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Insights Into the Brain, in a Book You’ll Wish You Had in College

BEHAVE
The Biology of Humans at Our Best and Worst
By Robert M. Sapolsky
790 pp. Penguin Press. $35

In 1859 Charles Darwin gave the world a theory of life. A century later, evolutionary biologists started thinking seriously about its implications for human behavior. Richard Dawkins’s “The Selfish Gene” (1976) brought the resulting insights to the general public. Souls were gone, and free will too. The master manipulators were the genes. Bodies were reduced to mere lumbering robots, and even the inner lives of our species became just one more consequence of natural selection in a materialist world.

The new view quickly came to predominate, but on its own it gave too stark an account of behavior. Melvin Konner’s “The Tangled Wing: Biological Constraints on the Human Spirit” (1982, with subsequent revisions) showed how interesting the science becomes when enriched by the wet details of genes, neurons and hormones. Konner’s erstwhile student Robert M. Sapolsky has now followed the same path. Sapolsky has produced a quirky, opinionated and magisterial synthesis of psychology and neurobiology that integrates this complex subject more accessibly and completely than ever.

Much of “Behave: The Biology of Humans at Our Best and Worst,” written by a man who disingenuously declares himself “eggheady, meek and amorphously pacifistic,” is the textbook you will regret never having had in college. The science comes with hipster humor. Sapolsky writes of Jane Goodall blowing off “everyone’s socks in the 1960s by reporting the now-iconic fact that chimps make tools.… Great, next the zoologists will report that Rafiki persuaded Simba to become the Lion King.” He summarizes a chapter called “Us Versus Them” with “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 Slytherin.” He berates us for choosing leaders using “implicit, automatic factors more suitable to 5-year-olds deciding who should captain their boat on a voyage with the Teletubbies to Candyland.” Explaining why someone who sees a movie containing physically disgusting images becomes morally judgmental unless she washed her hands first, he imagines evolution as tinkerer: “Hmm, extreme negative affect elicited by violations of shared behavioral norms. Let’s see.… Who has any pertinent experience? I know, the insula! It does extreme negative sensory stimuli — that’s like, all that it does — so let’s expand its portfolio to include this moral disgust business. That’ll work. Hand me a shoehorn and some duct tape.” This is not your mother’s professor.

Of course many people would have no idea what an “insula” is, but Sapolsky eases readers gently into the complexities of the brain by ceding most of “Behave” to the fundamentals of neurobiology. We begin in the first second before a behavior is produced, our guide taking us confidently into the amygdala, the dopaminergic system and the frontal cortex. We continue the tour with events that occur minutes, hours, days, months and years ago, finally stretching back thousands of generations to the level where Darwinian processes explain why the systems that produce behavior evolved in their particular, haphazard way. By the time the book returns from these expanding horizons it has given readers the opportunity to feel astonishingly comfortable with a rich slew of fascinating neurobiology basics.

Dutiful core themes permeate the learning. Sapolsky rebukes the sociobiologists of the 1970s for their excessive focus on genes. He hammers home the message that nerves, hormones, genes, developmental experiences and evolutionary pressures must necessarily all be understood, and that none of the relationships between such factors and any behavior is straightforward. He summarizes crisply why calling the low-activity variant of the MAO-A gene a “warrior gene” is nonsensical: “Yikes, this is complicated.” Behavioral biology is indeed complex, but Sapolsky simplifies the topic with a beautifully organized and well-stocked store of knowledge. He has such a light tone, so imperious a command of data and such a rich fund of anecdotes that we are swept swiftly along to the last third of the book.

At that point Sapolsky shifts gears by turning to a question that has nudged him throughout his career. What does all this knowledge tell us about the prospects for a more empathic, less violent world? Here he echoes many a behavioral biologist’s ambition. If physics can take us to the moon, genetics give us the Green Revolution and medicine conquer polio, can neurobiology help us all get along? Sapolsky sees grounds for optimism. His hopes are admirable but they flatter to deceive.

He starts safely enough. He warns against misleading metaphors: Selfish genes do not mean selfish individuals. He exposes determinist ideas as false: Behavioral tendencies are strongly shaped by experience. He reviews evidence that societies vary in their nature and frequency of violence. He explains a series of mechanisms for the evolution of cooperation and morality. He tells how the First World War included a Christmas truce. This is worthy, reassuring stuff maintained in fine professorial style and serving to remind us that darkness is not inevitable.

But his positive thinking is not derived from brain research, nor are his prescriptions. Sapolsky proposes 10 strategies for reducing violence, all reasonable but none that justify the notion that science is the basis for societal advances toward less violence and higher morality. Promote trade and cultural diffusion. Use religion wisely. Note that punishment can sustain cooperation. Remember that humans can reconcile, just as animals can. Take advantage of the fact that it is hard to kill people you can see.

Sapolsky’s list offers no practical recipes beyond implying that once we understand that we are all creatures of flesh and blood we should all be more forgiving of each other. His omission is understandable. We are far from solving the problem.

In this section Sapolsky becomes a partisan critic, including presenting a skeptical view about the supposed long-term decline of human violence claimed by Steven Pinker in “The Better Angels of Our Nature: Why Violence Has Declined.” Sapolsky asserts that Pinker’s calculations include elementary errors, and that low rates of violence among contemporary hunter-gatherers mean that warfare did not predate agriculture. His arguments here are unbalanced. He fails to note that data on hunter-gatherer violence is relevant only where they are neighbored by other hunter-gatherers, rather than by militarily superior farmers.

But he seems to feel that if he is to maintain his positive stance he must credit the human species with an evolutionary legacy of nonviolence. So violence has to come mainly from influences that are too recent to have had major evolutionary impacts, such as agriculture (which began some 10,000 years ago), the root of a whole lot of bad things including the dogs of war: “One of the all-time human blunders, up there with, say, the New Coke debacle and the Edsel.”

The irony is that such concerns are unnecessary. A peace-loving researcher does not have to believe that ancient humans were less violent than we are, or that a better society depends on the lessons of brain science. History leaves no doubt about the cultural capacity for improvement, regardless of neurobiological insights.

When Sapolsky discusses the impact of brain science on our attitude to parenting, he gets the relationship exactly right. “It shouldn’t require molecular genetics or neuroendocrinology factoids,” he writes, “to prove that…it profoundly matters to provide childhoods filled with good health and safety, love and nurturance and opportunity.” Nor should it require neurobiology factoids to prove that we can make society increasingly moral. Still, if people find inspiration from them, as Sapolsky writes, “more power to these factoids.”

If it took an unrealistic connection between science and society to motivate Sapolsky to write “Behave,” that is a small price. His book offers a wild and mind-opening ride into a better understanding of just where our behavior comes from. Darwin would have been thrilled.