Humans

According to the laws of physics, everything we do follows inevitably from what happened before – and yet we’re convinced we can change the world. Can we?

Humans 9 December 2020
By Richard Webb
If you don’t want to read this, put the magazine down now
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Are you predetermined?
WHAT are you doing right now? Reading these words. Why? Presumably because you chose to. Even if you didn’t – if you are encountering them years in the future lining a forgotten box of crockery in the attic, say – you can always choose to look away now. You possess the nebulous quality of human free will.
Nebulous because, despite debating it for millennia, philosophers have been unable to pin it down – and although we are pretty convinced we have it, at some level it must be an illusion, rather like our sense of self is (see “Are you always the same person?”).
Let’s start with the physics. Whenever you decide something, a certain pattern of neurons fires in your brain to turn your thought into action – moving towards the kitchen to make coffee, perhaps, or formulating an utterance you will come to regret. Ultimately, that is all down to pulses of electrons – fundamental particles that follow the cast-iron laws of physics, under which everything is determined by what happened immediately before.
That doesn’t leave much room for free will, apparently. “Physical laws, if they’re deterministic, tell me that everything that I do, everything that happens in the world, including everything that I do, including every decision I ever made, follows logically from the laws of nature [and] the initial conditions of the universe,” says philosopher of physics Jenann Ismael at Columbia University in New York. Since we control neither the laws of nature nor the initial conditions of the universe, we … More

It’s easy to be disheartened by the puniness of our existence – yet perhaps for the first time in human history, everything depends on decisions each one of us makes

Humans 9 December 2020
By Joshua Howgego

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Do you matter?
LET’S start with the big picture: if it is significance on this Earth you are looking for, then the numbers are increasingly against you.
Go back 2000 years and there were fewer than 200 million people on the planet. When the industrial revolution kicked in from the 18th century, however, new methods emerged of feeding vastly more people and combating the infectious diseases that had kept our numbers in check. Our numbers began to shoot up, reaching nearly 7.7 billion now. Today, you are, to a greater extent than in all history, just a face in a crowd.
That doesn’t mean you matter any less to your closest friends and family. And perhaps you or your offspring may be one of those few who change the world for better (or for worse). But that is statistically unlikely. Even in spheres where we like to think we are important, such as parenting, the evidence suggests individuals don’t matter that much. Geneticist Robert Plomin at King’s College London has pointed out, for instance, that identical twins brought up in different families generally end up with the same level of cognitive ability.
It isn’t just about you
But there is another, contrary, line of thinking, that collectively all of us can make a difference on a grand scale. In the broad sweep of human history, these are pivotal times. With the development of nuclear weapons in the mid-20th century, humanity reached a point where we can destroy ourselves. In this century, existential risks have only increased thanks to the threat of catastrophic climate change, … More

Covid-19 continues to split some people along party lines. We are now beginning to work out why, writes Graham Lawton

Humans | Comment 9 December 2020
By Graham Lawton

REUTERS/Mike Blake

LIKE the majority of people in my local area, I follow the rules on face coverings. It’s an inconvenience, but I consider putting on a mask a small sacrifice to protect my health and that of other people. Every day, I see many people – more than could possibly have a legitimate exemption – flagrantly flouting the rules and it really gets up my nose.
The refuseniks annoy me on multiple levels. They are selfishly putting me and other people at risk. They think they know better than experts. They often fall for conspiracy theories. And even if they are … More

According to the many-worlds interpretation of quantum mechanics, the universe is constantly dividing and taking you with it – so would you recognise your other selves if you met them?

Humans 9 December 2020
By Daniel Cossins

Jonathan Knowles/Getty Images

Is there more than one of you?
BIOLOGICALLY speaking, there is definitively only one you (see “How likely are you?”). Physics might give you pause for thought, however. The most bewildering argument against your uniqueness comes from quantum mechanics, the fundamental theory that describes the often counter-intuitive behaviour of subatomic particles. It might imply not only that there are multiple, identical versions of you, but even that there are an infinite number of yous out there.
The quantum realm is notoriously fuzzy: quantum objects such as particles are described in terms of probabilities, encoded in mathematical widgets called wave functions that give you the odds on any number of different states the object might be in. Only when you observe or measure it does the object take on one of those states, at least from your perspective.
“Quantum theory might imply there are an infinite number of yous out there”
The truth of what happens at this point – and indeed what, if anything, the wave function itself is trying to tell us about reality – divides physicists. Many stick with a cop-out known as the Copenhagen interpretation: essentially, that we can never know what is happening in this fuzzy pre-measurement realm. In other words, quantum theory makes predictions about reality, but says nothing about what goes on under the hood.
That isn’t good enough for some. Physicists who subscribe to the rival “many worlds” interpretation insist that all the possibilities encoded in the wave function are real, and that they continue to exist in different universes that split off from ours every time a quantum … More

Quantum information can never be destroyed, so some of the essence of you could live on after death – but it’s not going to help the physical you

Humans 9 December 2020
By Joshua Howgego
Is death the end, or does part of us live on?
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What happens when you die?
MICHELLE FRANCL-DONNAY will never forget 15 April 1987. Her husband Tom was due to pick her up from an evening meeting, but decided to take a swim first. He had an undiagnosed heart condition, and while in the pool had a catastrophic aneurysm. Michelle rode with him in the ambulance. That was the last time she spoke to him.
“When I saw Tom’s body the next morning, he clearly wasn’t there anymore,” says Francl-Donnay, a chemist at Bryn Mawr College in Pennsylvania and an adjunct scholar at the Vatican Observatory who writes extensively on both science and spirituality. Over the years, she found herself mulling a question humans have asked for a long time: where had he gone?
Even those of us who rationally reject the idea of an afterlife have trouble letting go of the idea. That might be down to our theory of mind. Because we habitually put ourselves in other people’s shoes and imagine their thoughts and feelings, it can be hard to believe that those thoughts and feelings can just cease to be when ours still feel so real.
Yet we have no evidence for anything different. When you die, blood stops flowing, the muscles cool and consciousness, whatever that is, slips away. If your body were simply let be, other organisms would rapidly digest it, from microbes already living inside you to newly arrived blowflies.
Human burial rites just change the timescale or manner of your physical disappearance: if your remains are cremated, for instance, the … More

By Claire Ainsworth

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LARS IGUM RASMUSSEN and his mates were going large. Donning their lederhosen, the three middle-aged men headed into Oktoberfest in Munich, Germany, the world’s biggest folk and beer festival. There, each proceeded to quaff an average of 7.5 litres of beer a day, for three days. It was a spectacular bender.
Getting hammered wasn’t the main aim of the exercise, however: Rasmussen is health correspondent for Danish magazine Politiken and was writing a story exploring the physiological effects of binge drinking. To understand what was happening to him and his friends, he had enlisted the help of metabolic physiologist Filip Knop at the University of Copenhagen. While Rasmussen was interested in finding out what havoc excessive boozing wreaks on the bodies of middle-aged men, Knop had another motive for getting involved. He and his colleague Matt Gillum had been itching to test a new idea about people’s appetite for alcohol – but couldn’t, in good conscience, solicit anyone to partake in a binge of this magnitude. “It would give the ethics officer a heart attack,” says Gillum. Volunteers, however, were a different matter.
What Knop and Gillum discovered is helping to build a picture of how our bodies control our boozing habits, from the amount we drink to when we stop. The research is homing in on a hormone that partly explains the huge variation in our social drinking habits: why some people are teetotal or can’t drink much, while others are lushes. It also points to the startling idea that our livers have more say in directing our behaviour than anyone imagined.
Of course, people choose to … More

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