Review of Behave: The Biology of Humans at Our Best and Worst. By Robert M. Sapolsky. Penguin Press. 790 pp. $35.
Behave should be required reading for anyone—and everyone—interested in why human beings believe what they believe and do what they do. A door-stopper of a book, which may well take all summer to read, Behave is breathtaking in the depth and breadth of the subjects it tackles (including, but by no means limited to, neurobiology, genetics. sociobiology, prenatal sex differences, adolescence, hunter-gatherer societies, empathy, altruism, “us versus them,” war and peace, and free will) and the multi-disciplinary knowledge that Robert Sapolsky (a professor of biology and neurology at Stanford University, the recipient of a MacArthur Foundation "genius grant,” and the author of A Primate’s Memoir, Why Zebras Don’t Get Ulcers, and The Trouble With Testosterone) brings to them.
The analytic framework of Behave is at once simple and sophisticated. “Brains and cultures evolve,” Sapolsky emphasizes. “Genes are not about inevitabilities; they’re about potentials and vulnerabilities.” On their own, “they don’t determine anything.” They “have different effects in different environments...Context, context, context.” Noting how often even the most sophisticated researchers confuse causes, consequences, and correlates, Sapolsky maintains that human beings “are constantly being shaped by seemingly irrelevant stimuli, subliminal information, and internal forces we don’t know a thing about.”
Behave is full of bold claims, leavened with self-deprecating humor. The invention of agriculture was a colossal blunder, Sapolsky writes, “up there, let’s say,” with the Edsel and the New Coke. By making human beings dependent on a few domesticated crops and animals, agriculture created vulnerabilities to droughts, blights, and zoonotic diseases; encouraged sedentary living; and created surpluses that generated differences in socioeconomic status “that dwarf anything that other primates cook up with their hierarchies.” But, then again, he concludes, “Maybe this is a bit over the top.”
Sapolsky also provides a brutally candid examination of the concept of free will. Quoting artificial intelligence pioneer Marvin Minsky—“free will consists of internal forces I do not understand”—Sapolsky suggests that we embrace the concept because “we have this terrible human need for agency…And know next to nothing about those internal forces,” including, for example, the impact of brain damage on a accused serial killer. That said, Sapolsky “can’t really imagine how to live your life as if there is no free will.”
To make his case that the biology of behaviors is “in all cases, multifactorial,” Sapolsky draws on hundreds of fascinating empirical studies. Once reward contingencies are learned, he writes, dopamine release “is less about reward than its anticipation.” Alcohol evokes aggression only in those prone to aggression – or those who believe that alcohol evokes aggression (“once more showing the power of social learning to shape biology”). Oxytocin, “the luv hormone,” makes individuals more prosocial to people like them “and worse to everyone else.” And, according to Sapolsky, “genes are nearly irrelevant to the cognitive development” of children growing up in abject poverty, because poverty’s impact trumps the genetics; and genes don’t affect alcohol use as much for individuals raised in religious environments where drinking is condemned.
Context, Sapolsky demonstrates, also shapes Us/Them dichotomies. Amygdala activation increases, for example, when white subjects look at black faces while rap music is playing in the background; it’s reduced if heavy metal (associated with negative white stereotypes) is played instead. Wealthy people are more likely to see the social benefits of greed, view class hierarchies as fair, and deem success as “earned”: they are less likely to stop for pedestrians at crosswalks.
After citing the work of Stanley Milgram and Philip Zimbardo on conformity and obedience to authority, Sapolsky points out that compliance decreases when the victim is individuated (and plummets if the administrator of punishment shook hands with him or her). Women, he notes, resist demands to obey more than men. And the presence of someone else pushing back “can be galvanizing.” Most important, Sapolsky maintains that “heroism” is often “more accessible and less rarified than assumed.”
The findings I have highlighted merely scratch the surface of the insights contained in Behave. In this landmark publication, Sapolsky asks the most fundamental questions about the neurobiological and cultural roots of our thoughts and actions, tells us what we know and don’t know, and makes the experience as enjoyable as it is instructive.