Behave: The Biology of Humans at Our Best and Worst

by Robert M. Sapolsky

In the prior year he had seen doctors, complaining of severe headaches and violent impulses (e.g., to shoot people from the campus tower).

This is a sprawling portfolio. I will group these varied functions under a single definition, pertinent to every page of this book: the frontal cortex makes you do the harder thing when it’s the right thing to do.

After all, reward coding must accommodate the rewarding properties of both solving a math problem and having an orgasm.

What was an unexpected pleasure yesterday is what we feel entitled to today, and what won’t be enough tomorrow.

It was organized around three themes: the hub of fear, aggression, and arousal centered in the amygdala; the hub of reward, anticipation, and motivation of the dopaminergic system; and the hub of frontal cortical regulation and restraint of behavior.

Now we come to the “broken window” theory of crime of James Q. Wilson and George Kelling.38 They proposed that small signs of urban disarray—litter, graffiti, broken windows, public drunkenness—form a slippery slope leading to larger signs of disarray, leading to increased crime. Why? Because litter and graffiti as the norm mean people don’t care or are powerless to do anything, constituting an invitation to litter or worse.

Showing that testosterone causes aggression requires a “subtraction” plus a “replacement” experiment. Subtraction—castrate a male. Do levels of aggression decrease? Yes (including in humans). This shows that something coming from the testes causes aggression. Is it testosterone? Replacement—give that castrated individual replacement testosterone. Do precastration levels of aggression return? Yes (including in humans). Thus, testosterone causes aggression. Time to see how wrong that is.

Testosterone also increases confidence and optimism, while decreasing fear and anxiety.5 This explains the “winner” effect in lab animals, where winning a fight increases an animal’s willingness to participate in, and its success in, another such interaction.

Among men in stable relationships, oxytocin increased their distance from the woman an average of four to six inches. Single guys, no effect. (Why didn’t oxytocin make them stand closer? The researchers indicated that they were already about as close as one could get away with.)

Obviously, oxytocin and vasopressin are the grooviest hormones in the universe.* Pour them into the water supply, and people will be more charitable, trusting, and empathic. We’d be better parents and would make love, not war (mostly platonic love, though, since people in relationships would give wide berths to everyone else). Best of all, we’d buy all sorts of useless crap, trusting the promotional banners in stores once oxytocin starts spraying out of the ventilation system. Okay, time to settle down a bit.

And now to really upend our view of these feel-good neuropeptides. For starters, back to oxytocin enhancing trust and cooperation in an economic game—but not if the other player is anonymous and in a different room. When playing against strangers, oxytocin decreases cooperation, enhances envy when luck is bad, and enhances gloating when it’s good.

Get this: In many mammals erections are a sign of dominance, of a guy strutting his stuff. Among hyenas it’s reversed—when a female is about to terrorize a male, he gets an erection. (“Please don’t hurt me! Look, I’m just a nonthreatening male.”)*

Feeling better by abusing someone innocent, or thinking more about your own needs, is not compatible with feeling empathy. Does stress decrease empathy? Seemingly yes, in both mice and humans. A remarkable 2006 paper in Science by Jeffrey Mogil of McGill University showed the rudiments of mouse empathy—a mouse’s pain threshold is lowered when it is near another mouse in pain, but only if the other mouse is its cagemate.82

Think about this—adolescence and early adulthood are the times when someone is most likely to kill, be killed, leave home forever, invent an art form, 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, or 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. In other words, it’s the time of life of maximal risk taking, novelty seeking, and affiliation with peers. All because of that immature frontal cortex. THE

By adolescence, people are typically pretty good at perspective taking, seeing the world as someone else would. That’s usually when you’ll first hear the likes of “Well, I still disagree, but I can see how he feels that way, given his experience.”

even if there is less crying over spilled milk, there is no less cleaning required.*

the greatest crime-fighting tool is a thirtieth birthday.

Stage 5: It depends. What circumstances placed the cookie there? Who decided that I shouldn’t take it? Would I save a life by taking the cookie? It’s nice when clear rules are applied flexibly. Now the judge would think: “Yes, the bank’s actions were legal, but ultimately laws exist to protect the weak from the mighty, so signed contract or otherwise, that bank must be stopped.” Stage 6: It depends. Is my moral stance regarding this more vital than some law, a stance for which I’d pay the ultimate price if need be? It’s nice to know there are things for which I’d repeatedly sing, “We Will Not Be Moved.” This level is egoistic in that rules and their application come from within and reflect conscience, where a transgression exacts the ultimate cost—having to live with yourself afterward. It recognizes that being good and being law-abiding aren’t synonymous. As Woody Guthrie wrote in “Pretty Boy Floyd,” “I love a good man outside the law, just as much as I hate a bad man inside the law.”* Stage 6 is also egotistical, implicitly built on self-righteousness that trumps conventional petty bourgeois rule makers and bean counters, The Man, those sheep who just follow, etc. To quote Emerson, as is often done when considering the postconventional stage, “Every heroic act measures itself by its contempt of some external good.” Stage 6 reasoning can inspire. But it can also be insufferable, premised on “being good” and “being law abiding” as opposites.

Harlow provided another important lesson, thanks to another study painful to contemplate. Infant monkeys were raised with chicken-wire surrogates with air jets in the middle of their torsos. When an infant clung, she’d receive an aversive blast of air. What would a behaviorist predict that the monkey would do when faced with such punishment? Flee. But, as in the world of abused children and battered partners, infants held harder.