Humans

Many of us aim for “recommended dailies” such as 10,000 steps, 2000 calories or 2 minutes of tooth brushing. But where do these figures come from and are they supported by evidence?

Humans

8 September 2021

By Amelia Tait

Shutterstock
FOR as long as I can remember, certain numbers have inhabited my head: Five fruit and veg a day, 8 hours of sleep, 2000 calories, 2 minutes of tooth brushing, eight glasses of water, 10,000 steps.
For want of a better term, these are the “recommended dailies”: numbers that are etched onto our brains as the ones we should live by. But for all their influence, it is unclear whether sticking dutifully to them actually makes a difference to our health. So I decided to get to the bottom of things, attempting to live my own life by the numbers (see “Living the dream”, page 41) while also digging into some critical questions about them: who came up with these figures in the first place? How solid is the scientific basis for these magic numbers? More to the point, is sticking to them really worth the effort?
Brush your teeth for 2 minutes, twice a day
Keeping your teeth clean isn’t just a way to avoid the dentist’s drill (and bill) – the bacteria that cause gum disease have also been linked to an increased risk of developing Alzheimer’s. People with gum disease also have a two to three times greater risk of having a stroke or heart attack, and while a causal link hasn’t been shown, there are suggestions that gum disease increases markers of inflammation in the blood.
The benefit of brushing is that as it removes thin films of plaque bacteria from the teeth, it breaks up bacterial communities, disrupting the opportunity for social evolution. This essentially stops them evolving into super bacteria that are experts at … More

By Tiffany O’Callaghan

A herd of wild Asian elephants strolls through a village in ChinaVCG via Getty Images
Book
Fuzz: When nature breaks the law Mary Roach
WW NortonAdvertisement

MARY ROACH has a knack for choosing subjects for her books that won’t have necessarily crossed your mind and convincing you that you must now know everything about them. She has covered the logistics of strapping cadavers into cars to use as human crash test dummies (Stiff), how studying what orgasms look like in the brain requires people to get busy in an MRI scanner (Bonk), pondered the literal ins and outs of what competitive eating does to your digestive tract (Gulp) and contemplated how astronauts poop in space (Packing for Mars, a rare deviation from her single word titles).
In her new book, Fuzz: When nature breaks the law, her subject is the unfortunately now familiar issue of human-wildlife conflict. But she hasn’t decided to switch gears and approach her subjects from a place of earnest lamentation, in this case about the perils of our encroachment on wild habitats. Instead, with her characteristic dry wit, she brings an intense fascination to the seldom discussed details and the at times absurd miscellany in the unexplored corners of unappreciated research.
The opening chapter finds her at a wildlife forensics conference, where she learns about what happens after a human is mauled by a wild animal. The focus of the Wildlife-Human Attack Response Training conference is mainly bears in the Pacific Northwest. We learn that very often the culprit is identified and killed, but occasionally the backwoods whodunnit turns up a surprise: a “gnawed on corpse” is no smoking gun. An opportunistic omnivore does occasionally stumble on a human already dead from other causes.
Each chapter explores a new type of conflict, from elephants that stomp their way across crops (and people) to albatrosses that get sucked into jet engines, leopards that attack people to deer that collide with aircraft (yes, you read that right).
Along the way you pick up plenty of helpful tips. The best makes of car if you plan to survive crashing into a moose? Saab or Volvo. The most cost-efficient way to keep birds from eating your harvest on a small farm? Humans regularly chasing them off.
As to whether you should stay still or fight back in a hostile bear encounter, it largely depends on what kind of bear it is, “black fight back, brown lie down” as the ditty goes. The trouble is, as Roach points out, some brown bears’ fur can be black, and some black bears look pretty brown.
“It’s impossible not to smirk, chortle and sometimes outright belly laugh as you read the many wry asides”
“A more reliable way to distinguish the two is by the length and curvature of their claws,” she says, before conceding that, “by the time you’re in a position to make that call, the knowledge will be of limited practical use.”
It is impossible not to smirk, chortle and sometimes outright belly laugh as you read her many wry asides and funny but fascinating footnotes.
A particular favourite for me has to do with the surprisingly persistent myth that birds will explode if they eat the rice tossed at weddings: “Some churches ban the practice anyway, not because it’s perilous for birds but because it’s perilous for guests, who could slip on the hard, round grains and fall and then fly off to a personal injury lawyer.”
She provides an ample supply of factoids to regale your friends with. Did you know that it is our “looming sensitivity” that helps us and other animals anticipate how fast something is coming at us, so we can get out of the way? (Or not, see the earlier mention of deer and aircraft.)
But the real trick Roach pulls off is to keep you laughing while at the same time making sure the earnest points come across. Among the many that stuck with me is that before the 1980s, wildlife and wilderness were conserved in the US to provide good hunting and fishing. It is only recently that “conservation” has been about protecting these areas and creatures for their own sake.

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By Michael Marshall

Human brains have been shaped by DNA that evolves quicklycomotion_design/Getty Images
Many of the fastest-evolving sections of the human genome are involved in brain development. These rapidly changing segments of DNA may have played key roles in the evolution of the human brain and in our cognitive abilities.
Chris Walsh at Boston Children’s Hospital in Massachusetts and his colleagues studied sections of the human genome dubbed “human accelerated regions” (HARs). These stretches of DNA are virtually identical in many other mammals that have been studied, suggesting they have important functions – but they differ in humans, implying our evolution has changed them.
Previous studies have identified 3171 possible HARs, but Walsh says it is unlikely that they are all important. “Probably hundreds of them are, but probably not thousands,” he says. His team set out to identify HARs that have played important roles in the evolution of our brains.Advertisement
The researchers placed copies of each HAR, as well as their chimpanzee equivalents, into developing brain cells from mice and humans. In each cell line, they tracked how much each gene in the genome was expressed. This allowed them to determine whether each HAR enhanced the activity of genes, compared with the equivalent sequence from a chimp.

Using this and other methods, the team identified 210 HARs that significantly enhanced gene activity in the neural cells. These HARs probably affect human brain development.
The researchers then zeroed in on a gene called PPP1R17, which is expressed in some of the cells of the developing brain and regulated by several HARs, so it therefore behaves differently in humans than in other mammals. They compared the expression of PPP1R17 in the developing brains of mice, ferrets, rhesus macaques and humans. In the macaques and humans, the gene was expressed in the cerebral cortex, but it wasn’t in the mice and ferrets.
“This gives an example of how dynamic these enhancers are over the course of evolution,” says Walsh.
It isn’t clear why PPP1R17 came to be activated differently in humans, but it may be related to our unusually large brains. Big brains need lots of cells, each of which is likely to contain harmful mutations that need to be fixed. These repairs take time, and PPP1R17 is known to make cells take longer to grow and divide.
Journal reference: Neuron, DOI: 10.1016/j.neuron.2021.08.005
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By Abigail Beall

NASA
Film
The Wonderful: Stories from the space station
Clare Lewins UniversalAdvertisement
OVER 20 years ago, five space agencies representing 15 countries came together to build one of the most ambitious engineering projects the world had ever seen. It took more than 30 missions, with parts manufactured thousands of kilometres apart and assembled by spacewalkers orbiting at 28,000 kilometres per hour, before the International Space Station (ISS) was completed in November 2000.
But The Wonderful – a documentary celebrating the ISS – isn’t an engineering story. It is the story of the people who have made the space station their home in the decades since it was first occupied, and the story of their loved ones back on Earth. Since it was first occupied, there has never been a day when there wasn’t someone living on the ISS.
From the crew who assembled the space station to its most recent inhabitants, this documentary explores the lives of those who have been involved in the ISS since the beginning. Punctuated with music and recordings of Earth from space, the night sky or training facilities, The Wonderful tells the story of the ISS through those who have been most involved with it.
Many of those interviewed dreamed of going into space since childhood, when looking at the night sky sparked their imagination, but it wasn’t always plain sailing. When Ginger Kerrick’s dreams of becoming an astronaut were dashed after NASA discovered she had kidney stones, she instead trained astronauts to prepare for their missions and supported the first crew to fly on the space station – she was there with them until take-off. Astronaut Peggy Whitson spent 10 years applying to become an astronaut until she was finally selected. She went on to spend 665 days in space in her career – more than any other NASA astronaut.
Some didn’t share this childhood dream. Sergey Volkov describes how growing up with his father, the cosmonaut Aleksandr Volkov, made him think going into space was “heroic and difficult”. Many years later, Aleksandr was surprised to learn of his son joining the Russian space agency, Roscosmos, through reading the case files of those selected for the physical assessment.
“In all the years since it launched, there has never been a day when there wasn’t someone living on the ISS”
Pictures and videos can help us understand what it is like to be in space, but nothing quite encapsulates the full experience like hearing it first-hand. In The Wonderful, it is the added details that bring life on the ISS to life. Scott Kelly remarks on the vibrant colours he could see when his vision wasn’t altered by the air, Tim Peake describes the sensation of silence slowly creeping up on him when he made his way into the vacuum of space for his spacewalk, and Samantha Cristoforetti describes seeing the space station up close for the first time.
Behind every astronaut living 400 kilometres above Earth’s surface, there are people on the ground missing them. The Wonderful gives us a glimpse of what it is like when your loved ones are floating above your head. NASA astronaut Cady Coleman’s husband, Josh Simpson, describes hearing from his wife every night, before going outside with their son Jamey to look up and see the ISS whizzing by overhead.
While everyone’s experience of space is different, something that seems to bring those who have been there together is a realisation of how fragile the planet is. A few people in the film mention their surprise at the size of the atmosphere compared with the planet, which Kelly describes as like a contact lens on someone’s eye.
While climate change isn’t explicitly mentioned, it is difficult not to make a comparison between the feat of science and engineering being celebrated in The Wonderful and the challenge facing Earth today. But the story of success that is the space station leaves the viewer with hope that, when working together, humans can do great things.

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By Simon Ings

MRI scans and other tools allow researchers to see our neurological responses to artJOHNNY GREIG/Getty Images
Wonderworks: Literary invention and the science of storiesAngus FletcherSwift Press
NEUROLOGICAL takes on art are fertile ground for a book. In 1999, neurobiologist Semir Zeki published Inner Vision, which explained how different schools of art affect us neurologically – put crudely, Rembrandt tickles one corner of the brain, Mondrian another. Eight years later, Oliver Sacks contributed to an already crowded music psychology shelf with Musicophilia, a collection of true tales in which neurological injuries and diseases are successfully treated with music.Advertisement
Angus Fletcher believes the time has come for literature to get the neurological treatment too. Over the past decade, researchers have used pulse monitors, eye-trackers, brain scanners and other gadgets to look inside our heads as we consume novels, poems, films and comic books. Now these efforts are starting to bear fruit, as he sets out in Wonderworks.
Fletcher’s own experimental work includes a 2016 study into the psychological effects of “free indirect discourse”, a form of narrative that draws attention away from the narrator, instead slipping in and out of characters’ experiences and consciousness. Five literary texts that deal with revenge, including Homer’s Odyssey and Mario Puzo’s The Godfather, were presented in an adapted form to volunteer readers, sometimes as “straight“ stories and at other times written in free indirect discourse. The study found that readers of the latter tales not only offered more empathic responses to a follow-up questionnaire, they also showed a greater understanding of behaviours and moral choices they didn’t identify with.
The claim that reading novels improves theory of mind – the ability to put yourself in someone else’s shoes – has been circulating since the mid-2000s, and has been especially popularised by a team of psychologists at the University of Toronto headed by Keith Oatley. When we are very young, we assume that everyone thinks and feels as we do, but somewhere around our fourth birthday, most of us begin to realise that other people’s heads have their own distinct contents.
Our theory of mind develops as we imaginatively simulate other people’s thoughts. Since stories can present characters’ interiority, might this aid us as we practise and improve our real-life theory-of-mind skills? Research by Oatley and his colleagues has pointed in this direction. Other studies suggest that fiction readers are more social, that romance fiction can make us more empathetic and that fiction can increase the empathy of low-empathy individuals.
Defining technology as “any human-made thing that helps to solve a problem”, Fletcher now jumps several stages further, hypothesising that a story is a suite of narrative-emotional technologies that have helped our ancestors cope with the psychological challenges posed by human biology.
Wonderworks, then, is Fletcher’s scientific history of literature – each of its 25 chapters identifies a narrative “tool” that triggers a traceable, evidenced neurological outcome. Every tool comes with a goofy label: here you will encounter Butterfly Immersers (which push our sense of socially acceptable behaviour, calming the activity of the brain’s medial frontal gyrus) and Stress Transformers (which play on the shared neurological origins of horror and humour).
The book is an intelligent, engaged and erudite attempt to neurologically tackle not just some abstract and simplified “story”, but some of the world’s greatest narratives, from the Iliad to Dream of the Red Chamber, from Disney’s Up to the novels of Elena Ferrante. It speaks to the inner reader in us all, as well as to the inner neurologist.

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In an era of social media cancelling, our nasty side has never been more prominent. But the latest research suggests that, when wielded right, petty ill will can be a force for good

Humans

1 September 2021

By Simon McCarthy-Jones

Ruby Fresson
A MAN buys a house next door to his ex-wife and installs a 4-metre bronze statue of a hand, middle finger raised, facing her window. A prominent investor buys a company so he can fire the management he dislikes, even though he stands to lose money. People take their time at the checkout to annoy the next customer, buy gnomes for their garden to antagonise a neighbour and slow down to annoy tailgaters, even though it puts everyone in danger.
Examples of spiteful behaviour, harming another at some cost to yourself, aren’t hard to find. As a psychological game where no one wins, spite is puzzling: we may wonder why it wasn’t weeded out by evolution long ago. Instead, in a competitive era of identity politics, all too often played out on social media, it seems more prevalent than ever.
Yet, compared with other social behaviours like selfishness, cooperation and altruism, there has been relatively little psychological research into why we do it. With potentially far-reaching consequences for both political stability and individual mental health, it has never been more important to understand this dark side of human behaviour.
For many years, most of the research into spite came from the field of behavioural economics: the study of how human decision-making differs from what you would expect from a purely rational point of view. Classical economists dreamed up the concept of Homo economicus, a person who only ever acts to maximise their own rewards. If offered a choice between something and nothing, Homo economicus would always take what is on offer.
In experiments, however, this isn’t how everyone behaves. In … More

By Michael Marshall

The Actual Star culminates in Actun Tunichil Muknal in Belizemauritius images GmbH/Alamy
The Actual Star: A novel
Monica Byrne
Harper VoyagerAdvertisement

WITH her second novel, author Monica Byrne has pulled out all the stops. The Actual Star was eight years in the making. It has three storylines, separated by millennia: one is set 1000 years ago in a declining Mayan kingdom, one in 2012 and one in a distant future shaped by catastrophic climate change. The seemingly disparate stories are rapidly revealed to be linked.
When a book is this ambitious, either it is a thumping success or it falls on its face. Happily, The Actual Star is a stone-cold masterpiece. It is one of the most moving novels I have read and surely a contender for major awards.
The first thing that struck me was how immediately immersive the three stories are. The ancient Mayan storyline follows three young members of a royal family: Ajul, Ixul (the “x” is pronounced “sh”) and Ket. Byrne keeps the story tightly focused on their perspectives. She has a tricky tightrope to walk because the characters use human sacrifice to solidify their political power, and Ajul and Ixul have incestuous sex. Yet Byrne shows their motivations and makes them sympathetic, without unduly softening them.
“The Actual Star is a stone-cold masterpiece. It’s one of the most moving novels I have read”
The middle timeline follows a young woman named Leah from Minnesota, who travels to Belize on a journey of self-discovery: her late father was from there, but she never met him and is in search of her identity and heritage. Byrne finds great depth and nuance in this story, never falling into the trap of exoticising the Belizean culture. It helps that some chapters are told from the perspectives of two Belizean tour guides, Xander and Javier, so we get to see Leah through their eyes.
The futuristic sections follow Niloux deCayo, who finds herself labelled a heretic when she dares to challenge her society’s beliefs. Byrne’s version of the future is richly imagined. In response to devastating sea level rise and extreme weather, humanity has adopted a nomadic existence. Nobody is allowed to stay in the same place for more than a few days.
Acquiring possessions beyond what is absolutely necessary is condemned as “hoarding”: these future people look back on our consumer era with horror. Byrne imagines a swathe of new social rules, an entire political system based on decentralised technologies like blockchain and, crucially, a new religion.
It is in the religion that the three timelines link. Byrne’s futuristic theology is based on Mayan beliefs, specifically the idea of Xibalba: an underworld ruled by gods of death.
But this version of Xibalba is a place where people can finally perceive the world as it truly is, without the filters and concepts imposed by our sense organs and brains – to comprehend “the thing-in-itself”, as the philosopher Immanuel Kant put it. Or as Ixul thinks at one point: “The star we see is not the actual star.” In all three timelines, characters converge on the cave of Actun Tunichil Muknal in Belize where this transcendent perception may be possible.
If this all sounds like a lot, it is, but the book is perfectly paced: it is leisurely enough to let you get to know the people and grasp the heady concepts, but there is constant forward momentum and a steady crescendo. The climax is as dramatic as anyone could wish for, but for me the real joys of The Actual Star are the vivid characters and societies. It is a book that will resonate with me for a long time.

Michael also recommends…
Film
Nomadland
A more contemporary take on nomadic life, Chloé Zhao’s beautiful film follows Frances McDormand’s Fern around the US in search of work following the 2008 economic crisis.
TV
Loki
Disney+
The latest Marvel series is a riot of invention that fuses time travel, multiple universes and a cosmic bureaucracy – even if the finale is a bit of a let-down.

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By Michael Marshall

The Nefud desert in northern Saudi Arabia, which humans have inhabited during periods of increased rainfallCeri Shipton
Ancient humans repeatedly entered the Arabian peninsula from Africa during the past 400,000 years. A single archaeological site in Saudi Arabia holds evidence of five separate occupations, according to a new study.
A second study suggests that each out-of-Africa migration was made possible by a shift to a wetter climate, creating green corridors. It simulated changes in the region’s climate over the past 300,000 years, and found that there were several periods when conditions … More