Robert Sapolsky, who looks like Jerry Garcia would if Jerry Garcia were still alive, is a rock star of neuroscience. He’s just one of those people—when he was a kid fascinated with primates he started, at age 13, teaching himself Swahili so he could go to Africa to study them. Now 60, Sapolsky is a cross-appointed professor at Stanford University (biology and neuroscience), and a research associate at the National Museums of Kenya. Along the way, he picked up a MacArthur genius award. His latest book is Behave: The Biology of Humans at Our Best and Worst, a masterful synthesis of current scientific thinking on the biological roots of our behaviour.

The perspective is gripping. It starts with any human moment, good or bad—touching another’s arm or pulling a trigger. Make no assumptions about which is the good deed. Touching can lead down a dark road and pulling the trigger may be in defence of the helpless. Sapolsky has two mantras running through his 700 pages—“context, context, context” and “it’s complicated.” From whatever starting point, he then peels outwards and backwards. What was going through the brain a second before the behaviour; what stimulus, experienced minutes before, prompted the response; what hormones had been in action hours or days earlier, what structural changes had recently occurred—what, in fact, is the sum total of childhood experience, fetal experience, and genetic make-up? How did culture shape the individual’s group, and what environment shaped that culture? And on and on, back for millions of years.

Just about everything Sapolsky touches on is hot-button politics, from questions of free will and criminal responsibility (he’s written extensively on “neurolaw”) to xenophobia and tribalism, war and peace, to the co-evolution of culture and brain. We are the sum of our parts, and much, much more, as Sapolsky explains.

It is complicated, isn’t it?

Yeah, everything. It’s complicated because we’re every inch of the way biological organisms and lots of people have trouble accepting that. It’s complicated because there is an enormous causative pull towards deciding our behaviour can be entirely understood by focusing on one part of the brain or one gene or one hormone or one early experience, when you’re really not going to get anywhere unless you look at the interactions of all of those. It’s complicated because there’s a very strong tendency to want to come up with attributions that involve harsh judgments for behaviour instead of remembering that we are all subject to biological forces we have very little control over. So, yeah: complicated.

Is that because we’re the ultimate split-the-difference species? Some primates are monogamous, some are promiscuous, then there’s us. We hate violence, except when we like it. We go down the middle.

We’re right down the middle in so many different ways. That’s what allows us to live in so many different ecosystems, to have so many different mating systems and so many different cultures. It’s all very charming, all that diversity stuff, but it also means we’re a terribly confused species.

We’re also very attuned to Us versus Them. That comes natural to us?

It does, and the thing that really gets me with it is that it’s simultaneously the most damned discouraging fact about us as a species while nonetheless containing enormous grounds for optimism. We are so hardwired to dichotomize into Us and Them and to automatically decide Us is better in all sorts of irrational ways and to decide we really don’t like the Them a whole lot. The strength of the dichotomizing can be seen in how quickly and unconsciously the brain processes group differences (a few hundred milliseconds to distinguish by race), how soon it emerges in young children—who by three or four years group people by race and gender and perceive other-race faces as angrier—and our tendency to group by arbitrary markers like dress, markers that are imbued with power. So, it’s inevitable—except it’s so easy to manipulate people as to who counts as Us or Them. We just change those categories within seconds. It is easy to get us to switch categories as to who is subject to all that xenophobia.

We can expand our Us to quite a large group, yes, but do you think we still need to have someone on the outside? If it’s all of humanity, then do we require aliens, somebody to contrast?

My take on that is it would be nice if we just decided it was all of us against the House of Slytherin, but maybe we do need a certain sort of consistent level of Themness. The most depressing finding of that entire literature is how almost automatically a substantial subset of us when looking at pictures of faces have all sorts of automatic categorization of faces by race. Oh my God, isn’t that depressing? Yet if those faces are wearing baseball caps with the logo from your team you instantaneously re-categorize who’s an Us and who’s a Them and you pay no attention to skin colour. Us versus Them is just a rapid and malleable system, which makes sense because we as a species belong to multiple hierarchies and multiple groups and multiple identifications. You’d better be able to very rapidly switch.

The cognitive part, the rationalizations about why we hold our prejudices, come after the instincts.

Very much so. One of the hottest topics in moral neuroscience is moral decision-making—how much are we thinking our way to a moral stance versus how much are we automatically feeling our way to it and then filling in the cognitive rationalizations. It’s a whole lot more of the latter than most people would like to think.

You go down the middle too on the co-evolution of brains and culture. On one side you dismiss those who deny the role of biology.

These are people who sarcastically refer to molecular fundamentalism, for whom it just makes no sense to ask what a gene does outside of the context of the particular environment you’re studying, even if you come up with some circus trick where you can show a gene working differently in different environments. What that misses is that most organisms are only in a very limited number of environments—thus most genes really do have a very narrow range of effects. But then you look at a species that lives in deserts and rain forest, in monogamous societies and in polygamous ones, in capitalist worlds and in socialist worlds. If there’s any species that is going to be more subject to genes working radically different in very different environments it’s humans. But they think it’s biological determinism.

But you’re not a full-on sociobiologist either. Biology is not nothing, but it’s not everything.

Selection and kin selection and self-esteem stuff can explain absolutely everything about human behaviour until the first time you look at some religion that is celibate. Or the first time you see somebody adopting a child from the other side of the planet, or the first time you see somebody holding a door open for somebody else at an airport in a city they’re about to leave and never set foot in again. As soon as you see those behaviours all the strict sociobiological models just go down the drain.

The co-evolution of culture and brains is such a loaded topic, is it not? That’s the playground that “scientific” racists work in too. They determine the tendencies and potentialities of whole populations to their environmental and “civilizational” histories. Do you worry about talking about these things? Do you get grief from either side?

I say over and over, ad nauseam, until they’re rolling their eyes, that all of what I write about are statistical patterns, all are trends. All come with massive overlaps in the distributions and with dramatic exceptions. There is as little inevitability and determinism when you look at the endocrine effects on behaviour or the cultural effects or the prenatal effects as with the genetic effects. They’re all propensities. They’re all interactive. Very little ever comes out in the form of strict determinism.

You write about the much-studied differences between people in collectivist East Asian cultures and Americans, who live in “the mother of all individualist cultures.” That includes the 7R variant on the DRD4 gene, associated with novelty-seeking and impulsivity, that runs in 23 per cent of the population in the West and one per cent in East Asia. Where do Asian Americans stand? Do they become Americans genetically, at least as far as 7R goes, as well as behaviourally?

Most of the studies show that within a generation or two of immigrating, people have taken on the cultural attributes of where they are. Changes in 7R have not been documented to my knowledge, but within a generation or two later, East Asian Americans probably still have a fairly low incidence of that variant on the D4 receptor. Thus if there is already a striking difference between East Asian kids and their great grandparents, you couldn’t ask for a clearer demonstration that the genes are not determinating.

Pastoralists tend to have a judgmental God and an honour culture, particularly desert pastoralists.

Yeah, but then again you can find somebody living in a suburb of Atlanta who has an honour mindset and it’s been God knows how many generations since his ancestors were herding sheep in the Scottish borders and fighting off sheep rustlers. Stuff can change very rapidly, but residues can last for many generations. What you see with each generation is more and more exceptions to these patterns.

Health inequality shows, no surprise, that the poor have worse health; but the outcome doesn’t seem to correlate to absolute poverty or to access to healthcare. It’s situational?

Health is worse every step you go down the socioeconomic ladder in a place like the United States, so it’s not about the really poor versus everybody else. So is it because people have less health care access at each step? No, the same gradient is in countries with universal healthcare, and you see the same thing for diseases where it wouldn’t matter how much health care access you have. Sort through the next obvious explanation: the poor have more health risk factors because they live closer to toxic dumps and they don’t belong to health clubs and they smoke more often and they’re less likely to have helmets with their bicycles. But you control for that and find it only explains a small amount of the variability. When you really sift through this enormous and careful literature, a ton of it just has to do with the mindset that comes with being poor: bad health is much more about feeling poor than it is about being poor. It’s about how much control and how much predictability you feel you have in your life. Are you or are you not efficacious in your society—that’s the pathway linking socioeconomic status to poor health, far more so than whether you can afford to belong to a health club. And it’s far worse in conditions of inequality.

That was illustrated by the stats on air rage incidence: the more people have to march through first class to get to economy, the higher it rises. Ironically, when the proletariat file through, the incidence rises among first-class passengers as well.

In other words, to the extent that this is a microcosm for the universe, resentment accounts for an awful lot of the world’s ills but a sense of entitlement accounts for far more of them.

Is the adolescent brain more prone to violence or just more prone to being impulsive?

Absolutely more prone to violence but also more prone to acts of great empathy. More prone towards everything, in fact, to every extreme of best and worst behaviours because the highs are higher and the lows are lower. It’s a gyroscope that doesn’t have a frontal cortex, which is meant to stabilize. The greatest crime fighting event on earth is the 30th birthday: antisocial behaviour becomes much more blunted with age; but at the same time the greatest likelihood of people deciding they really can look the other way from somebody else’s problems also is a 30th birthday. The extremes of adolescence and early adulthood behaviour are responsible for some of our worst moments and some of our best moments, certainly accounting for our most of the breakthroughs in math and physics and composing.

The later a brain region develops the more it’s influenced by environment rather than genes?

Yes, and the frontal cortex is the part of our brain that’s most free from genes and genetic influence. The visual cortex is basically wired up by the time you’re three years old, same thing with the auditory cortex and then there’s the frontal cortex taking another twenty years after that. It’s exactly the same hardware., so why does it take decades longer for the frontal cortex to wire up? It’s been selected for delayed maturation simply because it is never going to function properly if you don’t have 25 years to learn social mores and situational ethics and context and all the reasons why the rules that are the rules that are the rules nonetheless probably don’t apply in this special circumstance and here is why.

You’ve written a lot about neurology and the law. You’re not really impressed with the concept of free will.

Nah. I used to be polite and say stuff like I certainly can’t prove there isn’t free will. But no, there’s none. There simply is nothing compatible with a 21st century understanding of how the physical laws of the universe work to have room for some sort of volitional little homunculus crawling around in our heads that takes advice from the biological inputs but at the end of the day goes and makes this independent decision on its own. It’s just not compatible with anything we understand about how biology works. All that free will is, is the biology we don’t understand yet. If you’re willing to look at the trajectory of what’s happened with knowledge, anything that still counts as free will we’re going to have an explanation for at some point soon.

You at least extend that—there are people willing to accept no free will in terms of understanding/forgiving terrible acts—but you point out the ideas means all the good stuff we do is not free will—originated either.

That one’s really going to be tough. If somebody compliments you on what a great outfit you’re wearing today it’s really, really hard for us to respond how, no, actually the rods and cones in your eyes are of the type that keep you from putting on clothing that clashes in colour and thank God you had the economic advantages to learn to wear this and not that and afford this and not that. Instead you just say oh, thanks. Thanks, wow. I’m responsible for that. That’s all my doing. It won’t matter as much as it does when it comes to deciding what to do with people and their criminal behaviour. That’s the domain where you really do have to do the hard work to remember how much of what we do is a biological phenomenon.

Do you think the whole field of criminal law will need to be changed?

Trashed is the word that comes to mind. The criminal justice system… when you think about it the word justice doesn’t make any sense there. It’s the realm where it is going to be hardest for people to really think through how it’s got to be conceptualized totally differently.

Context, context, context.

Exactly.

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