You fall in love with somebody who fits within what I call your 'love map,' an unconscious list of traits that you build in childhood as you grow up. And I also think that you gravitate to certain people, actually, with somewhat complementary brain systems.

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.

Kissing is not just kissing. It is a major escalation or de-escalation point in a powerful process of mate choice.

Women apparently are quite drawn to men who have differences rather than similarities in their histocompatibility system. They pick it up by smell, and they can pick it up from kissing.

From my studies of genetics and neuroscience I have come to believe that people fall into four broad personality types - each influenced by a different brain chemical: I call them the Explorer, Builder, Director, and Negotiator.

A world without love is a deadly place.

You've got to remember that men are men and women are women. And although a lot of similarities, there are some real differences.