In the Western world, Valentine’s Day expressions of affection are closely linked to mouth-to-mouth kisses. I remember feeling envious years ago when a colleague found a card in his pigeon-hole ...

For humans, kissing holds major cultural cachet, accompanying confessions of romantic love, religious rituals of reverence and even betrayals, à la The Godfather Part II’s “kiss of death.” New ...

If you think about it, kissing is really weird. You press your sensitive, nerve-filled facial muscles against another person’s. You exchange a cocktail of saliva, exposing yourself to millions of ...