It Helps You Pick a Mate
Yep, it really is "in his kiss." Your lips are packed with nerve endings, and when you lean in for a smooch, your brain registers everything from your mate's taste to his temperature. Not only that, but your saliva contains a cocktail of hormones (dopamine, serotonin, estrogen and testosterone) that can tell you more about your partner's temperament than any first date conversation. All these sensations will cause your brain to give your new guy or gal the green light or send you running in the other direction.