To begin, an experiment. Start by extracting a couple of thousand of your brain cells. Adult humans have about 86 billion neurons inside our skulls, so you can afford to lose a few, but don’t make a habit of it. Once you’ve acquired your sample, suspend your cells in a sterile solution filled with nutrients, growth factors and antioxidants maintained at a steady temperature of 37°C. Stir it into a slurry. Over time, the separate cells will connect up with each other. Within a few months, they’ll construct molecular scaffolding so they can self-organise into brain-like, three-dimensional structures. When they’ve done this, they generate synchronised electro-chemical waves: these follow the same patterns as fetal and neonatal brains.
Is the thing in the solution alive? Is it thinking? Is it … you, in some weird way? Ethics boards agonise over such questions, but for the biologist and neuroendocrinologist Robert Sapolsky, the experiment reveals two profound truths. The first is that it demonstrates emergence, a key concept in the natural sciences: how complex patterns and behaviours emerge from simple systems.
And the second, Sapolsky believes, is that it demonstrates the impossibility of free will. Just as there is no magical self-causing entity interfering with the cells in the solution, causing it to self-organise and generate brain waves, there is no such entity at work inside our own brains. All our actions, for good and evil, are determined by a hierarchy of physical and cultural causes.
Before Sapolsky became a bestselling author, before his career as a professor of biology, neurology and neuroscience at Stanford, before he was a primatologist studying a group of baboons on the Kenyan savannah, Sapolsky was a clinically depressed teenager growing up in an Orthodox Jewish family in Brooklyn, New York, and losing his faith. For him, there’s a profound link between his subsequent atheism, his depression and conviction that we have no control over our lives, we just experience the illusion that we do.
It feels like we choose
Philosophers have argued about the nature of freedom for thousands of years but in the early modern period, they found a new dilemma to agonise over. If the universe was governed by physical laws of cause and effect – and the discoveries of Galileo and Newton seemed to prove this was so – then the human brain must follow the same laws. We might feel as if we have agency over our actions – that we are the masters of our fate and the captains of our souls – but if our brains are just organic systems rigidly following physical laws, it’s hard to see how this could be true. Ergo, everything we do is the inevitable result of preceding causes; nothing could have happened differently. We have no agency.
This is known as causal determinism – sometimes hard determinism – and if it’s true then most of our assumptions about morality and ethics must be wrong. If someone plans and commits a horrible crime, we can’t judge them because they had no choice: their act was predetermined. No one can ever be blamed – or praised – for anything.
Few philosophers accept the hard determinist world view: it’s too bleak, too nihilistic, too incompatible with our experience as conscious agents. Instead, most philosophers endorse compatibilism: this holds that simple determinism is true – you have to throw out roughly 500 years of scientific theory for it to be wrong – but that humans still have free will.
Compatibilists believe that prior causes determine our desires and preferences but we still have the freedom to choose between them. It’s an elegant compromise: we get to keep science but don’t have to revise all our moral intuitions and reorganise our entire society to reflect our status as unwilling automata. In a 2020 survey of academic philosophers, nearly 60% were compatibilists; only 11% thought we had no free will.
But in his new book, Determined: Life Without Free Will, Sapolsky has come for the compatibilists, arguing that the past few decades of social and biological science have made their position untenable.
Instead, the intent you form, the person you are, is the result of all the interactions between biology and environment that came before. All things are out of your control. Each prior influence flows without a break from the effects of the influences before. As such, at no point in the sequence is there a place where you can insert a freedom of will that will be in that biological world but not of it.
We don’t need neuroscience to prove his point, he adds in a phone interview after Determined was released, provoking criticism and much debate. “If people reflect on it, they should come to the same conclusion when they have a cup of coffee in the morning and they suddenly think more clearly. It’s the same evidence of machine-ness underneath the surface.”
Peace among the baboons
When Sapolsky graduated from Harvard University, he began studying a group of baboons in southwest Kenya, observing them for four months a year over 25 years. They became known as the Forest Troop baboons and they made him famous.
Humans and chimps are great apes but baboons are old-world monkeys. They live in groups of 50-250 dominated by alpha males – the most aggressive and cunning male troop members, who monopolise the females and the lower-status baboons, harassing and attacking them. There’s a great deal of status conflict in baboon society as animals compete – often violently – to improve their position in the hierarchy.
In the mid-80s, Sapolsky’s troop began scavenging food from a rubbish dump. This involved fighting with another baboon troop, which meant the higher-status baboons got most of the meat – which was contaminated with bovine tuberculosis. They all died, leaving behind the females, the young and the low-status male baboons, who then set about forming a more egalitarian, harmonious society: co-operative, less violent (though still very confrontational and violent by human standards).
The new culture endured over decades: as new males from other troops entered the tribe, they either conformed to the new lifestyle or were torn to shreds. And the more relaxed culture showed up in the biomarkers: hormonal tests indicated that Forest Troop baboons experienced less stress than monkeys in neighbouring troops.
Sapolsky had demonstrated cultural evolution in a non-human species, and showed that cultural change had a profound effect on physiology.
Scientists in the 20th century spent a lot of time litigating the “nature versus nurture” debate. Was human behaviour shaped by our biology or our environment? Sapolsky is emphatic that the answer is both, and that nature and nurture interact with each other in complex feedback loops.
The turtle analogy
There’s a famous (almost certainly untrue) story about the psychologist William James delivering a lecture on cosmology and the structure of the solar system, then being approached afterwards by an elderly woman who tells him that the Earth rests on a giant turtle. When James asks what that turtle rests on, she replies, “You’re very clever, but it’s turtles all the way down.”
This is Sapolsky’s central metaphor. On a minute-by-minute basis, our brains are like the solutions of neurons in the Petri dish: molecular constructs obeying physical laws. Go down one turtle and our brains are controlled by the hormones released by our endocrine systems: just like baboons, we’re inclined towards aggression or compassion by the chemical messengers secreted into the bloodstream.
These are mediated by culture – are you born into an egalitarian society or a hierarchical, competitive one? The brain that’s generating the thoughts behind our actions was heavily influenced in utero by maternal nutrition, illness and hormones. Beneath all of this paddles the giant terrapin of genetic inheritance.
When the human genome was first sequenced in the early 2000s, the assumption about human DNA was that it was fixed: the genes you got from your parents were the ones you were stuck with.
Researchers also observed that most of the human genome consisted of “junk DNA”: non-coding regions of nucleotides that weren’t even genes at all. Much of the junk turned out to be regulatory regions: sequences that can switch genes off and on, or amplify them, or control the way genes interact with other gene products. And these respond to environmental factors.
“Suppose someone has a gene variant related to aggression,” Sapolsky suggests. “Depending on the environment, that can result in an increased likelihood of street brawling or of playing chess really aggressively. Or a gene related to risk-taking that, depending on environment, will influence whether you rob a store or gamble on founding a start-up.”
And it’s the same deal with different gene variants, he says. “One variant of the gene whose protein breaks down serotonin will increase your risk of antisocial behaviour … but only if you were severely abused during childhood. A variant of a dopamine receptor gene makes you either more or less likely to be generous, depending on whether you grew up with or without secure parental attachment. That same variant is associated with poor gratification postponement … if you were raised in poverty.”
There’s an infinite regress of cause and effect, biology and environment – turtles all the way down – and there is “no remaining gap for moral responsibility to fill”.
If all of this is true, why does every moment of our waking lives feel as if it’s false? There’s 60 years of neuroscience and cognitive psychology demonstrating that our brains make decisions before we’re aware of having made them, but the sense that we exercise conscious control is overwhelming.
Sapolsky believes this is adaptive. After all, his viewpoint is extremely depressing.
“Mood disorders like depression consist of a failure of rationalisation. A failure to self-deceive. Depression is when it’s impossible for you to put away the thought that, well, everybody’s heart is going to stop beating at some point.”
He points out that evolutionary biologist Robert Trivers has suggested that complex species evolve the ability to deceive ourselves because it enhances our ability to deceive others. “The really interesting exploration of it is if you’re going to have a species that’s smart enough to be able to extrapolate into the future, the only way we could make it is if we had a very healthy capacity for self-deception.”
He believes depression is what you get when the self-deception breaks down. Sapolsky has struggled with it for most of his life. In a footnote near the end of his book, he makes a disclosure: “At some point in this writing process, I was struck with what seemed like the explanation for why I’ve been able to stick with an unshakable rejection of free will, despite the feelings it can evoke.
“Since my teenage years, I’ve struggled with depression. Now and then, the meds work great and I’m completely free of it … Most of the time, though, the depression is just beneath the surface, kept at bay by a toxic combination of ambition and insecurity, manipulative shit and a willingness to ignore who and what matter. And sometimes it incapacitates me, where I mistake every seated person as being in a wheelchair and every child I glance at as having Down syndrome.”
Isn’t there a less morbid link between mood disorders and determinism? Maybe recurring mental illness just makes it easier to regard the brain as an organ that can malfunction rather than a free-floating, self-moving self?
He’s enthusiastic about this idea. “It’s when you get someone, say, with a long history of depression not taking meds and when they finally do and suddenly three days later something clicks and you then have a crisis of, ‘Okay, is this who I was meant to be all along? Is this, finally, a new me?’ Yeah, I think it absolutely speaks for that.”
Programmable machines
Back when Sapolsky was a depressed teenager, he woke up at two in the morning and experienced the opposite of a religious experience, concluding simultaneously that there was no god and no free will. These convictions have been with him ever since. They’re not always depressing: his universe is not a clockwork one where everything is preordained with the predictable interactions of elementary particles. Instead, it’s chaotic, subject to quantum indeterminacy. Humans are biological machines but we’re highly programmable. We can change – for better or worse. We just can’t choose to change. And underlying everything is a mathematical reality that remains mysterious.
There’s a hard problem in theoretical computer science known as the travelling salesman problem, or TSP. “Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the origin city?”
The complexity of the calculation increases exponentially with the number of cities and routes. TSP algorithms can be famously complex, but natural systems solve them all the time. Those brain cells stirred into a solution find optimally efficient ways to connect each other up. Ants in a colony solve the algorithms to find maximally efficient ways to forage for food. “The first time that I understood the algorithm for how I solved the traffic salesman problem, it was almost the point of religious ecstasy for me,” Sapolsky recalls.
Some compatibilist philosophers argue that free will is an emergent phenomenon. The same way ants can somehow solve complex algorithms, the human mind somehow breaks determinism and frees itself from biological constraints.
But, Sapolsky points out, there’s robust scientific literature describing how ants and brain cells solve optimisation problems. “No matter how emergently cool, ant colonies are still made of ants that are constrained by whatever individual ants can or can’t do, and brains are still made of brain cells that function like brain cells.” In emergent theories of free will, we acquire control by magic.
What’s more intriguing to him is that the algorithms exist at all. “It’s showing the notion of how much of maths is not being invented, but rather discovered that it’s there all along.
“Even if we were never more than paramecium [a microscopic organism]it would still be there. That is like a very cool notion to make.”
A drug to help you say no
In 2017, the US FOOD AND Drug Administration gave approval for the commercial sale of semaglutide (Ozempic), a drug developed by the Danish pharmaceutical company Novo Nordisk. Clinical trials indicated it was useful for treating type 2 diabetes, mimicking a hormone that targets areas in the brain regulating appetite and food intake. Since then, it’s become popular as a weight-loss drug, also marketed as Wegovy. It’s so lucrative that Novo Nordisk’s profits have become the primary contributor to Denmark’s economic growth.
Intriguingly, Ozempic and its family of pharmaceuticals also seem to treat other forms of addiction. Patients who take it for weight loss also report a reduction in other compulsive forms of behaviour: smoking, drinking, shopping, nail-biting. Has Novo Nordisk invented a drug that somehow gives people free will? Not exactly. The current theory is that the drug moderates reward pathways in the brain. Mice who are dosed with the drug and then given alcohol experience less of a dopamine hit, therefore less pleasure. It’s still biochemical turtles all the way down.
For Sapolsky it is “totally interesting that they fumbled into a drug. Forget doing something with gastric absorption or nutrients or something. That’s the most common way to go after weight loss. Or even doing something to satiety signals up in your hypothalamus. The fact that this is turning out to be some sort of drug that makes it easier to say no across all sorts of domains is incredibly interesting. And for anyone who’s still holding on to free-will nonsense, this is something that should stop them in their tracks.”
Stress test
“Dysevolution” describes the mismatch between our genes and the environment. The circumstances we live in today are wildly different from those of our ancestors but our genes are still those of a species of prehistoric nomadic scavengers.
Obesity is the most famous example of dysevolution: early humans suffered routine food scarcity, often dying from famine, but now we have food available to us in lethal abundance.
Robert Sapolsky thinks stress is an even more harmful dysevolutionary problem than obesity. The stress reaction evolved as a physical response to the threat of danger. When an animal is under attack, its body releases the stress hormones adrenalin and cortisol into the bloodstream, preparing the body to either fight or run, and supplying the energy to do either. It will experience heightened senses and a sharpened memory and, often, a rush of pleasure.
Modern humans aren’t attacked by lions very often. Instead, we have the ability to inflict social and psychological stress on ourselves. We replace short bursts of stress to cope with an emergency with long periods of sustained stress, and the repeated release of the stress hormones into the brain and the bloodstream inflicts long-term damage.
Loneliness is a stressor and so is poverty. Any environment in which you’re uncertain about the immediate future is stressful, and children who grow up in these environments are scarred by them; likely to have lower impulse control and higher vulnerability to depression and anxiety.
Determined: Life Without Free Will by Robert Sapolsky (Bodley Head) is available now.
