Science
by Robert Sapolsky
What makes us kind or cruel?
We don't object to violence as such, Robert Sapolsky points out. We praise a soldier who fights to save lives and condemn a mugger. Sapolsky, a neuroscientist who spent years studying baboons, wants to explain the biology behind our best and worst acts, and why they can look so alike.
Hear a sample · read by Laura
Start with the brain in the moment. The amygdala flags threats, often before you notice them. The frontal cortex, the brain's planner, can overrule an impulse when the hard option is the right one. Dopamine drives you towards rewards you expect. Behaviour comes out of their tug of war.
Hormones set the brain's mood. Sapolsky says testosterone rarely creates aggression from nothing. It makes people readier to do whatever wins status in that setting, which is sometimes being generous. Stress hormones, if they stay high for weeks, wear down the frontal cortex and make the amygdala jumpier.
The frontal cortex is the last part of the brain to finish maturing, in the mid-twenties. Teenagers feel intensely before their brakes are fitted. Further back, childhood stress and even the womb shape how that brain gets built. Genes matter too, but their effects depend on the environment they meet.
The brain sorts people into Us and Them fast. We'll favour Us even when the groups are pointless, split over which of two painters people preferred. But the lines move. We all belong to many groups, and Sapolsky shows that changing which one feels important can soften the divide.
Zooming out
To explain one act, Sapolsky looks back in steps, from the brain a second before to our evolution long ago.
Testosterone
Testosterone doesn't create aggression. It turns up tendencies a person already has.
Oxytocin
Oxytocin makes us warmer to our own group and colder to outsiders.
Frontal cortex
The frontal cortex helps us do the harder, right thing, and it isn't fully built until our mid-20s.
Genes
Genes don't decide behaviour on their own. They work through the world we grow up in.
A story from the book
Sapolsky studied a baboon troop in Kenya whose most aggressive males fed at a tourist lodge's rubbish dump. They caught tuberculosis from tainted meat there and died. The troop left behind was unusually gentle, and years later it still was, as new males joined and picked up its ways.
Hot take · true or myth?
Dopamine is the brain's pleasure chemical, released when you get what you want.
Myth. Sapolsky says dopamine is more about wanting than getting. It rises as you anticipate a reward, and most of all when the reward is only a maybe, which helps explain gambling.
One thing to try
Pick someone you'd file under Them, say a rival team's fan or a neighbour whose politics annoy you. This week, find two things you share with them, like a hometown or a job. In the studies Sapolsky describes, a shared identity makes the old split matter less.
Knotd has the key ideas from 250+ non-fiction books, each in a few minutes, in plain words. Behave comes with a Hot Take round and a Name That Idea round to make it stick.
Get the whole book on KnotdOpen in the appWhat makes us kind or cruel? We don't object to violence as such, Robert Sapolsky points out. We praise a soldier who fights to save lives and condemn a mugger. Sapolsky, a neuroscientist who spent years studying baboons, wants to explain the biology behind our best and worst acts, and why they can look so alike.
One second before; Hours to months before; Years before, even the womb; Us and Them.
Pick someone you'd file under Them, say a rival team's fan or a neighbour whose politics annoy you. This week, find two things you share with them, like a hometown or a job. In the studies Sapolsky describes, a shared identity makes the old split matter less.
Yes. Knotd has the key ideas from Behave in a few minutes, in plain words, plus a Hot Take round and a Name That Idea round to test them. It's one of 250+ non-fiction books in the app.
