Of all the foods we share, there is nothing more primordial than meat. It's no surprise that meat-eaters still want a partner who will give, receive and share this primordial symbol of a budding partnership.

Women are naturally prone to compete over their mates.

Jealousy can even be good for love. One partner may feel secretly flattered when the other is mildly jealous. And catching someone flirting with your beloved can spark the kind of lust and romance that reignites a relationship.

At first I assumed hate was the opposite of love. But it isn't. The opposite of love is indifference.

Romantic love is not an emotion. ... It's a drive. It comes from the motor of the mind, the wanting part of the mind, the craving part of the mind.

As social animals, we need to exchange juicy tales about someone - to connect with one another. For millions of years our forebears must have sat around the campfire, whispering about everyone they knew.

The human brain is built to compare; it's Darwinian to consider an alternative when one presents itself.