Can Humans Ever Understand How Animals Think?

 

A flood of new research is overturning old assumptions about what animal minds are and aren’t capable of – and changing how we think about our own species

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Giraffes will eat courgettes if they have to, but they really prefer carrots. A team of researchers from Spain and Germany recently took advantage of this preference to investigate whether the animals are capable of statistical reasoning. In the experiment, a giraffe was shown two transparent containers holding a mixture of carrot and courgette slices. One container held mostly carrots, the other mostly courgettes. A researcher then took one slice from each container and offered them to the giraffe with closed hands, so it couldn’t see which vegetable had been selected.

In repeated trials, the four test giraffes reliably chose the hand that had reached into the container with more carrots, showing they understood that the more carrots were in the container, the more likely it was that a carrot had been picked. Monkeys have passed similar tests, and human babies can do it at 12 months old. But giraffes’ brains are much smaller than primates’ relative to body size, so it was notable to see how well they grasped the concept.

Such discoveries are becoming less surprising every year, however, as a flood of new research overturns longstanding assumptions about what animal minds are and aren’t capable of. A recent wave of popular books on animal cognition argue that skills long assumed to be humanity’s prerogative, from planning for the future to a sense of fairness, actually exist throughout the animal kingdom – and not just in primates or other mammals, but in birds, octopuses and beyond. In 2018, for instance, a team at the University of Buenos Aires found evidence that zebra finches, whose brains weigh half a gram, have dreams. Monitors attached to the birds’ throats found that when they were asleep, their muscles sometimes moved in exactly the same pattern as when they were singing out loud; in other words, they seemed to be dreaming about singing.

In the 21st century, findings such as these are helping to drive a major shift in the way human beings think about animals – and about ourselves. Humanity has traditionally justified its supremacy over all other animals – the fact that we breed them and keep them in cages, rather than vice versa – by our intellectual superiority. According to Aristotle, humans are distinguished from other living things because only we possess a rational soul. We know our species as Homo sapiens, “wise man”.

Yet at a time when humanity’s self-image is largely shaped by fears of environmental devastation and nuclear war, combined with memories of historical atrocity, it is no longer so easy to say, with Hamlet, that man is “the paragon of animals” – the ideal that other creatures would imitate, if only they could. Nature may be “red in tooth and claw”, but creatures whose weapons are teeth and claws can only kill each other one at a time. Only humans commit atrocities such as war, genocide and slavery – and what allows us to conceive and carry out such crimes is the very power of reason that we boast about.

In his 2022 book If Nietzsche Were a Narwhal, Justin Gregg, a specialist in dolphin communication, takes this mistrust of human reason to an extreme. The book’s title encapsulates Gregg’s argument: if Friedrich Nietzsche had been born a narwhal instead of a German philosopher, he would have been much better off, and given his intellectual influence on fascism, so would the world. By extension, the same is true of our whole species. “The planet does not love us as much as we love our intellect,” Gregg writes. “We have generated more death and destruction for life on this planet than any other animal, past and present. Our many intellectual accomplishments are currently on track to produce our own extinction.”

If human minds are incapable of solving the problems they create, then perhaps our salvation lies in encountering very different types of minds. The global popularity of the documentary My Octopus Teacher, released by Netflix in 2020, is just one example of the growing hunger for such encounters. In the film, the South African diver Craig Foster spends months filming a female octopus in an underwater kelp forest, observing most of her lifecycle. Foster presents himself as the anti-Jacques Cousteau; he doesn’t go underwater to study the non-human, but to learn from it.

Humility is a traditional religious discipline, and there is a spiritual dimension to Foster’s quest and to the film’s success. On YouTube, where the trailer has been viewed 3.7m times, thousands of people testify that My Octopus Teacher made them weep, changed their understanding of the world and made them resolve to lead better lives. It’s clear that, for modern people who seldom encounter animals except for pet cats and dogs, entering into a close relationship with a non-human mind can be a sacred experience.

The idea of the octopus as the nonhuman mind par excellence was popularised by the 2016 bestseller Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness, by Peter Godfrey-Smith. A philosopher rather than a marine biologist, Godfrey-Smith got an opportunity to see the creatures in action at a site off eastern Australia known to researchers as Octopolis. There he discovered that octopuses are “smart in the sense of being curious and flexible; they are adventurous, opportunistic”, prone to making off with items such as tape measures and measuring stakes.

The fascination of the octopus is that while its behaviour seems recognisable in human terms as mischief or curiosity, its neural architecture is immensely different from ours. Since Darwin, humans have grown used to recognising ourselves in our fellow primates, whose brains and body plans are similar to our own. After all, humans and chimpanzees share a common ape ancestor that lived in Africa as recently as 6m years ago. Our most recent common ancestor with the octopus, by contrast, is a worm-like creature thought to have lived 500-600m years ago.

Because the mind of the octopus evolved in a completely different fashion from ours, it makes sense of the world in ways we can barely imagine. An octopus has 500m neurons, about as many as a dog, but most of these neurons are located not in the brain but in its eight arms, each of which can move, smell and perhaps even remember on its own. In Godfrey-Smith’s words, an octopus is “probably the closest we will come to meeting an intelligent alien”. When such a being encounters a human at the bottom of the ocean, what could it possibly make of us?

For most of the 20th century, animal researchers wouldn’t even have asked such a question, much less attempted to answer it. Under the influence of the American psychologist BF Skinner, scientific orthodoxy held that it was neither legitimate nor necessary to talk about what was going on in an animal’s mind. Science, he argued, only deals with things that can be observed and measured, and we can’t directly observe mental faculties even in ourselves, much less in animals. What we can observe is action and behaviour, and Skinner was able to modify the behaviour of rats using positive reinforcement, such as rewards of food, and negative reinforcement, such as electric shocks.

 When Jane Goodall first went to study chimpanzees in Tanzania in the 1960s, the very notion of animal subjectivity was taboo. Her practice of giving names to the individual chimps she observed – such as David Greybeard, who her studies made famous – was frowned on as unscientific, since it suggested that they might be humanlike in other ways. The standard practice was to number them. “You cannot share your life with a dog or a cat,” Goodall later observed, “and not know perfectly well that animals have personalities and minds and feelings. You know it and I think every single one of those scientists knew it, too, but because they couldn’t prove it, they didn’t talk about it.”

Today, the pendulum has swung in the other direction. Scientists speak without embarrassment about animal minds and consciousness. In popular writing on the subject, Skinner appears only as a villain. In his 2016 book Are We Smart Enough to Know How Smart Animals Are?, primatologist Frans de Waal discusses a mid-20th-century experiment in which researchers at a primate centre in Florida, educated in Skinner’s methods, tried to train chimps the way he had trained rats, by withholding food. “Expressing no interest in cognition – the existence of which they didn’t even acknowledge,” De Waal writes, the researchers “investigated reinforcement schedules and the punitive effect of time-outs.” The staff of the primate centre rebelled and started feeding the chimps in secret, causing Skinner to lament that “tender-hearted colleagues frustrated efforts to reduce chimpanzees to a satisfactory state of deprivation”. You could hardly ask for a better example of how the arrogance of reason leads to cruelty.

Meanwhile, animals without “rational souls” are capable of demonstrating admirable qualities such as patience and self-restraint. Among humans, the ability to sacrifice immediate pleasure for future gain is called resisting temptation, and is taken as a sign of maturity. But De Waal shows that even birds are capable of it. In one experiment, an African grey parrot named Griffin was taught that if he resisted the urge to eat a serving of cereal, he would be rewarded after an unpredictable interval with food he liked better, such as cashew nuts. The bird was able to hold out 90% of the time, devising ways to distract himself by talking, preening his feathers, or simply throwing the cup of cereal across the room. Such behaviours, De Waal notes, are quite similar to what human children do in the face of temptation.

More intriguing than the convergences between human and animal behaviour, however, are the profound differences in the way we perceive and experience the world. The reason why an encounter with an octopus can be awe-inspiring is that two species endowed with different senses and brains inhabit the same planet but very different realities.

Take the sense of smell. As humans, we learn about our surroundings primarily by seeing and hearing, while our ability to detect odours is fairly undeveloped. For many animals, the reverse is true. In his 2022 book An Immense World, the science journalist Ed Yong writes about an experiment by researcher Lucy Bates involving African elephants. Bates found that if she took urine from an elephant in the rear of a herd and spread it on the ground in front of the herd, the elephants reacted with bewilderment and curiosity, knowing that the individual’s distinctive odour was coming from the wrong place. For them, a smell out of place was as fundamental a violation of reality as a ghostly apparition would be for us.

  Animals that perceive the world through scent, such as dogs, even have a different sense of time. We often talk about the importance of “living in the moment”, but in fact we have no other choice; since visual information reaches us at the speed of light, what we see around us are things as they existed an infinitesimal fraction of a second ago. When a dog smells, however, “he is not merely assessing the present but also reading the past and divining the future”, Yong writes. Odour molecules from a person or another dog can linger in a room long after the source is gone, or waft ahead before it appears. When a dog perks up long before its owner walks through the front door, smell can seem like a psychic power.

If giraffes can do statistical reasoning and parrots understand the concept of the future, then where does the distinctiveness of the human mind really lie? One favourite candidate is what psychologists call “theory of mind” – the ability to infer that each person is their own “I”, with independent experiences and private mental states. In The Book of Minds, the science writer Philip Ball describes the classic experiment that tests the development of this ability in children. A child and an adult watch as an object is hidden under one of three cups. Then the adult leaves the room and the child sees a second adult come in and move the object so it’s under a different cup.

When the first adult returns, where does the child expect she will look for the object? Very young children assume that she will know its new location, just as they do. Starting around age four, however, children start to understand that the adult only knows what she has seen herself, so they expect her to look under the original, now empty cup. “Indeed,” Ball writes, “they will often delight in the deception: in their knowing what others don’t.”

Developing a theory of mind is necessary because we can never know what is going on inside other people in the same immediate way we know ourselves. Most adults take for granted that other people have the same kind of inner life they do, but this remains a kind of assumption. René Descartes was one of the first philosophers to wrestle with this problem, in the 17th century. “What do I see from the window but hats and coats which may cover automatic machines?” he asked. “Yet I judge these to be men.” But Descartes didn’t extend the same benefit of the doubt to animals. Even more than Skinner, he saw them as automata without any inner experience, “bêtes-machines”. Ball notes that Descartes dissected live animals to study the circulation of the blood, “and dismissed any cries of pain that procedure elicited as a mere mechanical response, not unlike the screech of a poorly oiled axle”.

Four centuries later, De Waal complains that science still hasn’t overcome the tendency to draw a dividing line between the inner lives of humans and those of other creatures. The reason that scientists have focused on theory of mind, De Waal believes, is because no animal has been shown to possess it. Such “interspecific bragging contests”, he writes, are designed to flatter our sense of superiority. In fact, it seems that even here we’re not clear winners. According to Ball, recent attempts to replicate the theory-of-mind experiment with chimps and bonobos suggest that the majority of them pass the test, though the evidence is ambiguous: since the subjects can’t talk, researchers gauge their expectations by tracking their eye movements.

 Even if other species were conclusively found to possess a theory of mind, of course, it would not challenge our monopoly on the kind of “rational soul” that produced the pyramids and monotheism, the theory of evolution and the intercontinental ballistic missile. As long as these quintessentially human accomplishments remain our standard for intellectual capacity, our place at the top of the mental ladder is assured.

But are we right to think of intelligence as a ladder in the first place? Maybe we should think, instead, in terms of what Ball calls “the space of possible minds” – the countless potential ways of understanding the world, some of which we may not even be able to imagine. In mapping this space, which could theoretically include computer and extraterrestrial minds as well as animal ones, “we are currently no better placed than the pre-Copernican astronomers who installed the Earth at the centre of the cosmos and arranged everything else in relation to it”, Ball observes. Until we know more about what kinds of minds are possible, it is sheer hubris to set up our own as the standard of excellence.

Xenophanes, a pre-Socratic philosopher, observed that if horses and oxen could draw pictures, they would make the gods look like horses and oxen. Similarly, if non-human beings could devise a test of intelligence, they might rank species according to, say, their ability to find their way home from a distance unaided. Bees do this by detecting magnetic fields, and dogs by following odours, while most modern humans would be helpless without a map or a GPS. “Earth is bursting with animal species that have hit on solutions for how to live a good life in ways that put the human species to shame,” Gregg says.

But if human and animal minds are so essentially different that we can never truly understand one another, then a troubling thought arises: we would be less like neighbours than inmates who occupy separate cells in the same prison. The kind of understanding Foster achieved with his octopus, or Goodall with her chimpanzees, would have to be written off as an anthropomorphising illusion, just as Skinner warned.

The possibility of true interspecies understanding is the subject of Thomas Nagel’s landmark 1974 essay What Is It Like to Be a Bat?, to which every writer on animal cognition pays their respects, sometimes wearily. Nagel, an American philosopher, concluded that humans can never really understand a bat’s inner experience. Even if I try to picture what it’s like to fly on webbed wings and spend most of my time hanging upside down, all I can imagine is what it would be like for me to be a bat, not what it’s like for a bat to be a bat.

For Nagel, this conclusion has implications beyond animal psychology. It proves that mental life can never be reduced to things we can observe from the outside, whether that means the way we behave or the pattern of electrical impulses in our neurons. Subjectivity, what it feels like to exist, is so profoundly different from what we can observe scientifically that the two realms can’t even be described in the same language.

Few people have ever taken the challenge of Nagel’s essay as literally as Charles Foster in his 2016 book Being a Beast. A barrister and academic by profession, Foster set himself the challenge of entering the mental worlds of five animal species by living as much like them as possible. To be a fox, he writes: “I lay in a back yard in Bow, foodless and drinkless, urinating and defecating where I was, waiting for the night and treating as hostile the humans in the row houses all around.” To be a badger, he dug a trench in the side of a hill and lived inside it with his young son Tom, eating earthworms and inhaling dust. “Tom was filling tissues with silica and blood for a week,” Foster notes.

Foster welcomes all this damage and discomfort, but not in the spirit of a scientist doing fieldwork. Rather, he evokes the medieval flagellants who covered their backs with welts to purge themselves of sin. That Foster defines sin as a transgression against nature rather than God doesn’t make the concept any less religious. “Evolutionary biology is a numinous statement of the interconnectedness of things,” he writes, and his preaching translates easily into Christian terms: “Say, with Saint Francis, ‘Hello, Brother Ox,’ and mean it,” he demands.

Foster’s way of seeking communion with the animals may be extreme, at times comically so, but his basic impulse is shared by many of today’s students of animal cognition, and an increasing number of laypeople as well. Encountering an animal mind can perform the same function as a great work of art or a religious experience: it makes the familiar strange, reminding us that reality encompasses far more than we ordinarily think.

The great difference is that while a traditional religious experience can awaken human beings to God, an animal epiphany can awakens us to the fullness of this world. “What she taught me was to feel that you’re part of this place, not a visitor,” Foster says in the closing lines of My Octopus Teacher, and by “this place” he doesn’t just mean a particular kelp forest, but the Earth itself. At first this might sound like an odd realisation: where else would human beings belong if not on our one and only planet?

But in the 21st century, it is clearly becoming harder for us to think of ourselves as genuinely belonging to the Earth. Whether we look back on our long history of driving other species to extinction, or forward to a future in which we extinguish ourselves through climate breakdown, many humans now see humanity as the greatest danger facing the Earth – a cancer that grows without limit, killing its host.

It is no coincidence that, at the same moment, tech visionaries have begun to think about our future in extraterrestrial terms. Earth may be where humanity happened to evolve, they say, but our destiny calls us to other worlds. Elon Musk founded SpaceX in 2002 with the explicit goal of hastening humanity’s colonisation of Mars. Other “transhumanist” thinkers look forward to a fully virtual future, in which our minds leave our bodies behind and achieve immortality in the form of electromagnetic pulses.

These projects sound futuristic, but they are best understood as new expressions of a very old human anxiety. We have always suffered from metaphysical claustrophobia – the sense that a cosmos containing no minds but our own was intolerably narrow. That is why, since prehistoric times, humans have populated Earth with other kinds of intelligences – from gods and angels to fairies, forest-spirits and demons. All premodern cultures took the existence of such non-human minds for granted. In medieval Europe, Christian and Greek philosophical ideas gave rise to the doctrine of the “great chain of being”, which held that the universe is populated by an unbroken series of creatures, all the way from plants at the bottom to God at the apex. Humanity stood in the middle, more intelligent than the animals but less than the angels, who came in many species, with different powers and purviews.

 Filling the universe with hypothetical minds, superior to our own in wisdom and goodness, helps relieve our species’ loneliness, giving us beings we could talk to, think about, and strive to emulate. Our need for that kind of company in the universe hasn’t gone away, though today we prefer to fill the region “above” us in the space of possible minds with advanced extraterrestrials and superpowered AIs – beings that are just as hypothetical as seraphim and cherubim, at least so far.

Our rising interest in animal minds can be seen as a way of filling in the regions “below” us as well. If an octopus is like an intelligent alien, as Godfrey-Smith writes, then we don’t need to scan the skies so anxiously for an actual extraterrestrial. Yong quotes Elizabeth Jakob, an American spider expert, to the same effect: “We don’t have to look to aliens from other planets … We have animals that have a completely different interpretation of what the world is right next to us.” Perhaps simply knowing that these other minds exist can help us make peace with the limitations of our own.

 

Can humans ever understand how animals think? By Adam Kirsch. The Guardian, May 30, 2023.

Naturalist Charles Foster wanted to reconnect with his inner beast – so he tried living as a badger, a deer and a fox

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Charles Foster lifts a wriggling worm to his lips. “Cheers,” he says.
 
We clink worms.
 
He warns that it might try to escape, and that there will be a strange, stereo-squirmy sensation when the worm splits in two.
 
He grimaces and chews pedantically to make sure every last bit has gone. Foster’s right: there is a grittiness to them. Earthworms wouldn’t be my first choice on the à la carte.
 
Foster has been on all fours for much of the morning, reminiscing about the periods he spent living as a badger, an otter, an urban fox. He also spent time, less successfully, as a red deer and a swift. In one way or another, he says, he has spent most of his 53 years being an animal, or at least trying to.
 
As a toddler in Manchester, he would look out of his bedroom window, fascinated by the tawny owl perched on a lamp outside. The family moved to Sheffield, where it was the blackbird in the garden he couldn’t stop thinking about. The bird stared at him with its yellow eye-rings and black pupils, taunting him. It knew something, and Foster wanted to know what.
 
“I was tantalised and infuriated,” he says. “I went down to the local library and read everything I could about blackbirds. I got a blackbird brain and pickled it in formalin, and would sleep holding it, wondering whether its wisdom would diffuse into me. I stuffed a blackbird and it circled on a piece of thread above my head when I went to sleep at night. I mapped every blackbird nest in our area and put them down in charts. I made maps of their flight path, and took ladders and looked into their nests. And I failed utterly to work out what made a blackbird tick.”
 
Foster was an unusual boy who grew into an unusual man. He was born to high-achieving, working-class parents who both became head teachers of primary schools. He had even greater ambitions for himself. His parents sent him to the local comprehensive, but he went to the library and read up about public school scholarships. Without telling his parents, he applied for one and won it. He left the comp to go to public schools far away in Bristol and Shrewsbury, where he entered a new world of privilege and expectation. Part of him hated it, but he thrived.

 
He promised himself he would re-engage with the natural world after his O-levels. “As soon as the last paper was finished, I went home and spent a day and a night lying in the Mayfield Valley just above our home in Sheffield, at a hare’s eye level. This was a sort of redemptive process that would undo all the life-denying process of the exams. That was my first conscious attempt to live like an animal.”
 
Did he enjoy it? “Enjoy isn’t the word. But I could feel a lot of toxins were being washed out. That seeded in me something – that in living the life we normally live, we are living a life that isn’t natural. And in order to be properly human, we’ve got to be properly animal.” Foster pauses and looks at me. “Do you think I’m insane?”
 
Convention got the better of him again. Foster sacrificed his inner hare and went to Cambridge University, where he studied veterinary science and law. After he left, he worked as a vet and a barrister, as an academic teaching medical law and ethics, as a philosopher and as a magazine columnist. (He still dabbles in all of these, and currently teaches at Oxford University.) He couldn’t have moved further away from the little boy who worshipped the spontaneity of nature. Instead of empathising with wild animals, Foster started shooting them for pleasure. He ran ultramarathons, 150 miles in a week, over the deserts of Africa. He made good money as a barrister, hunted in tweeds and lived the good life.
 
He soon felt a fraud. “The secret of a good barrister is that they are an empty vessel into which the soul of the latest murderer or rapist can be poured. It’s a very spiritually debilitating job to do. The damage that did called me to consider: what on earth is this creature called Charles Foster who occasionally voices opinions, who says he is a moral agent, who says he has ethical positions?”
 
Who did he think the real Charles Foster was? “The real Charles Foster grew up in a little semi in Sheffield and had his mates up and down the road, whereas I had remade myself as something else.” He saw himself as the kind of swashbuckling hero that Rider Haggard might have created. “I was a very arrogant, presumptuous, fantastically self-confident barrister. Even by barristers’ standards.”
 
One day he had an epiphany – well, an anti-epiphany. He was on an expedition across the Sinai, sitting in the midday sun, and he started to weigh up his achievements. “I thought: I will spend my time looking at the enormously fascinating, kaleidoscopically colourful soul of the fantastic Charles Foster. And I couldn’t see anything at all. It was like looking into a well. There was a rising sense of panic, from which it took years to recover.”
 
How did the fallout express itself? “A lot of the pinstriped swaggering vanished overnight,” he says. “The pride haemorrhaged away. I was a pretty broken person. I mean, I continued at the bar, I carried on working. But I became increasingly introspective.”

 
In his mid-30s, Foster’s first marriage fell apart and he started spending more time trying to understand what made animals tick: what is it like to be an otter guided by the smell of shit? Was he as competent a city dweller as an urban fox?
 
We stop at a spot in the woods. See, this could make a nice little sett, he says. He points to a small hollow covered with branches. Foster is a big man – 6ft 3in and a good 15 stone – but he eases himself into the hollow with surprising dexterity. When he lived as a badger in Wales with his son, Tom, they would sleep by day and prowl by night. In Being A Beast, the book he has written about his experiences, Foster wonderfully conveys the sensuality of life where smell is everything, and sight virtually irrelevant. But the book is very funny about his many bestial failings. Yes, he and Tom can cope in the summer, when badger life is a form of extreme camping, but returning in midwinter is a different matter. As an otter, he had less success. Part of the problem was he didn’t like otters: nasty killers with little to recommend them. He enjoyed the sprainting (shit-sniffing, which he did with his children; before long, they could distinguish each other’s poo) and spent hours swimming the lakes on Exmoor. But no, otter life didn’t do much to enrich the soul.
 
As for being a red deer, he really struggled. Yes, he grew his toenails and hair long, but these felt like superficial gestures. He asked a friend to set his bloodhound on him, so he could know what it was like to be hunted. There was an initial surge of adrenaline as he ran, but ultimately the experience was humiliating: when the dog tracked him down, it just gave him a contemptuous glance and walked off. Foster admits he was a rubbish deer. “I found it impossible to come down the pyramid and become a victim.”
 
By contrast, there is something ecstatic in his hopeless attempts to be a swift. He adores these most ethereal of birds, and is in awe of their ability to find their way from the eaves of his study in Oxford to their ancestral home in Congo and back again, to fly 30,000 miles a year without perching (swifts sleep and mate in the air). Foster goes paragliding, follows their path to Africa, eats similar foods; but it serves only to remind him how lumpen he is.
 
It is freezing but gloriously sunny in the woods. Foster slips out of his sett, takes off the mask the Guardian has lent him for the photoshoot, lights his tiny Hexamine cooker and knocks up a few barbecued worms, which he serves with nettles and garlic. They taste better cooked: less slippery.
 
You know, I say, I think you were most at home as a badger. “Why do you say that?” he asks. He looks disappointed. “I think I got closer to foxes than anyone else.”
 
I feel bad. Of course he made a much better fox: he got to scavenge through rubbish bins, mooch around London, share their emotional intelligence. “I wasn’t able to be olfactory enough as a badger,” Foster explains. “Another reason I didn’t get so close to badgers is that they are much more naturally relational animals than I am. I’m actually quite a lonely, wretched animal – and badgers aren’t.”
 
Tom made a great badger, I say. He puffs up with pride. “Yes, Tom’s a fantastic badger.”
 
We head off home where Mary, Foster’s second wife, has made pumpkin soup for lunch. She is a lovely, grounded woman who runs the house and looks after their four young children (Foster has two more from his first marriage); Mary also works as a GP one day a week. You can’t move in the house without bumping into stuffed birds, badgers, foxes and otters. A zebra skin dominates one wall in the lounge. I thought Foster despised his shooting days? “But it’s so beautiful.” Isn’t there something masochistic in having it there? “Yes,” he says, “it’s a bit like Christian ascetics constantly reminding themselves of the sins of the past.”
 
We sit down to lunch. I ask Mary if it took him long to adapt whenever he came back to domestic life. “He re-engaged with the family quite quickly,” she says. “The hardest thing for him was probably using knives and forks. Sitting at a table. Basic social mores. He likes standing up to eat anyway, walking around and doing things.”
 
Could she tell the difference when he returned after being a badger from, say, when he returned from being an otter? “I don’t think I could, no,” Mary answers gently. “I’m usually preoccupied with children’s bottoms and putting food on the table.” She looks at Foster affectionately. “You don’t get the attention you deserve!”
 
Was Mary surprised when he announced he’d be living as a beast? “Oh, no,” she says. “None of it was alien to what he’s ever been. I mean, you were living as an urban fox in London before I met you. Skulking around in the park at night.”
 
“I wasn’t sleeping in parks back then,” Foster clarifies. “I was trying to get into the head of an urban fox, eating out of dustbins and sometimes sleeping under bushes. I was doing that on and off most of the time I lived in London.”

 
Mary smiles. “I domesticated you, didn’t I?”
 
She says he has always been an extremist. “You suck the marrow out of it and agonise over it, to feel you’ve got to grips with it.” What form does his agonising take? “Verbal and physical. Always obsessing over the meaning of life, and what it means to be fully human. Whereas I just think, well, we’ve got to feed the kids.”
 
In the end, Foster’s book is a beautiful and bonkers metaphysical quest, with a number of questions at the heart of it – some universal (what does it meant to be human?), but most tied up with his own identity (what does it mean to be Charles Foster?). “All of us, I guess, wonder how real our relationships are,” he explains. “We wonder whether we are talking at cross-purposes, whether we can know anything about our nearest and dearest – this was just another lens through which to view that question. I thought, if I can have a relationship with something that is as different from me as a fox or a badger, then there’s a possibility that I might be able to know my wife or my children or my best friend.”
 
The revelation occurred when he was living as a fox, and came face to face with another fox that had stolen his chicken leg. “I felt not just that I was looking and observing, but that I was being looked at and being observed. That was the reciprocity I had longed for. I don’t feel I got that anywhere else.” And he came off second best to the real fox? “Oh yes! It was a better Londoner, a better liver. It could run faster, it needed less sleep, its teeth were sharper, it nose and ears were better. It was just superior.”
 
It made the whole exercise worthwhile, he says. “I’m reassured that relationships aren’t impossible. I’m reassured that I know something about Mary. I’m reassured that there is some core identity called Charles Foster, who’s capable of making real choices.” The angst-ridden uberman relaxes into a smile. “It’s made me slightly less insecure.”
 
Going Underground : meet the man who lived like an animal.  By Simon Hattenstone. The Guardian, January  23, 2016

The Anthropocene Epoch

It was February 2000 and the Nobel laureate Paul Crutzen was sitting in a meeting room in Cuernavaca, Mexico, stewing quietly. Five years earlier, Crutzen and two colleagues had been awarded the Nobel prize in chemistry for proving that the ozone layer, which shields the planet from ultraviolet light, was thinning at the poles because of rising concentrations of industrial gas. Now he was attending a meeting of scientists who studied the planet’s oceans, land surfaces and atmosphere. As the scientists presented their findings, most of which described dramatic planetary changes, Crutzen shifted in his seat. “You could see he was getting agitated. He wasn’t happy,” Will Steffen, a chemist who organised the meeting, told me recently.

What finally tipped Crutzen over the edge was a presentation by a group of scientists that focused on the Holocene, the geological epoch that began around 11,700 years ago and continues to the present day. After Crutzen heard the word Holocene for the umpteenth time, he lost it. “He stopped everybody and said: ‘Stop saying the Holocene! We’re not in the Holocene any more,’” Steffen recalled. But then Crutzen stalled. The outburst had not been premeditated, but now all eyes were on him. So he blurted out a name for a new epoch. A combination of anthropos, the Greek for “human”, and “-cene”, the suffix used in names of geological epochs, “Anthropocene” at least sounded academic. Steffen made a note.

A few months after the meeting, Crutzen and an American biologist, Eugene Stoermer, expanded on the idea in an article on the “Anthropocene”. We were entering an entirely new phase of planetary history, they argued, in which human beings had become the driving force. And without a major catastrophe, such as an asteroid impact or nuclear war, humankind would remain a major geological force for many millennia. The article appeared on page 17 of the International Geosphere-Biosphere Programme’s newsletter.

At this point it did not seem likely the term would ever travel beyond the abstruse literature produced by institutions preoccupied with things like the nitrogen cycle. But the concept took flight. Environmental scientists latched on to what they saw as a useful catch-all term for the changes to the natural world – retreating sea ice, accelerating species extinction, bleached coral reefs – that they were already attributing to human activity. Academic articles began to appear with “Anthropocene” in the title, followed by entire journals dedicated to the topic. Soon the idea jumped to the humanities, then newspapers and magazines, and then to the arts, becoming a subject of photography, poetry, opera and a song by Nick Cave. “The proliferation of this concept can mainly be traced back to the fact that, under the guise of scientific neutrality, it conveys a message of almost unparalleled moral-political urgency,” wrote the German philosopher Peter Sloterdijk.

There was just one place where the Anthropocene seemed not to be catching on: among the geologists who actually define these terms. Geologists are the guardians of the Earth’s timeline. By studying the Earth’s crust, they have carved up the planet’s 4.6bn years of history into phases and placed them in chronological order on a timescale called the International Chronostratigraphic Chart. That timescale is the backbone of geology. Modifying it is a slow and tortuous process, overseen by an official body, the International Commission on Stratigraphy (ICS). You can’t just make up a new epoch and give it a convincing name; the care taken over the timescale’s construction is precisely what gives it authority.

 To many geologists, accustomed to working with rocks that are hundreds of millions of years old, the notion that a species that has been around for the blink of an eye was now a genuine geological force seemed absurd. Few would deny we are in a period of climatic turmoil, but many feel that, compared with some of the truly apocalyptic events of the deep past – such as the period, 252m years ago, when temperatures rose 10C and 96% of marine species died – the change so far has not been especially severe. “Many geologists would say: it’s just a blip,” Philip Gibbard, the secretary-general of the ICS, told me.

But as the idea of the Anthropocene spread, it became harder for geologists to ignore. At a meeting of the Geological Society of London, in 2006, a stratigrapher named Jan Zalasiewicz argued that it was time to look at the concept seriously. Stratigraphy is the branch of geology that studies rock layers, or strata, and it is stratigraphers who work on the timescale directly.

To Zalasiewicz’s surprise, his colleagues agreed. In 2008, Gibbard asked if Zalasiewicz would be prepared to assemble and lead a team of experts to investigate the matter more deeply. If the group found evidence that the Anthropocene was “stratigraphically real”, they would need to submit a proposal to the ICS. If the proposal was approved, the result would be literally epoch-changing. A new chapter of Earth’s history would need to be written.

With a mounting sense of apprehension, Zalasiewicz agreed to take on the task. He knew the undertaking would not only be difficult but divisive, risking the ire of colleagues who felt that all the chatter around the Anthropocene had more to do with politics and media hype than actual science. “All the things the Anthropocene implies that are beyond geology, particularly the social-political stuff, is new terrain for many geologists,” Zalasiewicz told me. “To have this word used by climate commissions and environmental organisations is unfamiliar and may feel dangerous.”

What’s more, he had no funding, which meant he would have to find dozens of experts for the working group who would be willing to help him for free. Having spent much of his career absorbed in the classification of 400m-year-old fossils called graptolites, Zalasiewicz did not consider himself a natural people manager. “I found myself landed in this position,” he said. “My reaction was: goodness me, where do we go from here?”

 Working out the age of the planet has always been a fraught business. The Bible stated that God created everything in six days, but it wasn’t until the 17th century that scholars made a concerted effort to work out precisely when that week might have been. For some time, the estimate of one scholar, an Irish archbishop named James Ussher, held sway: the world began on 23 October 4004 BC.

Then, in the late 18th century, a different theory emerged, one based on the close observation of the natural world. By studying the near-imperceptibly slow process of the weathering and forming of rocks, thinkers such as the Scottish landowner James Hutton argued that the Earth must be far, far older than previously thought.

The invention of geology would go on to transform our sense of our place in existence, a revolution in self-perception similar to the discovery that the Earth is not at the centre of the universe. Human beings were suddenly an astonishingly recent phenomenon, a “parenthesis of infinitesimal brevity”, as James Joyce once wrote. During the almost inconceivable expanse of pre-human time, successive worlds had risen and collapsed. Each world had its own peculiar history, which was written in rock and waiting to be discovered

In the early 19th century, geologists began naming and organising different rock formations in a bid to impose some order on the endless discoveries they were making. They used clues within the rock layers, such as fossils, minerals, texture and colour, to tell when formations in different locations dated to the same time period. For instance, if two bands of limestone contained the same type of fossilised mollusc, alongside a certain quartz, it was likely they had been laid down at the same point in time, even if they were discovered miles apart.

Geologists called the spans of time that the rock formations represented “units”. On the timescale today, units vary in size, from eons, which last for billions of years, to ages, which last for mere thousands. Units nestle inside each other, like Russian dolls. Officially, we live in the Meghalayan age (which began 4,200 years ago) of the Holocene epoch. The Holocene falls in the Quaternary period (2.6m years ago) of the Cenozoic era (66m) in the Phanerozoic eon (541m). Certain units attract more fanfare than others. Most people recognise the Jurassic.

 As geologists began dividing deep time into units, they came up against the difficult question of boundaries – defining precisely where one phase of history transitions into the next. In the late 19th century, it was recognised that if the field was to advance, global cooperation and coordination would be necessary. The International Commission on Nomenclature, the forerunner of the present-day ICS, was established during a congress in Bologna in 1881 with the mandate of creating an international language of geology, one that was to be enshrined in the timescale.

The task of interpreting and classifying 4.6bn years of Earth history continues today. Geologists have barely begun to describe the Precambrian eon, which spans Earth’s first 4bn years. Meanwhile, well-studied units are revised as new evidence unsettles old assumptions. In 2004, the Quaternary period was unceremoniously jettisoned and the preceding period, the Neogene, extended to cover its 1.8m years. The move came as a surprise to many Quaternary geologists, who mounted an aggressive campaign to redeem their period. Eventually, in 2009, the ICS brought the Quaternary back and moved its boundary down by 800,000 years to the beginning of an ice age, a point considered more geologically significant. Having now “lost” millions of years, Neogene scientists were incandescent. “You might ask: who wasn’t upset by it?” Gibbard told me.

Modifying the geological timescale is a bit like trying to pass a constitutional amendment, with rounds of proposal and scrutiny overseen by the ICS. “We have to be relatively conservative,” said Gibbard, “because anything we do is going to have a longer-term implication in terms of the science and literature.” First, a working group drafts a proposal which is submitted to an expert subcommission for review and vote. From the subcommission, the proposal advances to the voting members of the ICS (composed of the chairs of the subcommissions, plus the chair, vice-chair and general-secretary of the ICS). Once the ICS has voted in its favour, it passes to the International Union of Geological Sciences (IUGS), geology’s highest body, to be ratified.

Whether or not a new proposal successfully passes through all these rounds comes down to the quality of evidence that the working group can amass, as well as the individual predilections of the 50-or-so seasoned geologists who constitute the senior committees.

This did not bode well for Zalasiewicz as he began to put together the Anthropocene working group. In fundamental ways, the idea of the Anthropocene is unlike anything geologists have considered before. The planet’s timekeepers have built their timescale from the physical records laid down in rocks long ago. Without due time to form, the “rocks” of the Anthropocene were little more than “two centimetres of unconsolidated organic matter”, as one geologist put it to me. “If we think about the Anthropocene in purely geological terms – and that’s the trouble, because we’re looking at it with that perspective – it’s an instant,” said Gibbard.

Zalasiewicz grew up in the foothills of the Pennines in a house that contained his parents, sister and a growing collection of rocks. When he was 12, his sister brought home a nestful of starlings, which his mother, who loved animals, nursed to health. Soon neighbours started calling round with all manner of injured birds, and for several years Zalasiewicz shared his bedroom with a little owl and a kestrel. (Kestrels, he came to know, are “rather thick creatures”.) He started volunteering at the local museum in Ludlow in the summer, where he met people who were expert in the things he cared most about, such as where to find trilobites. By his mid-teens, he told me, “geology was it”.

Now 64, Zalasiewicz is small and slight, with silver hair that sticks out like a scarecrow’s. He has worked in Leicester University’s geology department for 20 years, and presents himself as a quintessential geologist, a wearer of leather elbow patches and lover of graptolites. Yet among geologists, he is a known provocateur. His reputation stems from one of his papers, published in 2004, in which he argued that stratigraphy should throw out some of the terminology that has been in use since the discipline’s earliest days in favour of more modern terms. It was, to some, an audacious suggestion. When I emailed David Fastovsky, the former editor of the journal Geology, who had published the paper 15 years ago, he remembered it well. “The general feeling at the time,” he wrote, “was that it might be possible, but who would dare to take the first shot?”

Over the years, Zalasiewicz has indulged in thought experiments that are, among geologists, peculiar. In 1998, he wrote an article for New Scientist in which he imagined what mark humans might leave on the Earth long after we are extinct. His ideas became a book, published 10 years later, called The Earth After Us. Geologists tend to have their minds trained on the deep past, and Zalasiewicz’s forward-thinking approach marked him out. When, in 2006, Zalasiewicz broached the subject of the Anthropocene at the Geological Society meeting, Gibbard recalled thinking: “Well, these two go together very well.”

After he was appointed chair of the Anthropocene working group, Zalasiewicz needed to assemble his team. “At the time, it was simply a hypothetical and interesting question: can this thing be for real geologically?” Zalasiewicz told me when I visited him in Leicester last year. “It was arm-waving with very little specific detail. The diagrams were back-of-the-beer-mat things.”

Stratigraphic working groups are, not surprisingly, usually composed of stratigraphers. But Zalasiewicz took a different approach. Alongside traditional geologists, he brought in Earth systems scientists, who study planet-wide processes such as the carbon cycle, as well as an archeologist and an environmental historian. Soon the group numbered 35. It was international in character, if overwhelmingly male and white, and included experts with specialisms in paleoecology, radiocarbon isotopes and the law of the sea.

If the Anthropocene was, in fact, already upon us, the group would need to prove that the Holocene – an unusually stable epoch in which temperature, sea level and carbon dioxide levels have stayed relatively constant for nearly 12 millenia – had come to an end. They began by looking at the atmosphere. During the Holocene, the amount of CO2 in the air, measured in parts per million (ppm), was between 260 and 280. Data from 2005, the most recent year recorded when the working group started out, showed levels had climbed to 379 ppm. Since then, it has risen to 405 ppm. The group calculated that the last time there was this much CO2 in the air was during the Pliocene epoch 3m years ago. (Because the burning of fossil fuels in pursuit of the accumulation of capital in the west has been the predominant source of these emissions, some suggest “Capitalocene” is the more appropriate name.)

Next they looked at what had happened to animals and plants. Past shifts in geological time have often been accompanied by mass extinctions, as species struggle to adapt to new environments. In 2011, research by Anthony Barnosky, a member of the group, suggested something similar was underway once again. Others investigated the ways humans have scrambled the biosphere, removing species from their natural habitat and releasing them into new ones. As humans have multiplied, we have also made the natural world more homogenous. The world’s most common vertebrate, the broiler chicken, of which there are 23bn alive at any one time, was created by humans to be eaten by humans.

Then there was also the matter of all our stuff. Not only have humans modified the Earth’s surface by building mines, roads, towns and cities, we have created increasingly sophisticated materials and tools, from smartphones to ballpoint pens, fragments of which will become buried in sediment, forming part of the rocks of the future. One estimate puts the weight of everything humans have ever built and manufactured at 30tn tonnes. The working group argued that the remnants of our stuff, which they called “technofossils”, will survive in the rock record for millions of years, distinguishing our time from what came before.

By 2016, most of the group was persuaded that what they were seeing amounted to more than a simple fluctuation. “All these changes are either complete novelties or they are just off the scale when it comes to anything Holocene,” Zalasiewicz told me. That year, 24 working group members co-authored an article, published in the journal Science, announcing that the Anthropocene was “functionally and stratigraphically distinct” from the Holocene.

But the details were far from settled. The group needed to agree a start-date for the Anthropocene, yet there was nothing as clean as a colossal volcanic eruption or an asteroid strike to mark the point where it began. “From a geological point of view, that makes life very difficult,” said Gibbard, who is also a member of the working group.

The group was split into opposed camps, largely according to their academic specialisation. Initially, when he first proposed the notion of the Anthropocene, Paul Crutzen, who is an atmospheric chemist, had suggested the industrial revolution as the start-date because that was when concentrations of CO2 and methane began accumulating significantly in the air. Lately the Earth system scientists had come to prefer the start of the so-called “great acceleration”, the years following the second world war when the collective actions of humans suddenly began to put much more strain on the natural world than ever before. Most stratigraphers were now siding with them – they believe that the activity of the 1950s will leave a sharper indentation on the geological record. This concerned the archaeologists, who felt that privileging a 1950 start-date dismissed the thousands of years of human impact that they study, from our early use of fire to the emergence of agriculture. “There is a feeling among the archaeologists that because the word ‘anthropo’ is in there, their science should be central,” one geologist complained to me privately. Agreeing the start-date, Gibbard warned, could be the Anthropocene’s “stumbling block”.

At the tail end of last summer, members of the working group boarded flights to Frankfurt and then took a 45-minute train west, to Mainz. Over two days, they gathered at the Max Planck Institute for Chemistry for the group’s annual meeting. Crutzen, now in his mid-80s, spent much of his career at the institute, and he was present both as a spectator and in the form of a bronze bust in the foyer. I asked him what he made of the progress of his idea. “It started with a few people and then it exploded,” he said.

Under the glow of a projector in a darkened classroom, two dozen researchers shared their latest findings on topics such as organic isotope geochemistry and peat deposits. Things proceeded without a wrinkle until the second day, when a debate broke out about the start date, which then turned into a debate about whether it was OK for different intellectual communities to use the term “Anthropocene” to mean different things. Someone at the back suggested adding the word “epoch” for the strictly geological definition, so “Anthropocene” by itself could be used generally.

“It’s just a personal view, but I think it would be confusing to have the same term having different meanings,” said a stratigrapher.

“I don’t think it would be that confusing,” an environmental scientist countered.

In the front row, Zalasiewicz watched with the air of an adjudicator. Eventually, he chimed in. “Certainly, in terms of our remit, we can only work from the geological term. We can’t police the word ‘Anthropocene’ beyond that,” he said. Throughout the meeting, Zalasiewicz seemed at pains to emphasise the Anthropocene’s geological legitimacy. He was aware that a number of influential geologists had taken against the idea, and he was worried about what might happen if the working group was seen to be straying too far from the discipline’s norms.

One of the loudest critics of the Anthropocene is Stanley Finney, who as the secretary-general of the IUGS, the body that ratifies changes to the timescale, is perhaps the most powerful stratigrapher in the world. During the meeting in Mainz, I was told that Finney was both a “big phallus of the discipline” and “really vehemently anti-Anthropocene”.

Zalasiewicz told me that Finney was an accomplished geologist, but one of a different temperament. “He sees me as someone who tries to bring in these crazy ideas by the backdoor,” he said. “I guess if you’re a geologist who spends your time in the past where you have these enormous vistas of time – the human-free zone, if you like – then to have something as fast, busy, crowded, as science-fiction-like, come into the steady, formalised, bureaucratised array of geological time, I can see it as something you might naturally take against.”

When Finney first came across the term “Anthropocene”, in a paper written by Zalasiewicz in 2008, he thought little of it. To him, it just seemed like a big fuss over the human junk on the surface of the planet. Finney, who is 71 and a professor of geological sciences at California State University, Long Beach, has spent much of his career trying to picture what the planet was like 450m years ago, during the Ordovician period, when the continents were bunched together in the southern hemisphere and plants first colonised land. Over the years, he has worked his way up through stratigraphy’s hierarchy. By the time Zalasiewicz was appointed chair of the working group, Finney was chair of the ICS. The two scientists knew each other professionally. Zalasiewicz’s favourite fossils, graptolites, are found in Ordovician strata.

But for some time the pair had not seen eye to eye. When Zalasiewicz published his 2004 paper arguing that stratigraphers should cast off their long-established terminology, Finney was affronted by this lack of respect for the discipline’s traditions. In an attempt to find a middle ground, the pair worked on a “compromise paper”. As the writing got underway, things turned sour. Finney began to feel that Zalasiewicz was not treating his suggested revisions seriously. “He would take my comments and he would make tiny little changes but still keep the whole thing,” Finney told me. “When I saw the final draft that was ready to be accepted [by a journal], I said: ‘Take my name off, I’m not happy with this. Just take my name off.’” From then on, their relations assumed a cool distance.

Finney only decided to look at the Anthropocene in detail after he began getting comments from people who thought it was now an official part of the geological timescale. The more he looked, the less he liked the idea. “You can make the ‘big global changes’ issue out of it if you want, but as geologists we work with rocks, you know?” he told me. To Finney, a negligible amount of “stratigraphic content” has amassed since the 1950s. Geologists are used to working with strata several inches deep, and Finney thought it was excessively speculative to presume that humans’ impact will one day be legible in rock. As the Anthropocene working group gained momentum, he grew concerned that the ICS was being pressured into issuing a statement that at its heart had little to do with advancing stratigraphy, and more to do with politics.

  

Academics both inside and outside geology have noted the Anthropocene’s political implications. In After Nature, the law professor Jedediah Purdy writes that using the term “Anthropocene” to describe a wide array of human-caused geological and ecological change is “an effort to meld them into a single situation, gathered under a single name”. To Purdy, the Anthropocene is an attempt to do what the concept of “the environment” did in the 1960s and 70s. It is pragmatic, a way to name the problem – and thus begin the process of solving it.

Yet if a term becomes too broad, its meaning can become unhelpfully vague. “There is an impulse to want to put things in capital letters, in formal definitions, just to make them look like they’re nicely organised so you can put them on a shelf and they’ll behave,” said Bill Ruddiman, professor emeritus at the University of Virginia. A seasoned geologist, Ruddiman has written papers arguing against the stratigraphic definition of the Anthropocene on the grounds that any single start-date would be meaningless since humans have been gradually shaping the planet for at least 50,000 years. “What the working group is trying to say is everything pre-1950 is pre-Anthropocene, and that’s just absurd,” he told me.

Ruddiman’s arguments have found wide support, even from a handful of members of the working group. Gibbard told me he had started out “agnostic” about the Anthropocene but lately he had decided it was too soon to tell whether or not it really was a new epoch. “As geologists, we’re used to looking backwards,” he said. “Things that we’re living through at the moment – we don’t know how significant they are. [The Anthropocene] appears significant but it would be far easier if we were 200 to 300, possibly 2,000 to 3,000, years in the future and then we could look back and say: yes, that was the right thing to do.”

Yet for the majority of the working group, the stratigraphic evidence for the Anthropocene is compelling. “We realise the Anthropocene goes against the grain of geology in one sense, and other kinds of science, archaeology and anthropology, in another sense,” Zalasiewicz told me. “We try and deal honestly with their arguments. If they were to put out something that we couldn’t jump over, then we’d hold up our hands and say: OK, that’s a killer blow for the Anthropocene. But we haven’t seen one yet.”

The day after the Mainz conference came to a close, a small number of working group members met at the central station and took a train to Frankfurt airport. As the train left the city it crossed the Rhine, a wide river the colour of tepid tea. Buildings became sparse, giving way to flat fields crossed by pylons and wires.

For all the years of discussion, research and debate, after the meeting it was obvious that the Anthropocene working group was still a long way off submitting its proposal to the ICS. Zalasiewicz’s favourite joke, that geologists “work in geological time”, was starting to wear thin. Proposals to amend the timescale require evidence in the form of cores of sediment that have been extracted from the ground. Within the core there must be a clear sign of major environmental change marked by a chemical or biological trace in the strata, which acts as the physical evidence of where one unit stops and another begins. (This marker is often called the “golden spike” after the ceremonial gold spike that was used to join two railway tracks when they met in the middle of the US in 1869, forming the transcontinental railroad.)

The core extraction and analysis process takes years and costs hundreds of thousands of pounds – money that, at that point, and despite grant applications, the group did not have. They discussed the problem on the train. “Beg, borrow and steal. That is the working group motto,” Zalasiewicz said, a little bitterly.

But in the months that followed the meeting, their fortunes changed. First, they received €800,000 in funding from an unexpected source, the Haus der Kulturen der Welt, a state-funded cultural institute in Berlin that has been holding exhibitions about the Anthropocene for several years. The money would finally allow the group to begin the core-extraction work, moving the proposal beyond theoretical discussion and into a more hands-on, evidence-gathering stage.

Then, in late April, the group decided to hold a vote that would settle, once and for all, the matter of the start-date. Working group members had one month to cast their votes; a supermajority of at least 60% would be needed for the vote to be binding. The results, announced on 21 May, were unequivocal. Twenty-nine members of the group, representing 88%, voted for the start of the Anthropocene to be in the mid-20th century. For Zalasiewicz, it was a step forward. “What we’ll do now is the technical work. We’ve now moved beyond the general, almost existential question of ‘is the Anthropocene geological?’” he said, when I called him. The important votes at the ICS were still to come, but he felt optimistic.

In Mainz, after the train pulled into the airport, the group made for the departure zone. Among the chaos of wheelie suitcases and people hurrying about, suddenly a voice cried out: “Fossils!” Zalasiewicz was off to one side, eyes fixed on the polished limestone floor. “That’s a fossil, these are fossil shells,” he said, pointing to what looked like dark scratches. One was the shape of a horseshoe, and another looked like a wishbone. Zalasiewicz identified them as rudists, a type of mollusc that had thrived during the Cretaceous, the last period of the dinosaurs. Rudists were a hardy species, the main reef-builders of their time. One rudist reef ran the length of the North American coast from Mexico to Canada.

Staring at the rudists encased in limestone slabs that had been dug out of the ground and transported many miles across land, it was strange to think of the unlikeliness of their arrival in the airport floor. The rudists beneath our feet had died out 66m years ago, in the same mass extinction event that wiped out the dinosaurs. Scientists generally believe that the impact of an asteroid in Yucatan, Mexico, plunged the planet into a new phase of climatic instability in which many species perished. Geologists can see the moment of the impact in rocks as a thin layer of iridium, a metal that occurs in very low concentrations on Earth and was likely expelled by the asteroid and dispersed across the world in a cloud of pulverised rock that blotted out the sun. To stratigraphers, the iridium forms the “golden spike” between the Cretaceous and Paleogene periods.

Now that the working group has decided roughly when the Anthropocene began, their main task is picking the golden spike of our time. They are keeping their options open, assessing candidates from microplastics and heavy metals to fly ash. Even so, a favourite has emerged. From the pragmatic stratigraphic perspective, no marker is as distinct, or more globally synchronous, than the radioactive fallout from the use of nuclear weapons that began with the US army’s Trinity test in 1945. Since the early 1950s, this memento of humankind’s darkest self-destructive impulses has settled on the Earth’s surface like icing sugar on a sponge cake. Plotted on a graph, the radioactive fallout leaps up like an explosion. Zalasiewicz has taken to calling it the “bomb spike”.

 The Anthropocene epoch: have we entered a new phase of planetary history? By Nicola Davison. The Guardian , May 30, 2019. 

Also of interest :   Have we entered the "Anthropocene"?     International  Geosphere-Biosphere Programme  October 31, 2010.