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

Importantly, rather than promoting aggression, testosterone promotes whatever is needed to maintain status when challenged.

Essentially, we humans live well enough and long enough, and are smart enough, to generate all sorts of stressful events purely in our heads.

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

What does the frontal cortex do? Gratification postponement, executive function, long-term planning, and impulse control. Basically, it makes you do the harder thing.

Fossey, Fossey, you cranky difficult strong-arming self-destructive misanthrope, mediocre scientist, deceiver of earnest college students, probable cause of more deaths of the gorillas than if you had never set foot in Rwanda, Fossey, you pain-in-the-ass saint, I do not believe in prayers or souls, but I will pray for your soul, I will remember you for all of my days, in gratitude for that moment by the graves when all I felt was the pure, cleansing sadness of returning home and finding nothing but ghosts.

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