Naturally, things are more complicated - those groovy, pro-social effects of oxytocin apply to how we interact with in-group members.

The fascinating thing about our best and worst behaviors isn't the behavior itself - the brain tells the muscles to do something or other - big deal. It's the meaning of the behavior.

Digestion is quickly shut down during stress…The parasympathetic nervous system, perfect for all that calm, vegetative physiology, normally mediates the actions of digestion. Along comes stress: turn off parasympathetic, turn on the sympathetic, and forget about digestion.

For example, most mammals are either monogamous or polygamous. But as every poet or divorce attorney will tell you, humans are confused - After all, we have monogamy, polygamy, polyandry, celibacy, and so on. In terms of the most unique thing we do socially, my vote goes to something we invented alongside cities - we have lots of anonymous interactions and interactions with strangers. That has shaped us enormously.

Get it wrong, and we call it a cult. Get it right, in the right time and the right place, and maybe, for the next few millennia, people won't have to go to work on your birthday.

Brains distinguish between an Us and a Them in a fraction of a second. Subliminal processing of a Them activates the amygdala and insular cortex, brain regions that are all about fear, anxiety, aggression, and disgust.

Perhaps most excitingly, we are uncovering the brain basis of our behaviors - normal, abnormal and in-between. We are mapping a neurobiology of what makes us us.