Humans

We’re slowly beginning to unpick the complex interplay of genes, environment and experience that make you who you are – and like no one else who ever existed

Life 9 December 2020
By Clare Wilson
Birth is only a waymarker on the road to becoming you
Kieferpix/Getty Images

How likely are you?
CHILDREN are generally fascinated by tales of how they came to be. Even young ones can often grasp the mind-boggling implication if the events of the story leading up to their existence had been any different: they wouldn’t be there to hear it.
Your you-ness is a precarious thing. Rerun the experiment of you with a different sperm and egg from the same people, and “you” would be as different from your current self, genetically, as siblings are from one another. If the egg were the same, but through some random fluctuation a different sperm won the race, you would also be distinctly different. For a start, depending on whether the sperm bore an X or a Y chromosome, you could have ended up another sex. “That’s a pretty big difference, right there,” says David Linden, a neuroscientist at Johns Hopkins University in Maryland and author of Unique: The new science of human individuality.
The potential for being a different you didn’t stop once destiny set your founding sperm and egg on their collision course, either. A lot of what makes you what you are is down to how your brain is connected. But your DNA doesn’t encode a precise wiring diagram: it is more like a rather hand-wavy recipe or set of instructions. Even genetically identical twins don’t end up with the same neuronal network. “A pool of cells in the developing brain might receive instructions that say: ‘About half of you move across the midline of the brain’, ” says Linden. “In one twin, 40 per … More

The point when you began depends on the scale you look at and how you define a person – in one sense you’re as old as the universe, in another you’ve hardly begun at all

Humans 9 December 2020
By Daniel Cossins
Arguably, you only become a person when you can reflect on other people’s view of you
Daisuke Takakura

When did you begin?
YOU almost undoubtedly know the date, possibly even the hour, you were born. Whether you are past celebrating rather depends. But reflect on the big picture, and the truth about when you began is too epic, and possibly a little too confusing, to be captured by a terse entry on a birth certificate.
That story begins in the deep cosmos. As anyone with a passing interest in Joni Mitchell’s back catalogue knows, we are stardust. It’s a nice line, and it also happens to be true, says Karel Schrijver, an astrophysicist at the Lockheed Martin Advanced Technology Center in California.
Most of your body’s trillions of atoms, from calcium in your bones and carbon in your genes to iron in your blood, were forged by nuclear reactions in ancient stars, either when they were burning or when they ended in fiery supernova explosions. Those atoms were recycled through the births and deaths of more stars until, at some point, they escaped for a while. “Our solar system captured these elements to make Earth and everything on it,” says Schrijver – including you.
In that sense, we can’t know exactly when we began: it depends how many generations of stars our atoms cycled through. But each of us is at least 4.6 billion years old, the age of the solar system, and perhaps as ancient as the universe’s first stars, which appeared some 13.7 billion years ago, just 100 million years after the big bang. The hydrogen within … More

By Colin Barras
Living in darkness, or even hibernating, could have left ancient humans with bone lesions
gorodenkoff/Getty Images

Some of the ancient humans living in Europe half a million years ago had a remarkable strategy for dealing with winter: they hibernated. At least, that is the claim being made by two researchers. Others dispute the evidence – but ongoing research suggests that it might be possible to induce a hibernation-like state in modern humans.
Sima de los Huesos – the “pit of bones” – lies in northern Spain and is one of the world’s most important sites for studying human evolution. Excavations at … More

By Luke Taylor
The rock art may be 12,500 years old
Courtesy of Jose Iriarte

An extensive collection of ancient rock art and archaeological remains found deep in the Colombian Amazon offers a rare glimpse into the lives of the earliest people to inhabit the region.
The images and remains suggest that people lived in the northern Amazon at the same time as now-extinct mega-mammals. They also show that the ancient humans had a varied diet, indicating that they adapted quickly to their new environment.
The as-yet unnamed site in the Serranía La Lindosa, a large, rocky outcrop in southern Colombia, was found by an international team of researchers investigating the Guaviare region. It is the earliest secure evidence of people in the Colombian Amazon, they say.

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A wealth of Indigenous artwork has been documented across Guaviare, particularly in Chiribiquete National Park. The artwork documented at La Lindosa is new to science, and appears to be unknown even to local people, according to the researchers. It is remarkable in both its detail and its scale, the team says. The collage of images includes geometric patterns, handprints, people and animals. It stretches across approximately 5 kilometres of rock face, and could take decades to fully study.

The archaeological team – co-led by Francisco Javier Aceituno at the University of Antioquia, Colombia – was thrilled to find depictions of what appear to be now-extinct megafauna alongside more familiar fish, birds and lizards still alive today.
“We knew that megafauna was in the region and went extinct around 10 to 12,000 years before the present,” says José Iriarte at the University of Exeter, UK, and a member of the research team. If people were depicting them in their art, the humans must have been present in the region at least 12,500 years ago, he argues.
Iriarte says it is “quite clear” that a palaeolama, an extinct stumpy-legged, long-necked camelid, is depicted. Other drawings have been tentatively identified as giant sloths due to their unique proportions, and mastodons – ancient relatives of elephants – due to their trunks.
“The realism for South American standards is really impressive,” says Iriarte.

Others are less sure.
“The horses are clear,” says Hans ter Steege, an expert on Amazonian plant diversity at the Naturalis Biodiversity Center in the Netherlands, who wasn’t involved in the research. “But the palaeolama could be a poor representation of a deer to me.”
Further study will be made of the artwork to gain more certainty of the depictions and their age, say the researchers.

However, additional archaeological evidence makes clear that humans were present in the region 12,500 years ago. The researchers have excavated an area at the base of one section of rock face and uncovered evidence of ancient human activity in the form of processed animal bones. Some of the remains occur in layers of dirt containing charred palms that radiocarbon dating shows are about 12,500 years old. The 12,500-year-old layers also contain fragments of ochre similar to that used to draw the rock art.
Establishing the presence of humans during this period — in which megafauna roamed the region and the climate was warming — is significant, says Aceituno.
“The most important thing has been to obtain good radiocarbon dates to specify the early peopling of the area,” he says.
It shows that humans shared the region with immense beasts, but also helps paint a picture of how their world would have looked.
No megafauna remains have been found at the site, perhaps suggesting that humans didn’t hunt the animals or they were processed elsewhere. There were no remains of medium-sized animals like monkeys either, a staple food for Indigenous groups inhabiting the region today. “It could mean they had not developed blowgun technology at this stage to hunt prey in the treetops,” says Iriarte.
Around half the remains were fish — including piranhas — but diets were broad. Reptiles like iguanas and snakes were consumed as well as rodents like paca and capybara.
There is also evidence that various fruits were eaten. The diversity of animals and plants consumed suggests humans adapted quickly to the Amazon, says ter Steege.
Journal reference: Quaternary International, DOI: 10.1016/j.quaint.2020.04.026
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By Donna Lu
Archaeologists have built replica Stone Age rafts to attempt the crossing to the Ryukyu islands
Yosuke Kaifu

Stone Age humans crossed the sea from Taiwan to the Ryukyu islands of south-west Japan tens of thousands of years ago – and it looks like they did so deliberately, even though the islands are too far away to be reliably visible from Taiwan.
Archaeological sites on several of the Ryukyu islands suggest humans had reached the islands by about 30,000 to 35,000 years ago. Yosuke Kaifu at the University of Tokyo and his colleagues suspect the ancient people did so by travelling north-east from Taiwan – a journey that involved ocean crossings of tens to hundreds of kilometres to hop from island to island. The researchers have even repeated some of these ocean crossings themselves using bamboo rafts of the kind that Stone Age humans might have built.
But it hadn’t been clear whether the crossing occurred deliberately or by accident. The Kuroshio current, which flows from Luzon in the Philippines past Taiwan and Japan, is one of the strongest ocean currents in the world, and in some parts is 100 kilometres wide.

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“The speed of the Kuroshio in the east of Taiwan is normally 1 to 2 metres per second,” says Kaifu.

To find out if people could have arrived at the islands by drifting on this current, the researchers looked at existing data from 138 satellite-tracked buoys, released into the world’s oceans as part of the Global Drifter Program. The 138 buoys all drifted past Taiwan or Luzon between 1989 and 2017.
Kaifu and his colleagues found that only four buoys travelled to within 20 kilometres of any of the Ryukyu islands. In all four cases this occurred as a result of adverse weather conditions, including a typhoon.
The finding suggests that the Kuroshio current directs drifters away from, rather than towards, the Ryukyu islands. Because the flow of the current is thought to have stayed the same for the past 100,000 years, it seems likely that Stone Age people reached the Ryukyu islands through deliberate voyaging rather than accidental drifting.
“Now we can tell with confidence that Palaeolithic people set sail deliberately even to a remote invisible island,” says Kaifu.

“Most people probably think that Palaeolithic people were just primitive and conservative, but I now see something different from that general image,” he says.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-020-76831-7
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From The End of Everything by Katie Mack and How to Argue with a Racist by Adam Rutherford to Martha Wells’s Murderbot sc-ifi series, New Scientist’s 2020 gift guide has a book for everyone

Humans 2 December 2020
By New Scientist

Getty Images/Westend61

The End of Everything (Astrophysically Speaking)
by Katie Mack
For a bit of seasonal giving, why not look to the end of the universe? Thankfully, The End of Everything (Scribner) by Katie Mack is no apocalyptic vision but an engrossing and often funny tour of all the ways our cosmos might come to a close. Mack’s enjoyment of physics stands out – and is contagious. She describes primordial black holes as “awfully cute in a terrifying theoretical kind of way”, antimatter as “matter’s annihilation-happy evil twin” and the universe as “frickin’ weird”. All true, and Mack’s explanations … More

In Watch Dogs: Legion you can play as or team up with any of the characters of the game, and strolling around its digital version of London is a real treat, says Jacob Aron

Humans 2 December 2020
By Jacob Aron
Key London landmarks like The Shard appear in Watch Dogs: Legion
Ubisoft

Watch Dogs: LegionUbisoftPC, PlayStation 4 and 5, Xbox One, Series X and S
NEW SCIENTIST closed its offices on 13 March, a week or so before the UK went into national lockdown. Since then, I have spent most of this year in a small radius around my north London flat and have been into the city centre only a handful of times.
As a native Londoner, it is strange to be so cut off from the city, which is why the opening moments of Watch … More

Lockdown restrictions in winter might seem something to dread, but we can combat this by embracing the mindset of people used to long, dark winters, says health psychologist Kari Leibowitz

Health 2 December 2020
By Kari Leibowitz

Rocio Montoya

WHEN health psychologist Kari Leibowitz moved from the US to the Norwegian town of Tromsø, more than 300 kilometres north of the Arctic circle, her research became personal. Inspired by recent findings on the ways in which people’s attitudes influence their mental and physical health, she wondered whether this might be the secret to coping with the long, dark Nordic winter. Her research revealed that many Norwegians have a winter mindset that allows them to thrive in conditions she was dreading. Now back in the US at Stanford University, Leibowitz believes her findings hold lessons for us all, especially for people living in the northern hemisphere who, as the nights draw in, face the dual challenges of winter and a stressful pandemic.
David Robson: What are “mindsets” and why are they so important?
Kari Leibowitz: I think of mindsets as a framework that helps us simplify information and make sense of the world. And we’re really just at the beginning of unpacking the ways that they can shape our health and well-being.
A lot of my research now is looking at how we can use mindsets in clinical practice. In one of the last studies that I did, we tested the effects of changing people’s mindsets – even without treatment. We brought our participants to the lab and we pricked them with histamine, triggering a minor allergic reaction that looks a bit like a mosquito bite. For some people, a doctor just examined their arm; for the others, the doctor examined their arm and said: “OK, from now on, the itch and irritation will feel better and your … More