Natural beauty really entices men. They will tell you this time and time again, and studies consistently prove it.

Saliva has testosterone and estrogen. When you kiss, you're having a chemical experience.

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

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.

Romantic love is an addiction.

When you're in the throes of this romantic love, it's overwhelming - you're out of control, you're irrational, you're going to the gym at 6 A.M. every day - Why? Because she's there.

Romantic love allows you to focus mating energy. Attachment sustains that relationship as long as necessary to raise your baby.

I've always maintained that men were more romantic than women.

I think romantic love evolved to enable you to focus your mating energy on just one individual at a time, thereby conserving mating time and energy.

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

Psychologists maintain that the dizzying feeling of intense romantic love lasts only about 18 months to - at best - three years.

The reason you take antidepressants is to feel calm. And romantic love is not calm - it's elation, it's mood swings, and you're killing all that when you take the drug.

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.

We evolved in a tropical climate where the smells of plants and flowers were all around us. We spent a lot of time in the trees with a lot of sunlight and no clothes.

A hundred years ago, if you had a child out of marriage, you'd be a social disgrace. Today women feel comfortable enough economically and culturally to bring up a child without a recognized commitment from a man.

People compose poetry, novels, sitcoms - for love.

Most of us make up our minds in the first three minutes of meeting someone whether there's a potential for a relationship.

When you fight, anger drives up testosterone in both men and women.

Until recently, we regarded love as supernatural. We were willing to study the brain chemistry of fear and depression and anger but not love.

A lot of people head into courtship looking for fireworks. Don't pass up a chance by dumping someone after a first date because you don't feel the fireworks. The fireworks can happen at any time and be maintained.

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.

Men have a psychological need to show off their courage and strength. When he sees you talking to another guy, that instinct kicks in and he jumps to protect you and prove he's worthy of your love.

Both sexes like the exercise and challenge of sports, but for men it's also a basic display behavior for impressing and winning a mate.

Games are the way we keep romance alive. They're based in human hardwiring. Playing hard-to-get or leaving a little to the imagination allows the woman to be wooed and appreciated and the man to be challenged and intrigued.

In general, men are wired to notice obvious signs that convey interest in mating - a warm smile, for example - and ignore other subtleties, like if your lipstick is faded.