The biology of our best and worst selves | Robert Sapolsky

2 min read

neuroscience society

If you want to understand a behaviour,

you should consider multiple levels of causality,

from the second before to millions of years before

An example case:

There is man running toward you and holds something that looks like a gun. You shot him

1 sec before

amygdala -> fear, excitement

Minutes before

if you are hungry or tired, frontal cortex doesn’t work well and ask you that are you sure if it is a gun

Hours to days

testesteron, stress hormones, alcohol

they are not the cause but they amplify existing tendencies

Weeks to months

neuroplasticity -> brain changes by experience, if previous months were stressful, amygdala will enlarge, and will be harder to control

Years to decades

adolescence shapes the brain , stress in childhood or as a fetus leads to larger amygdala and elevated stress hormone levels

Genes don’t determine anything because they work differently in different environments. Genes and environment interact


if ancestors are nomadic herders, mood are that they will have a culture of honor and quick to anger and revenge,

and this values can stick around for centuries

Millions of years -> evolution, some species have lower aggression levels some higher

Its complicated and be careful to conclude what causes a behavior,

especially if it’s a one you are judging harshly

Context matters

We don’t hate violence, we love it in the right context

Pulling a trigger or touching someone has very different meanings in different contexts

Every bits of biology can change and it is possible to change in a good way

Ecosystems change -> Sahara was a lush grassland

Brains change

Cultures change

People can get better

even the ones who have done bad things

We can change our worst sides,

History is full of such examples

We are able to change for the better.