Like most animals, we're wired to associate height with power.

I don’t think we’re an animal that was built to be happy; we are an animal that was built to reproduce.

The main characteristics of romantic love are craving: an intense craving to be with a particular person, not just sexually, but emotionally.

If two very different people pool their DNA, they'll create more genetic variety, and their young will come to the job of parenting with a wider array of skills.

We're not very dangerous animals; we don't have a horn like a rhino or quills like a porcupine.

Women's worst invention was the plow. With the beginning of plow agriculture, men's roles became extremely powerful. Women lost their ancient jobs as collectors.

Men have a psychological need to show off their courage and strength. When he sees you talking to another guy, that instinct kicks in and he jumps to protect you and prove he's worthy of your love.