There's biology in everything, even when you're feeling spiritual.

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

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.

When chimps threaten, they open their mouth and show their teeth. It's a little like waving a knife in front of you. It's very primitive, and therefore bizarre.

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

Keep an open heart. We are wired to find love.

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.