Your sweetheart calls you by another's name. His eyes linger too long on your best friend. He talks with excitement about a girl at work. And the fire catches. Jealousy - that sickening combination of possessiveness, suspicion, rage, and humiliation - can overtake your mind and threaten your very core as you contemplate your rival.

Men and women are like two feet; they can help each other get ahead.

What our grandmothers told us about playing hard to get is true. The whole point of the game is to impress and capture. It's not about honesty. Many men and women, when they're playing the courtship game, deceive so they can win. Novelty, excitement and danger drive up dopamine in the brain. And both sexes brag.

When people tell you to walk a certain way, it's like not thinking of a purple tomato. You can't not do it.

Romantic love allows you to focus mating energy. Attachment sustains that relationship as long as necessary to raise your baby.

As a group, anthropologists are not too fond of people who work in the business world.

I think romantic love evolved to enable you to focus your mating energy on just one individual at a time, thereby conserving mating time and energy.