entirely different reasons. This time it was the gentle cinematography and the quiet, simple moments that horrified, because I knew what the characters didn’t. In one scene, a few hours after the explosion at the plant, a young family joins their neighbours outside to watch the glow of the fire against the night sky as if attending a fireworks display. Flakes of ash begin to fall slowly around them, touching their cheeks and clothing and settling on their baby’s skin. The children of the neighbourhood look gleeful to be hopping around on a sand spit, playing in the falling “snow”. They couldn’t know that they were dancing to their doom. But I did, and was sick with horror. In both these dramatisations of real stories, things start badly and get worse. Both stories are driven by a stubborn push through insurmountable trouble – by superiors who insist on keeping to a doomed path. And for what? For the sailors, it is a dream of glory. For the politicians involved in Chernobyl, it is blind patriotism. The scariest part of both tales is that these actions and motives aren’t that difficult to empathise with. I’d like to think that if I found myself sailing into icy waters or facing the heat and radiation of a failed reactor, I would be smarter than these people were. I hope I would turn back, or call for help, or at the very least try to put the preservation of life before the tantalising taste of victory. But in reality, I don’t know if I would. Maybe that is the scariest part of all. ❚

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Features Cover story

Eight wonders of the human brain The more we learn about our command centre, the more mysteries arise. New Scientist goes in search of the biggest

What makes our brain special?

I

nside your head is an object capable of feats of computation, creativity and understanding unrivalled in the known universe – and all using the power of a 20-watt light bulb. We have made huge strides in understanding the human brain. In recent years, we have discovered that brain cells can regenerate and pinned down what happens when you start talking before you know what you want to say. Yet, the more we learn, the more we realise how much we still don’t know. In the following pages, we explore the biggest questions about the brain to reveal the mechanisms and mysteries of this phenomenal blob of grey goo.

34 | New Scientist | 22 June 2019

The human brain, we love to tell ourselves, is exceptional. Other animals might use tools or solve mazes, but can they invent computers or write sonnets? Yet even with our extraordinary mental prowess, it isn’t easy to explain what makes the human brain so special. At around 1.5 kilograms, our brains are about a third the weight of an elephant’s and a fifth that of a sperm whale. If body size is taken into account, however, our brains are unusually large: between seven and eight times what would be expected for a mammal our size. But this crude measure isn’t enough to explain our intelligence. The brain-tobody-size ratio of a capuchin monkey is higher than that of a gorilla, yet gorillas are considered smarter. Clearly size isn’t everything. A more important metric might be the number of neurons – the brain’s processing units. Humans have about 86 billion, according to Suzana Herculano-Houzel of Vanderbilt University in Tennessee, who has pioneered methods to count them. In fact, primate brains have more neurons than other mammal brains of comparable size. Humans, having the largest brain of any primate, also have the most neurons of any primate, and probably any animal. This was possibly enabled by the invention of cooking,

which releases more calories from food to fuel this energetically expensive organ. It isn’t only the number of neurons that matters, but also where they are. Our remarkable abilities probably stem from having more neurons in our cerebral cortex – the brain’s wrinkly outermost layer – than other animals, says Herculano-Houzel. This structure allows us to develop more complex behaviours rather than simply responding to stimuli. “If you have a cortex, you are no longer a slave to what happens around you. You have the flexibility to choose to do things otherwise,” says Herculano-Houzel. What’s more, her team recently discovered that across warm-blooded animals, the number of neurons in the cortex correlates with longevity. Herculano-Houzel thinks this is also a factor in our cognitive superiority: humans take years to reach maturity. “We take a really long time to put that brain together,” she says. “All the while, you are assimilating information from the world.” Neurons aren’t the whole story: cells called astrocytes also play an important role in intelligence (see “What makes a brain”, page 40). But the sheer computing power afforded by our 16 billion cortical neurons is likely to be the critical factor behind our cognitive dominance. Sam Wong >

LIAM MADDEN

22 June 2019 | New Scientist | 35

What is consciousness?

36 | New Scientist | 22 June 2019

as experiences. But the brain presents to our consciousness only what matters to us, and does so in a way we can understand. For example, it is why we see things as being a particular colour. The real world isn’t like that, but our visual systems effectively colour-code the world for us, to simplify it.

Illusions of the mind Dennett argues that much as colour is an illusion created by the brain, so too is consciousness. “Consciousness is a user illusion designed by evolution to make life easier for the brain that must guide a body through a perilous life,” he says. Smartphone designers call the screen of a phone a user illusion. The screen is the interface to the computer underneath, but the icons on it – such as the envelope that depicts a message – are symbolic, and don’t bear any relation to the actual hardware and software of the phone’s messaging system. If our brain is a smartphone, consciousness is the screen, our interface to the brain. However, as Churchland

says, the metaphor isn’t exact. When we feel dizzy or pinpoint where a sound is coming from, for example, it is the result of physical processes in the brain. Perhaps consciousness is more like a smartphone screen that presents different apps according to the amount of battery left or how much it has been shaken. Consciousness, in other words, is a partial illusion, a picture knitted together by the brain as a result of all the inputs it is receiving and the completeness of the brain broadcast. Rowan Hooper

“If our brain is a smartphone, consciousness is the screen” Gamma brainwaves

Neural ripples Gamma waves are one of five types of brainwave, each oscillating at different frequencies and associated with different tasks. The others are alpha, beta, delta and theta waves

PLAINPICTURE/SILVERI

Think of the conscious mind as a furnace. If you are deeply asleep, the flame of consciousness has died down to a low but persistent level. In REM sleep, when you dream, the flame is jumping and burning brightly but erratically. In a coma, it is a glowing ember. Consciousness, in other words, exists in a range of states. One explanation for this is that full consciousness erupts when many parts of the brain broadcast information to a network of neurons known as the global workspace. When this broadcast doesn’t take place, sensations remain subconscious. When the broadcast is incomplete, you get different levels of consciousness, such as when you are dreaming or have had a blow to the head. By studying these states, we should one day be able to pinpoint the brain mechanisms that give rise to consciousness. So why then, has explaining consciousness – how a kilogram or so of nerve cells conjures up the swirl of thoughts and emotions that make up our mental experience – been dubbed “the hard problem”? One reason is that philosophers have focused on explaining how we become aware of experiences. Their term “qualia” describes the properties of experiences we have, such as the redness of a strawberry or the perception of the taste of wine. Trying to find explanations for qualia has caused no end of confusion among neuroscientists. One solution to the problem is to ignore it. “‘Qualia’ is a term of art, introduced by philosophers who want to make the questions about the nature of consciousness answerable only by spooky, non-biological accounts,” says Patricia Churchland at the University of California, San Diego. After all, we don’t normally talk about our qualia, we talk about things such as being tired, needing to eat or even being in love – feelings that have a straightforward, non-spooky biological origin. Most people aren’t aware of their qualia until they are prompted by philosophers, says Daniel Dennett of Tufts University, Massachusetts. Dennett not only thinks that there is no hard problem, he believes consciousness itself is a kind of illusion. “It takes some substantial coaxing and cajoling to get people to ‘notice’ their qualia,” he says, “and when they think they do notice them, they are falling for another illusion.” The illusion, according to Dennett, is this: each of us believes that we have privileged access to some remarkable properties of our own mental states, with which we are intimately acquainted and which we perceive

When we consciously pay attention to something, what is going on in the brain?

Are smarter people’s brains different? The short answer is yes. People vary in their intelligence, so how else could we account for this if not for differences in the structure or function of the brain? Exactly what those differences are, however, is a matter of intense investigation. The first thing to note is that people with larger brains really do tend to have higher IQs, but there is more to this than size (see “What makes our brain special?”, page 34). To find out more, we need to zoom into the white and grey matter that makes up our brain. The latter is comprised of the main bodies of neurons, whereas white matter is made of the fibres down which they send signals. Rogier Kievit at the MRC Cognition and Brain Sciences Unit in Cambridge, UK, and his colleagues have found that the volume of grey matter in the frontal lobe (see diagram, right) is connected to fluid intelligence, which is the ability to solve novel problems. They also found this was linked to the amount of white matter connections between the two halves of the prefrontal part of the brain. It isn’t just the amount of tissue that counts. One of the most striking features of the mammalian brain is the way it has deep folds of grey matter on its surface, giving it a walnut-like appearance. These increase its surface area, bringing cells closer together and allowing them to communicate faster. And sure enough, the extent of the folding is correlated with speed of thought and working memory: smarter people have more-folded brains. But this still doesn’t tell us where in the brain intelligence resides. To find this out, we can turn to one of the most popular ideas about its location, something called parieto-frontal integration theory. This proposes that the biological basis of intelligence is a network connecting different brain hotspots. Clues about these hotspots can be found in brain-imaging studies. By examining how parts of the brain became activated during cognitive tasks, Ulrike Basten at Goethe University Frankfurt in Germany and her colleagues identified a network connecting 20 different areas in the frontal and parietal regions that were associated with intelligence. People with more grey matter or higher neural activity in these regions were smarter. It feels like we are getting somewhere, but that result doesn’t just mean that

Know your brain The human brain operates using specialised processing units

Frontal lobe Problem-solving, complex thinking, decisions

TOP BRAIN Creates and monitors plans

Prefrontal cortex Planning complex behaviour

BOTTOM BRAIN Classifies and interprets information

Motor cortex Planning and executing movement Parietal lobe Integration of sensory information, perception Occipital lobe Visual processing Visual cortex

Temporal lobe Language, hearing, processing sensory information into memories

smarter people have physically different brains: they seem to have ones that work more efficiently too. A brain might have the right chassis for high performance, says Emiliano Santarnecchi of Harvard Medical School, “but it’s not that relevant without an on-board computer regulating how power is delivered and when to allocate resources at any given moment”. Santarnecchi’s work suggests that intelligence can be boosted by magnetic stimulation to increase the brain’s processing efficiency. He also emphasises the importance of plasticity, or the ability to change. Perhaps some people’s brains are inherently more plastic, more capable of learning. This is to say nothing of genetics. Although we know that hundreds of genes contribute to intelligence, it is going to take a long time to discover the nuances of their impact. But then it was never going to be a simple matter to find the location of intelligence, the richest human trait, in the brain, the most complex known object in the universe. RH

850,000 kilometres of nerve fibres SOURCE: AI IMPACTS

Alpha brainwaves

Auditory cortex Hippocampus Memory

What happens when we think? Think about thinking, and it doesn’t take long for your mind to go down a rabbit hole. Thoughts come naturally to us, but pinning down exactly what they are is more complicated. Once they were viewed as immaterial entities, separate from the biological matter of the brain. Now we know that our every thought – whether about a simple object or an abstract idea – is the result of electrical signals pulsing through the brain’s network of 86 billion neurons. “For me, a thought is simply the transformation of inputs to outputs by the brain,” says Ethan Solomon at the University of Pennsylvania. But if you ask 100 neuroscientists for a definition, you will get 100 different answers, says Avgusta Shestyuk at the University of California, Berkeley. “‘Thinking’ is an umbrella term that covers multiple different cognitive processes,” she says. Some thoughts take the form of pictures, others seem to be comprised of words, and many take place at the unconscious level, without us even noticing. The latest neurological studies let us tune into the electrical signals that underlie thinking. They show that even a basic > 22 June 2019 | New Scientist | 37

Are you really left or right-brained?

DORIS RUDD DESIGNS/GETTY

Are you thinking what I’m thinking?

Theta brainwaves

“Mind-reading devices are no longer the stuff of science fiction”

thought involves a surprising amount of activity, with different brain areas firing up and sending information to others, and certain “hub” regions directing the traffic. Last year, for example, Shestyuk and her colleagues recorded the journey of individual thoughts in the brain by measuring the electrical signals involved when people were asked to recall and say a word. The first areas to show activity were the visual and auditory cortices, which receive signals from the eyes and ears. Next, the brain’s command centre – the prefrontal cortex – kicked in. The harder the memory task, the more of the prefrontal cortex that became activated, 38 | New Scientist | 22 June 2019

and the longer it took to respond, reflecting the time taken for the region to recruit other brain areas such as networks where memories are stored. Finally, the motor cortex revved up to generate a spoken response. Surprisingly, this happened before the prefrontal cortex had decided on a response. “That’s why we sometimes start speaking before we know what we want to say,” says Shestyuk. So, the prefrontal cortex helps orchestrate thought processes, but the signals involved also need to be coordinated. That is the job of brainwaves: ripples of neural activity oscillating at different frequencies across the brain. Solomon’s research reveals that during a memory test, low-frequency theta waves in the various brain regions involved become coordinated, and this synchronisation probably allows information to be communicated between the regions. Our new-found ability to eavesdrop on individual thoughts means that mindreading devices are no longer just the stuff of fiction. Earlier this year, electrodes on the brain were used to translate brainwaves into words spoken by a computer. Techniques like these could help people with locked-in syndrome – who are conscious but unable to move – to communicate. All thanks to the power of thought. Alison George

Chances are you have thought of yourself as left or right-brained: rational and logical, or creative and free-spirited. Appealing as this concept is, it is also a complete myth. It is easy to see how the idea was born. In the 1960s, we discovered that certain functions occur solely on one side of the brain. Most people process language in the left hemisphere, whereas our emotions are dealt with in the right. It was soon said that our left hemisphere held a monopoly over the virtues of logic, reason and language. The right side of the brain was responsible for driving our emotions, musicality and impulsiveness. From this came the popular maxim that whichever side of your brain dominated, determined your personality. The truth is more nuanced. For instance, although your left hemisphere produces complex speech, the right allows you to understand the emotional and metaphorical content of those words – it gives you some linguistic finesse. Creative thought, on the other hand, activates a widespread network of cells that favour neither hemisphere. Moreover, there is no evidence that one side of the brain dominates. Jeffrey Anderson at the University of Utah has scanned the brains of more than 1000 people while they performed various tasks and showed that none revealed a dominance for using one side of their brain over the other.

Top to bottom Other ideas abound. The “theory of cognitive modes”, developed by Stephen Kosslyn at Harvard University, holds that our cognitive style is determined by whether we are top or bottom-brained (see diagram, page 37). The top regions of our brain are involved in formulating and carrying out plans, and revising them when they go wrong. Lower regions are largely concerned with processing inputs from the senses, classifying objects and events, and giving them meaning. Everyone uses their whole brain all of the time, says Kosslyn, but each of us to some extent relies more on top or bottom systems, and this affects our behaviour. A top-brain dominated person, for instance, will be more of a creative go-getter, but sometimes ineffective because they don’t update plans based on current

Is your brain ever off? circumstances. Bottom-brained types think through the details of a plan but are less likely to initiate complex schemes. Anderson, however, posits that our personalities probably arise from the way various brain systems are connected and how rich those links are. For instance, people who are open to new experiences are more likely to get goosebumps when they see a beautiful sunset. Brain scans show that they have more connections between areas that process sensory information and regions responsible for our inner voice. We can feed this information into deep-learning machines that can make accurate predictions about personality traits based on a person’s brain scan, says Anderson. “It’s not about anyone using the left or right side of the brain more,” he says, “it’s about subtle differences in connections across the whole brain.” Helen Thomson

When you rest, it sometimes feels as if your brain switches off too. It doesn’t. If you are alive, your neurons are firing. “There is a lot of processing going on even when you’re not seemingly doing anything at all,” says Deniz Vatansever, a cognitive neuroscientist at Fudan University in China. It could hardly be any other way. Momentto-moment readiness was a matter of life and death for our ancestors. These days, most of us don’t have to worry about leopards leaping from the undergrowth. But we still need to be alert to dangers and

Estimated memory capacity of the human brain

opportunities, and that requires a brain that is working constantly. Back in the 1990s, neuroscientists noticed that people lying quietly in brain scanners with their eyes closed showed surprising levels of brain activity. The researchers soon mapped the brain regions that are most active during rest, and this became known as the default mode network. This shows little activity when we are engaged in tasks requiring attention, but fires up when we “switch off”, allowing our minds to wander. Some evidence suggests that the default mode network is involved in mulling over past experiences and speculating about the future. In that sense, it is vital because daydreaming is considered to be one of the abilities that sets us apart from other animals. But the default mode network does more than that. In 2017, Vatansever and his colleagues demonstrated that it underlies our ability to do certain things without paying attention, such as tying our shoelaces or driving along a familiar route – our autopilot mode.

[equivalent to that of the World Wide Web]

Shutting down

~1 petabyte SOURCE: ELIFE, DOI.ORG/GDZ74X

The brain is a hive of activity during sleep, too. Once consciousness is lost, it gets to work on all manner of chores: clearing out toxic molecules, regulating hormone levels and conjuring dreams, which are thought to provide a safe environment to simulate new behaviours that could help during waking life. The sleeping brain also files away experiences for later recall. Even when someone is in a vegetative state, unconscious and apparently unresponsive for a prolonged period, their brain continues to work at some level. When some people in this state are asked to imagine themselves playing tennis, for instance, blood flow increases in brain regions associated with motor skills, suggesting that the neurons there are firing. In one case, a patient seemingly activated those regions on command in response to yes-or-no questions. Only when you die do your neurons completely shut down. Except even then, there is a final burst of activity, as Jed Hartings at the University of Cincinnati in Ohio and his colleagues recently showed for the first time in humans. When the heart is no longer pumping blood to the brain, starving it of oxygen, neurons draw on energy reserves to continue firing for up to 3 minutes before they produce one last burst of electrochemical energy. Only then is the brain switched off for good. Daniel Cossins > 22 June 2019 | New Scientist | 39

We often say we make decisions on the basis of gut feelings, and this may be truer than we realise. Nausea, for instance, makes us judge certain moral violations more harshly. This is just one of many ways in which our gut influences what goes on in our head. It is easy to forget that the gut is a sense organ, detecting incoming nutrients, toxins and pathogens, and relaying that information to our brains. It contains some 500 million neurons that coordinate the process of digestion. The gut is also home to about 2 kilograms of bacteria: our microbiome, which influences every organ in the body, including the brain. A wealth of studies in mice show that changing the bacteria in the gut can change behaviour – in some cases, turning the animals into antisocial loners. The microbiome may be particularly important in childhood, while the brain is still developing. Mice that lack microbes called Bifidobacteria in their gut during infancy seem worse at learning new information, for example. Evidence from humans is accumulating, too. One imaging study found that consuming a fermented milk drink containing various strains of live bacteria had a profound effect on people’s resting brain activity and their responses to seeing faces showing emotion. This year, a study of 1054 people in Belgium found that certain types of gut bacteria are less prevalent in people with depression. There are also tantalising hints that certain neurological conditions, such as autism, and diseases, like Alzheimer’s, may originate in the gut. In Parkinson’s, synuclein fibres,

a hallmark of the disease, seem to appear first in the gut before spreading to the brain. We don’t know what triggers it, but it could be an unknown microbe or toxin. In epilepsy, changes to the microbiome may explain why the high-fat “keto” diet prevents seizures in some people. Research on the gut-brain connection is in its infancy, but it has sparked the idea of medicines that target the microbiome to improve our mental health – dubbed psychobiotics. John Cryan at University College Cork, Ireland, believes it is an exciting prospect, but a lot more work is needed to pinpoint which bacteria are beneficial for which conditions and how to deliver them to the gut. How bacteria actually influence the brain is also something of a mystery, but the picture is becoming clearer. The tens of trillions of bacteria in our gut are a hive of metabolic activity, producing a wealth of chemicals that we can absorb. Working out which ones get to the brain and exert effects there is a big focus of current research. Some bacteria even feed on GABA, a brain chemical implicated in depression. It might seem odd that our brains are influenced by what is in our guts, but it isn’t so surprising when you consider that these microbes have always been with us, says Cryan. “I see them as friends with social benefits because they really affect the social brain in early life and development,” he says. “This relationship is very important and I think it’s been evolutionarily wired.” Sam Wong

ROBERT CLARK/NATIONAL GEOGRAPHIC IMAGE COLLECTION/GETTY

Does the gut influence the mind?

“The human brain starts to shrink around the age of 40”

WHAT MAKES A BRAIN A few years ago, scientists took human brain cells and injected them into mice. A year later, the cells had multiplied and the mice had got smarter, learning more effectively than mice with regular brains. Perhaps that isn’t so surprising – until you hear that these brains cells weren’t neurons. As building blocks of the brain go, neurons hog the attention. There are some 86 billion of these stringy cells carrying electrical impulses around the brain, helping us to control our bodies and think thoughts. But there are plenty of cells in the brain that aren’t 40 | New Scientist | 22 June 2019

electrically active. These are known as glial cells, and they are at least as numerous as neurons. A type of glia called an astrocyte was injected into those mouse brains, suggesting – not for the first time – that they could be important in learning. Glia used to be considered mere gap fillers. No longer. “There is a lot of evidence to say they are more than just glue,” says Anne Cooke, chief executive of the British Neuroscience Association. “They are the unsung heroes of the brain.” They come in different types. Small ones called microglia, for instance,

roam the brain gobbling up foreign material to protect the neurons. Astrocytes take care of the neurons’ environment too, controlling levels of chemical messengers known as neurotransmitters and helping to repair damage. Evidence is mounting that these cells also have a role in the development of human intelligence. We know that babies start off with many connections between their neurons and that these are gradually pruned down to create smaller numbers of stronger signalling pathways. Astrocytes, it seems, are involved in this pruning.

“While neurons are still very important, it seems that glial cells are involved in setting the gain on the system,” says Ed Lein at the Allen Institute for Brain Science in Seattle. It isn’t all about cells. Holes play a part too. Deep inside your head there are slim chambers called ventricles that produce the fluid that bathes the cells of your brain. We make as much as 500 millilitres of this cerebrospinal fluid daily, which keeps everything in working order by providing cushioning and nutrients, and washing waste away. There is no doubt plenty more to be discovered. Just last year,

What makes some brains more resistant to decline? It is a harsh fact of life: as you get older, your cognitive abilities start to wane. But why is it that some people reach a ripe old age with little more than the odd “senior moment”, while others have far greater mental decline? The brain starts shrinking around the age of 40, with cells deteriorating most quickly in the frontal lobe, the striatum and the hippocampus – areas involved in our most complex thoughts, movement and memory. How resistant you are to the effects of this decline is likely to be associated with your cognitive reserve. This is a kind of mental buffer that allows your brain to sustain more damage before you notice changes in your cognition. Cognitive reserve isn’t just down to someone having more neurons than another person, but also to how well their neurons engage with each other across different networks in the brain. This allows the brain to compensate when age-related decline occurs or disease takes hold, and helps reroute information so that the organ can continue to work optimally. It is a bit like boosting the processing power in a computer: more things can go

Beta brainwaves

researchers identified a new type of brain cell, dubbed a rosehip neuron due to its resemblance to the shape of a rosebush fruit. It may only exist in humans. Other secrets may well be revealed by Lein’s ongoing efforts to create a map of all the brain’s cell types, painstaking detective work that looks at the genes single cells express. He has recently studied the neocortex – the outer part of the human brain that deals with higher processes and makes up 80 per cent of its mass – and found 75 different types of cells there alone. Joshua Howgego

K.H FUNG/SCIENCE PHOTO LIBRARY

Mind reading: new technology gives us an unprecedented view of the brain in action

Of all primates’ brains, those of humans have the foldiest outer layer

wrong before you start to notice it slowing down. Our environment can also influence cognitive reserve. A high level of education offers one of the biggest boosts, whereas obesity and insulin resistance seem to reduce it. Several genes also help us resist cognitive decline. Tiny genetic variations are associated with our susceptibility to Alzheimer’s as well as with how the brain utilises energy reserves and reacts to injury and pathogens.

Exercise the mind Brain shrinkage over time sounds bleak, but there is some good news. Although most of our brain cells are created soon after birth, we can make certain types of neuron even into our 90s. This ability might go some way in explaining why some people’s brains fare better against the ravages of old age. There are a few other ways to boost cognitive reserve. Continuing to educate yourself throughout your life appears to provide one of the biggest benefits, but playing a musical instrument, socialising, getting the right amount of sleep and speaking more than one language also help. Don’t put your feet up for too long though: the adage “healthy body, healthy mind” turns out to be true. “If you’re looking to maintain brain health, you need to exercise,” says Steve Harridge, director of the Centre for Human and Applied Physiological Sciences at King’s College London. Regular workouts bring about significant improvements in memory, attention, processing speed and executive functions, such as planning and multitasking. And don’t leave it too late. Richard Henson at the University of Cambridge and his colleagues have discovered that the things we do in midlife – outside of work and education – make a unique contribution to brain health in older age. The activities retirees do in their old age, however, had less impact. “Midlife seems to be a good time to intervene, to nudge people into taking part in more activities – physical, intellectual and social – that might bode well for them 20 or 30 years later,” says Henson. ❚ Helen Thomson 22 June 2019 | New Scientist | 41

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Features

Worst of all possible worlds Mercury and Venus are two of Earth’s closest cousins, says Leah Crane. So how did they turn out so hellish?

42 | New Scientist | 22 June 2019

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LOSE to the sun lie a pair of sizzling coals. You could be forgiven for thinking these strange worlds were two circles of hell: Mercury, a black and blasted plain, and Venus, a sweltering world beset by rain of pure acid. But for all the terror of their outward appearance, their insides are remarkably familiar. Along with Earth and Mars, they form the solar system’s only rocky planets, a stark contrast to the bloated gas giants that make up its outermost worlds. In the language of those hunting for extraterrestrial life, such planets count as potentially habitable. In fact, if  we found a Mercury or a Venus in a solar system far from our own, we might even call them Earth-like. So what caused these seemingly Earth-like planets to become so resolutely, well, not? Was it some accident of composition, or millions of years spent in an inhospitable environment? Getting to the bottom of these questions, and understanding the diversity of rocky planets, is of paramount importance for astronomy. Without clear answers, we aren’t only ignorant

of our own solar system’s history, but blinkered in our search for life elsewhere. Part of the problem is that the innermost planets are incredibly hard to visit. Only two spacecraft have ever made it to Mercury and of the numerous Venus landers, none survived longer than 90 minutes. Painting a more detailed picture will involve a new generation of probes, such as the European Space Agency and Japan Aerospace Exploration Agency’s BepiColombo, currently on its way to Mercury. While the chances of finding any signs of life are close to zero, the data it sends back will help us look for it elsewhere. To find out anything about Mercury, though, we first have to get there. The biggest problem when it comes to planning a trip to Mercury is the sun. When your next-door neighbour is a star 6 million times heavier than you with a gravitational field 80 times stronger, visitors have a tendency to get redirected. If a spacecraft flies by Mercury too quickly, it will be trapped by the sun’s powerful gravity and dragged to its doom. But even heading

Mercury (left) and Venus (right) remain largely mysterious

straight for the planet doesn’t guarantee you will arrive. “The second you point your rocket toward Mercury, you are going far too fast to get caught in Mercury’s gravity,” says Paul Byrne at North Carolina State University. The sun has so much gravity that a direct mission to Mercury will always miss. We didn’t know how to get into orbit around Mercury until the mid-1980s, when Chen-Wan Yen at NASA’s Jet Propulsion Laboratory in California figured it out. A spacecraft has to take the scenic route, with loops around Earth and Venus and multiple swoops past Mercury to slow it down before it can enter orbit. The first probe to visit was Mariner 10, which flew past, rather than orbiting, just three times in 1974 and 1975. The second was Messenger, which orbited for four years from 2011. “We had Mariner 10 go by, and it was craters and all a little bit boring,” says David Rothery at the Open University, UK. “We would still wonder > 22 June 2019 | New Scientist | 43

Volatile nature In theory, most volatile elements on Mercury’s surface should have already boiled away due to its proximity to the sun. But they are still there. “Before we got there, we had this idea that it should be depleted in volatile elements,” says Kathleen Vander Kaaden at the Lunar and Planetary Institute in Texas. “And then we get there and we realise that there are lots of these volatiles on the surface.” On a planet with no liquid water and little weather, these volatiles play a key role in shaping Mercury’s surface features. In addition to powering its volcanoes, they are also responsible for Mercury’s most un-Earthlike attribute. Instead of an atmosphere, the 44 | New Scientist | 22 June 2019

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if Mercury was boring if we hadn’t had Messenger there to prove it wasn’t.” One thing Messenger experienced directly was just how hot the planet gets. The orbiter had to periodically back away from Mercury just to keep its instruments cool – on the day side, the surface reaches temperatures of up to 430°C. And because there is barely any atmosphere to hold heat in and spread it around the planet, the temperature drops precipitously on the night side when the sun sets – down to about -175°C. Day and night are drawn out affairs, too: with an average of 176 Earth days elapsing between sunrises, one day is longer than the planet’s year. These temperature extremes mean life as we know it is almost impossible on Mercury. There are a few sunless craters near the poles that may have a small amount of water ice, but they are probably too cold for liquid water, with little or no oxygen. “Pretty much every place gets very hot and very cold,” says Byrne. “It’s not great if you’re a bug, let alone anything more complicated.” The low surface pressure and lack of air make it even less hospitable. More problems come from within. The planet is intensely volcanic, says Lillian Ostrach at the US Geological Survey’s Astrogeology Science Center in Arizona. “The whole northern plains area, which makes up more than 10 per cent of the surface, is solidified lava.” Mercury has signs of what is known as explosive volcanism, a more dramatic type of eruption. Elements that boil at relatively low temperatures, known as volatiles, form gas bubbles in lava, which pop at the surface to spew hot liquid rock in all directions. Most of these eruptions seem to have happened about 3.8 billion years ago, when much of Mercury’s interior was still molten from the heat of formation.

tiny planet has an exosphere, a thin and tenuous layer of particles floating above the surface. “It’s not so much an atmosphere as a slow evaporation of the planet,” says Valeria Mangano at the National Institute of Astrophysics in Rome, Italy. The exosphere is mostly hydrogen and oxygen, with some helium, sodium and potassium as well. It probably forms when charged particles from the sun sneak through the planet’s magnetic field and hit the surface, sending tiny particles of dust and gas flying. “It is continuously created and continuously fading away into space,” says Mangano. You read that right, Mercury is slowly shrinking. The process isn’t only powered by evaporation, either. As its molten core began to cool, the planet started to solidify, causing its surface to contract. Cliffs on the surface that can be up to about 1000 kilometres long and 3 kilometres high show that its diameter has shrunk by several kilometres since its crust formed, crumpling the landscape. As Mercury’s

“Mercury’s surface is continuously fading away into space”

Mariner 10 gave us our first close-up glimpse of Mercury in 1973

surface is all one shell rather than several tectonic plates, these cliffs probably couldn’t have formed any other way. But despite millions of years of cooling, some of the core is still liquid. Part of the reason it has taken so long to freeze may be simply that the core is enormous. It takes up 85 per cent of Mercury’s radius – far more than any other planet we know of. Dig just a few hundred kilometres through the crust and you will hit molten iron-rich core. On Earth, you would have to dig almost 3000 kilometres to reach the outer edge of the core. This thin veneer of rock over a huge core, combined with the unexpected volatiles, has led some researchers to conclude that Mercury may have formed further from the sun and then smashed into another, larger protoplanet as it migrated inward, stripping off its rocky outer layer. “It could come in and hit the young Earth or the young Venus and lose its rock but not its volatiles in the process,” says Rothery. Without this hit-and-run, Mercury might be a much bigger planet, and one more structurally similar to Earth. Planetary scientists are still scratching their heads over the mysteries Messenger revealed. Which is where BepiColombo comes in. The hope is that it will answer some of those questions. BepiColombo consists of two orbiters that will separate when they reach

Mercury and provide the most comprehensive global view we have ever had of the strange little world. It launched in 2018, but because of the convoluted path necessary to skim safely into orbit, it won’t arrive until the end of 2025. Meanwhile, Venus has been unloved of late. “Venus is sort of the middle child,” says Tracy Gregg of the University at Buffalo in New York, less loved than the favoured siblings of Mars and the gas giants. Of the 27 successful visits since 1962, only five occurred after 1990. That means our knowledge is even less up-to-date than it is for Mercury. It isn’t that Venus is particularly hard to get to – it is just hard to learn about once you get there. “The Soviet landers lasted between an hour and an hour and a half on the surface before, essentially, they cooked,” says Gregg. Surface temperatures are around 470°C, with crushing pressure from the heavy atmosphere 90 times that at sea level on Earth. Venus’s inhospitable conditions have very different origins to Mercury’s. “Usually people think that Venus is so warm because it’s nearer to the sun than Earth, but it’s not true,” says Pedro Machado at the Institute of Astrophysics and Space Sciences in Portugal. “Its clouds reflect around 70 per cent of incoming radiation from the sun.” Instead, Venus is hot because of a runaway greenhouse effect – its thick carbon dioxide atmosphere traps heat near the surface. That thick haze, which inexplicably rotates 60 times faster than the solid planet, means that the heat gets distributed all around the world instead of radiating away into the chill of space at night. Unlike Mercury, there is no cold side. The atmosphere also hides the surface from orbiters, so we have very limited data on what lies below the Venusian clouds. “We don’t know what Venus is made of,” says Byrne. “We don’t know if it’s still tectonically active, we don’t know what the cratering rate is, we don’t know why its atmosphere is moving so fast.” Venus is a place of mysteries. From radar data, we can see that it has what appear to be volcanic landforms: channels carved by lava, plains of volcanic rock and in excess of 1600 major volcanoes – more than anywhere else in the solar system, even though there is no evidence that they are active now. It is also home to the longest channel in the solar system, which once carried lava nearly 7000 kilometres. But nobody knows where the lava came from or where it went after creating the channel. “We don’t see a big pile of lava at the end of these channels. We don’t see a volcanic mountain or a volcanic crater at the beginning of these channels,” says Gregg.

“These channels on Venus have no source, no sink, and yet there they are.” There are also strange bright areas of terrain called tesserae, which tend to be full of long ridges and troughs that form when the crust shifts due to tectonic activity. There have been hints from landers that these areas may be rich in silica, like continental crust on Earth. “If we were to determine that the tesserae were continental crust, it would be a big finding, because it would mean there was much more complicated geology and chemistry than is happening now,” says Byrne. Crucially, this would also be one of many areas of similarity to Earth. “Venus and Earth should be twins,” says Gregg. “They are made up of the same stuff, they are about the same distance from the sun, they are about the same size. And yet…”

Planetary popularity contest Exploration of our solar system used to be mainly about Venus, but in recent years, Mars has been prioritised. Of the four rocky planets, Mercury remains relatively unloved NASA

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“Venus and Earth should be twins. They are made up of the same stuff. And yet...” If Venus and Earth formed close to where they are now, they should have about the same amount of water, whether they formed with it or got it from meteorites later on. There is no obvious reason for Venus to be so different, aside from maybe that a lack of plate tectonics made it difficult to sequester carbon dioxide in rocks. Early in its history, Venus may even have been pleasant for life, with surface water and a less dense atmosphere. Not now. “Being on the surface is like diving in the ocean at a depth of around 1 kilometre, and it’s also like an incinerator,” says Machado. “There are better places to go for a holiday.” Perhaps the implausibility of life on Venus and Mercury is why it has been hard to build interest in visiting them. “We are probably not going to find life there,” says Machado. “And we can’t go to the surface with an astronaut one day and put a flag in the soil.” Nevertheless, they may be important for us. “The goal is not just to understand Mercury or Venus,” says Byrne. “It’s to understand our own world. It’s to understand other worlds around other stars.” And to fathom those other worlds, it is important to figure out why the four rocky planets in our own solar system are so different from one another – and why only one seems to be right for life. “To understand our own planet – and even exoplanets – we need to understand the three others as well,” says Rothery. Yet for only one of them, Mars, do we even know what the surface is predominantly made of or where all the water went. Comprehending the differences that seem so monumental here could help us parse the tiny dissimilarities we see between worlds circling other, distant stars. “A seemingly Earthlike exoplanet could be a paradise planet like Earth or a hell planet like Venus,” says Machado. To tell which is which, we are going to have to return to the two sizzling coals nearest the sun. ❚ Leah Crane is a reporter at New Scientist. Follow her on Twitter @DownHereOnEarth

missions that visited multiple planets 22 June 2019 | New Scientist | 45

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