Behave: The Biology of Humans at Our Best and Worst
Started: 2026-07-18
Completed: -
Key Info
[Title] Behave: The Biology of Humans at Our Best and Worst
[Author] Sapolsky, Robert
Overview
Sapolsky explores how human biology makes us act the way we do.
Quotes
Chapter 2: One Second Before
On the amygdala
Crucially, the brain region most involved in feeling afraid and anxious is most involved in generating aggression.
… autonomic feedback influences the intensity of what is felt
Your heart does roughly the same thing whether you are in a murderous rage or having an orgasm. Again, the opposite of love is not hate, its indifference.
On the frontal cortex
"Doing the harder thing" effectively is not an argument for valuing either emotion or cognition.
On dopamine and habituation
An emptiness comes from this combination of over-the-top nonnatural sources of reward and the inevitability of habituation; this is because unnaturally strong explosions of synthetic experience and sensation and pleasure evoke unnaturally strong degrees of habituation.
On dopamine and anticipation
... once reward contingencies are learned, dopamine is less about reward than about its anticipation.
... the pleasure is in the anticipation of reward, and the reward itself is nearly an afterthought...
... dopamine is not about the happiness of reward. It's about the happiness of pursuit of reward that has a decent chance of occurring.
... there's the lure of needing neurobiology to confirm the obvious... It shouldn't require neuroscience to validate someone's internal state... It shouldn't take neuroscience to "prove" what we think and feel.
Chapter 3: Seconds to Minutes Before
On the connection between sense and emotion
Across species the dominant sensory modality—vision, sounds, whichever—has the most direct access to the limbic system.
In the moments just before we decide upon some of our most consequential acts, we are less rational and autonomous decision makers than we like to think.
Chapter 4: Hours to Days Before
On testosterone
This context dependency means that rather than causing X, testosterone amplifies the power of something else to cause X.
... watching your favorite team win raises testosterone levels, showing that the rise is less about muscle activity than about the psychology of dominance, identification, and self-esteem...
When testosterone rises after a challenge, it doesn't prompt aggression. Instead, it prompts whatever behaviors are needed to maintain status... Engineer social circumstances right, and boosting testosterone levels during a challenge would make people compete like crazy to do the most acts of random kindness. In our world riddled with male violence, the problem isn't that testosterone can increase levels of aggression. The problem is the frequency with which we reward aggression.
On the dark side of oxytocin
Oxytocin, the luv hormone, makes us more prosocial to Us and worse to everyone else. That's not generic prosociality. That's ethnocentricism and xenophobia.
Follow the Trail
- Ian McEwan’s Saturday illustrating the life of a person with Huntington’s disease (subcortical damage)
- Daniel Wegner's "How to Think Say or Do Precisely the Worst Thing on Any Occasion", an article on the effects of stress on the frontal cortex