Anthropologists have found evidence of romantic love in 170 societies. They've never found a society that did not have it.

You can get into a very fancy car and know everything about the engine, but when you drive in that car, you feel that rush. In the same way, I think the more you know about love, the more you can enjoy it. And knowing about your personality type, who you are and what kind of person you're dealing with gives you a great leg up.

Today, American women bear an average of 2.2 children that live to adulthood. Across most of Europe, women bear even fewer young.

Blushing is thought to be linked to increased levels of norepinephrine in the brain, which may be associated with romantic feelings. It signals that we are interested and excited, which is attractive to men.

You size up someone physically in less than one second - too tall, too short, too fat, too thin, too old, too young, too stuffy, too scruffy.

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.

Romantic love is an addiction: a perfectly wonderful addiction when it's going well, and a perfectly horrible addiction when it's going poorly.