Behave: The Biology of Humans at Our Best and Worst

Author: Robert M. Sapolsky

• This is a central point of this book—we don’t hate violence. We hate and fear the wrong kind of violence, violence in the wrong context.

• This is a central point of this book—we don’t hate violence. We hate and fear the wrong kind of violence, violence in the wrong context. Because violence in the right context is different. We pay good money to watch it in a stadium, we teach our kids to fight back, we feel proud when, in creaky middle age, we manage a dirty hip-check in a weekend basketball game.

• This book explores the biology of violence, aggression, and competition—the behaviors and the impulses behind them, the acts of individuals, groups, and states, and when these are bad or good things.

• The goal of this book is to avoid such categorical thinking. Putting facts into nice cleanly demarcated buckets of explanation has its advantages—for example, it can help you remember facts better. But it can wreak havoc on your ability to think about those facts. This is because the boundaries between different categories are often arbitrary, but once some arbitrary boundary exists, we forget that it is arbitrary and get way too impressed with its importance.

• In other words, when you think categorically, you have trouble seeing how similar or different two things are. If you pay lots of attention to where boundaries are, you pay less attention to complete pictures.

• A behavior has just occurred. Why did it happen? Your first category of explanation is going to be a neurobiological one. What went on in that person’s brain a second before the behavior happened? Now pull out to a slightly larger field of vision, your next category of explanation, a little earlier in time. What sight, sound, or smell in the previous seconds to minutes triggered the nervous system to produce that behavior? On to the next explanatory category. What hormones acted hours to days earlier to change how responsive that individual was to the sensory stimuli that trigger the nervous system to produce the behavior? And by now you’ve increased your field of vision to be thinking about neurobiology and the sensory world of our environment and short-term endocrinology in trying to explain what happened.

• A behavior has just occurred. Why did it happen? Your first category of explanation is going to be a neurobiological one. What went on in that person’s brain a second before the behavior happened? Now pull out to a slightly larger field of vision, your next category of explanation, a little earlier in time. What sight, sound, or smell in the previous seconds to minutes triggered the nervous system to produce that behavior? On to the next explanatory category. What hormones acted hours to days earlier to change how responsive that individual was to the sensory stimuli that trigger the nervous system to produce the behavior? And by now you’ve increased your field of vision to be thinking about neurobiology and the sensory world of our environment and short-term endocrinology in trying to explain what happened. And you just keep expanding. What features of the environment in the prior weeks to years changed the structure and function of that person’s brain and thus changed how it responded to those hormones and environmental stimuli? Then you go further back to the childhood of the individual, their fetal environment, then their genetic makeup. And then you increase the view to encompass factors larger than that one individual—how has culture shaped the behavior of people living in that individual’s group?—what ecological factors helped shape that culture—expanding and expanding until considering events umpteen millennia ago and the evolution of that behavior.

• Maybe I’m just pretentiously saying, “You have to think complexly about complex things.” Wow, what a revelation. And maybe what I’ve been tacitly setting up is this full-of-ourselves straw man of “Ooh, we’re going to think subtly. We won’t get suckered into simplistic answers, not like those chicken-crossing-the-road neurochemists and chicken evolutionary biologists and chicken psychoanalysts, all living in their own limited categorical buckets.”

• It can be far more than a mere academic matter when a scientist thinks that human behavior can be entirely explained from only one perspective.

• House two female rats together, and over the course of weeks they will synchronize their reproductive cycles so that they wind up ovulating within a few hours of each other. Try the same with two human females (as reported in some but not all studies), and something similar occurs. It’s called the Wellesley effect, first shown with roommates at all-women’s Wellesley College.

• Finally, sometimes the only way to understand our humanness is to consider solely humans, because the things we do are unique. While a few other species have regular nonreproductive sex, we’re the only ones to talk afterward about how it was.

• Is “aggression” about thought, emotion, or something done with muscles? Is “altruism” something that can be studied mathematically in various species, including bacteria, or are we discussing moral development in kids? And implicit in these different perspectives, disciplines have differing tendencies toward lumping and splitting—these scientists believe that behavior X consists of two different subtypes, whereas those scientists think it comes in seventeen flavors.

• Hot-blooded badness, warmhearted goodness, and the unnerving incongruity of the cold-blooded versions raise a key point, encapsulated in a quote from Elie Wiesel, the Nobel Peace Prize winner and concentration camp survivor: “The opposite of love is not hate; its opposite is indifference.”