Humans

By Claire Ainsworth

Matt Cardy/Getty Images

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

How do humans feel living in a world where robots outperform them, asks The Preserve by Ariel S. Winter. Clare Wilson says it’s a great thought experiment

Humans 9 December 2020
By Clare Wilson
How would we react if machines dominated the world?
Donald Iain Smith/Getty Images

The Preserve
Ariel S. Winter
Simon & Schuster
WHEN AI that is truly sentient finally emerges, the big question is how humans will fare. Will machines try to hunt us to extinction, as in the Terminator films, or will their omnipotence mean life for humans can be the kind of extended party of Iain M. Banks’s Culture series?
In Ariel S. Winter’s The Preserve, the robots have reached a stage somewhere in the middle. The book is set in the not-too-distant future, when human populations have dwindled … More

Gary Ellis Photography/Alamy
“KNOW thyself.” The first of three maxims said to have been inscribed in the forecourt of the Temple of Apollo in Delphi sounds grand. What it actually means has been a matter of debate for millennia, and when it comes to knowing ourselves, modern science has made things deliciously more complex, too.
How the physical substance of our bodies creates our sense of being a consistent entity, and what it means to have that sensation, is a long-standing puzzle. Debates about this relationship between matter and mind were meat and drink to the Ancient Greek philosophers, but … More

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

“Know thyself” is a piece of wisdom handed down from the ancients – but a slew of delusions and biases means you might be better off asking someone else

Humans 9 December 2020
By Alison George
The delusional Don Quixote and his faithful squire Sancho Panza in the 2018 film The Man Who Killed Don Quixote
Alamy Stock Photo

Can you ever truly know yourself?
DON QUIXOTE is one of the most celebrated characters in literature. The hero of Miguel de Cervantes’s novel, first published in 1605, decides to act out his knightly aspirations, performing acts of great chivalry and righting wrongs. So he thinks, anyway. Sadly, the gulf between his self-perception and how the world views him is vast – so much so that the word “quixotic” has come to describe delusional behaviour.
But here is a troubling thought. What if we are all more quixotic than we allow for? We might think that with our privileged access to our every thought and motivation, we are the best judge of our own character, but what if we aren’t?
In recent decades, psychologists have revealed that we are beholden to all sorts of biases and mental blind spots that put a positive spin on our characters. In one study from the 1960s of drivers hospitalised by car accidents, for instance, all judged their driving ability to be better than average.
This “illusory superiority” bias has been demonstrated many times since. Indeed, it turns out that the worse we are at a particular task, the less likely we are to recognise our own incompetence – something known as the Dunning-Kruger effect. And we are crashingly unaware of all of this: while we recognise the impact of bias in other people’s judgements, we miss it in our own.
It isn’t all bad news though. In a seminal study a decade … More

Most of us instinctively think that our sense of self is located in our head – but experiments show that our brains aren’t working alone in creating our sense of self

Humans 9 December 2020
By Alison George

Martin Parr/Magnum Photos

Where is your self?
FOR the Ancient Egyptians, it was the heart. For philosopher René Descartes, it was somewhere entirely separate from the body. According to the Buddhist concept of anatta, it isn’t anywhere, because the thing concerned doesn’t exist.
But what does modern science say about where your self – your “soul”, if you like – resides?
At first pass, that might not seem a particularly scientific question. Regardless, most of us have an intuitive answer. When, in as-yet unpublished work, Christina Starmans and her colleagues showed people from the US and India pictures of flies circling around a person, and asked which flies they thought were closest, the results were striking: regardless of cultural background, most people pointed to flies near a person’s eyes. “This suggests there is a universal sense of the self being located in the head, near the eyes,” says Starmans, a psychologist at the University of Toronto in Canada.
Subjectively at least, the eyes being windows to the soul checks out. “The sense of where in our bodies we are located is informed by our dominant experience of the world,” says Starmans. “Almost all of our input from the world comes in through our head.”
What our heads do with these inputs is certainly incredible, and key to our feeling that we are coherent beings. Our brains take a hotchpotch of electrical messages from our sense organs – eyes, ears, nose, skin – and combine them with memories to create a vivid, unified sense of conscious experience that is continuous in time.
How exactly this happens is still something of a mystery. But … More

We have a strong sense of continuous, coherent existence – yet from the cells that make our bodies to our defining character traits, we are in a constant state of change

Humans 9 December 2020
By Tiffany O’Callaghan
Each of us shows many differing faces over time
Getty Images

Are you always the same person?
MY MOM sometimes jokes that it is fortunate she didn’t meet my dad when he was in college, because she wouldn’t have liked him. She was (and is) a self-described goody two shoes. Dad not so much, but presumably even less so when keg parties were involved.
We know that we change over time. Our bodies grow, then age; we mature and our views shift; our memories sharpen and fade. Yet for most of us, our sense of self is seamless and continuous. You are the same old you, right?
Let’s start with the physical. Some of our cells, notably neurons in the brain, are with us from before birth, and can live more than 100 years. “Most of the nerve cells in the brain are actually as old as we are,” says molecular biologist Jonas Frisén at the Karolinska Institute in Sweden.
But most of our cells aren’t. Some, including certain kinds of white blood cell, live for only days. How quickly our skin cells are replenished changes as we age, but in general it takes about a month. The notion that the liver regenerates every 40 days or so is a myth: our liver cells live 200 to 300 days.
On the level of atoms and molecules, meanwhile, we are exchanging material with our environment with abandon. Think of your body like a grassy field, says Frisén. “It’s the same lawn from year to year, but each strand of grass is completely different.”
But what about less tangible … More