The regulation of genes is often more interesting than the genes themselves, and it's the environment that regulates genes.

On an incredibly simplistic level, you can think of depression as occurring when your cortex thinks an abstract thought and manages to convince the rest of the brain that this is as real as a physical stressor.

Depression is not generalized pessimism, but pessimism specific to the effects of one's own skilled action.

Individual differences in testosterone level predict very little about differences in aggression.

The problem isn't testosterone and aggression; it's how often we reward aggression. And we do: We give medals to masters of the "right" kinds of aggression. We preferentially mate with them. We select them as our leaders.

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

We all seek out stress. We hate the wrong kinds of stress but when it's the right kind, we love it - we pay good money to be stressed by a scary movie, a roller coaster ride, a challenging puzzle.