BBC NEWS | Science & Environment | Complex clues in a kiss

BBC NEWS | Science & Environment | Complex clues in a kiss: "When you share a kiss with your lover on Valentine's Day, you may be revealing a lot more than you realise.

Locking lips not only stimulates our senses, it also gives us subtle clues about our suitability as mates, US scientists have found.

A man's saliva has a 'cocktail of chemicals' hinting at his fertility and evolutionary fitness, they said at a conference in Chicago.

That may be why the first kiss is often the last - 'the kiss of death'."