People have been looking for love potions since hunter-gatherer societies.

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.

In courtship, who wins and who loses will determine who passes on their DNA to tomorrow.

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

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.

Women have a better sense of smell than men do, and it's even sharper in the middle of their menstrual cycle, when estrogen levels peak and women are more likely to be deciding whether a man's attractive.

Liberals and conservatives are looking for entirely different things. Their attitudes toward romance and how they court are really dramatically different. There's almost no overlap.