It's probably even the case that if you stoked up some Buddhist monks with tons of testosterone, they'd become wildly competitive as to who can do the most acts of random kindness.

Stress is not a state of mind... it's measurable and dangerous, and humans can't seem to find their off-switch.

Oxytocin is lauded for how it promotes warmth, generosity, social bonding, cooperation, trust, and compassion.

We're getting along so well; I trust you so much for this one second that I'm going to let you yank on me.

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.

Hormones influencing the sensitivity of the person to environmental stimuli.

How much you groom somebody else is more important than who grooms you.