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.

Men want to think women don't cheat, and women want men to think they don't cheat, and therefore the sexes have been playing a little psychological game with each other.

Any kind of novelty or excitement drives up dopamine in the brain, and dopamine is associated with romantic love.

Women spend their lives trying to look good for men. So a woman who feels she's sending the right visual signals is pleased with herself.

Scientists know that women gravitate to men who have a different immune system from theirs.

For so many generations, a woman's only career path was to marry well and to marry up. Those days have changed.

There exists no culture in which adultery is unknown, no cultural device or code that extinguishes philandering.