I have a weakness for science made simple. For three years now I have been struggling through medical research and wrestling with complicated readings only to find out that what I really needed was Robert M. Sapolsky and his latest book, Behave: The Biology of Humans at Our Best and Worst.

If you ever thought that neuroscience was deathly boring or too complicated for pleasurable reading, Behave will find you literally guffawing at Sapolsky’s quirky, hipster humour, and at about 100 pages in, you’ll begin to question whether that decision you made so many years ago not to go into the sciences might have been too hasty. The book is that good. Sapolsky is so immensely comfortable explaining complicated things in accessible ways, more than once you’ll feel he’s pulling you aside to whisper, “Don’t worry, this isn’t as difficult to understand as you thought.”

“Adolescence and early adulthood are the times when someone is most likely to kill, be killed, leave home forever, invent an art form,” he writes, “help overthrow a dictator, ethnically cleanse a village, devote themselves to the needy, become addicted, marry outside their group, transform physics, have hideous fashion taste, break their neck recreationally, commit their life to God, mug an old lady, be convinced that all of history has converged to make this moment the most consequential, the most fraught with peril and promise, the most demanding that they get involved and make a difference.”

A professor of biology and neurology at Stanford University and a recipient of a MacArthur Foundation ‘genius’ grant, Sapolsky brings together a basket of scientific disciplines to tackle a fundamental mystery: What drives humans to harm each other or help each other? He finds the answers in our biology and takes readers on a journey through the nervous system, hormones, evolution and environment to make his argument.

“On a certain level the biology underlying the teenaged mugger is similar to that of the teen who joins the Ecology Club and donates his allowance to help save the mountain gorillas,” Sapolsky writes. “It’s the usual — heightened emotional intensity, craving for peer approval, novelty seeking, and oh, that frontal cortex. But that’s where similarities end.”

In a chapter titled ‘Adolescence; or Dude, Where’s My Frontal Cortex?’ — that title alone should assure you that this is not your mother’s neuroscience — Sapolsky moves briskly from the changing frontal cortex (it is, by the way, fully developed in adolescence, it just isn’t very efficient) to the neurological and environmental underpinnings of adolescent behaviour in all its forms.

“Every hiccup of experience has an effect, albeit usually a miniscule one, on that brain,” he writes. “Violent criminals are more likely than nonviolent ones to have witnessed violence as kids,” and “exposing children to a violent TV or film clip increases their odds of aggression soon after. Interestingly, the effect is stronger in girls.”

Those kinds of experiences, Sapolsky writes, aren’t universal, but rather make the strongest impression on kids who are already prone toward violence. As a general matter, “pretty straightforwardly, the more categories of adversities a child suffers, the dimmer his or her chances of a happy, functional adulthood.” I should hasten to add that Behave goes way beyond the adolescent brain; that area just happens to be my current obsession.

In a chapter called ‘Us versus Them,’ Sapolsky rolls out research showing that “fans at a soccer match are more likely to aid an injured spectator if he’s wearing home team insignias,” and he suggests that we “give the right of way to people driving cars with the ‘Mean people suck’ bumper sticker, and remind everyone that we’re all in it together against Lord Voldemort and the House of Slytherin.”

The book is filled with geeky anecdotes that Sapolsky clearly derives pleasure in telling. He writes about being a future primatologist (one of his many hats) and being mesmerised by the 1968 movie Planet of the Apes only to find out later, to his delight, that stars Charlton Heston and Kim Hunter both recounted that “at lunchtime, the people playing chimps and those playing gorillas ate in separate groups.”

He tells us that culture shapes our attitudes about success, morality and even love — no surprise there — but then he adds that research shows culture also has an effect on sensory perception. When looking at something as simple as a photograph, Westerners focus on the centre of the picture, Asians focus on the scene.

All interesting stuff, but the book’s greatest contribution may be in laying to rest many assumptions we’d made about why we do what we do. Consider the much-ballyhooed ‘warrior gene,’ the one that allegedly predisposes those who carry it to violence. Sapolsky explains that the supposed links between aggression and the MAO-A ‘warrior’ gene are far from proven, and he muses that “amazingly, prison sentences for murders have now been lessened in at least two cases because it was argued that the criminal having the ‘warrior gene’ variant of MAO-A was inevitably fated to be uncontrollably violent. OMG.” (Yes, the OMG is Sapolsky’s, not mine.)

He reminds readers that the research paper that began all the hubbub about a gene that predetermined aggression looked at a Dutch family that not only had that mutation, but also had “borderline mental retardation.” Everyone remembers the gene, Sapolsky suggests, but they have forgotten a lot of the underlying details. “Responsible people in the field have recoiled in horror at this sort of unfounded genetic determinism seeping in the courtroom,” he writes.

But wait, there’s more — as the author himself might say: Sapolsky leaves little surprises for his readers in the footnotes, which read like in-jokes from the lab. “By the way, what does mouse anxiety look like?” Sapolsky writes in one. “Mice dislike bright lights and open spaces — go figure, for a nocturnal animal that lots of species like to eat. So one measure of mouse anxiety is how long it takes for a mouse to go into the centre of a brightly lit area to get some food.”

The only hesitation is that science, by its very nature, is provisional and Sapolsky is depending on research that may already be overcome by events. The fields of psychology and neuroscience have been in upheaval in the past five years as new discoveries begin to cast doubt on what was once thought to be irrefutable. Sapolsky’s work may become entangled in those kinds of professional squabbles. That said, for any layperson trying to understand why we behave the way we do, Sapolsky has created an immensely readable, often hilarious romp through the multiple worlds of psychology, primatology, sociology and neurobiology to explain why we behave the way we do. It is hands-down one of the best books I’ve read in years. I loved it.

—By arrangement with the Washington Post

Published in Dawn, Books & Authors, August 20th, 2017