As you stare longingly into your lover's eyes this Valentine's Day, forget about love. Think instead about good, old-fashioned lust and you'll be much better-off for it. Just what's so great about having a one-track mind? Well, where to begin?
Activation of the sexual behavioural system (which is scientific shorthand for ‘lust') was designed by evolution to help us reproduce - its function, simply, is to get people into bed. And lust is exquisitely designed to do so - when horny we tend to see others as more attractive, pay good looking people more attention, and even read sexual intent into others' faces. All these mental shifts come with a narrowing of attention to the present and a focus on details, which makes sense as lust is about where to put what and in what order. And it's this last fact - that lust triggers local, detail-oriented processing - that underlies one of the most remarkable boons of this deadly sin - it makes you smarter.
Jens Forster and colleagues put participants in a lustful frame of mind by getting them think about having sex with a casual partner. When he later gave these sexed-brained participants a range of analytic problems to solve (of the "If A is less than B and B is greater than C, then is A less than C?" variety), they performed better than controls.
More good news: Lust can also make you more helpful. We all have some idea about what the other sex wants in a partner. There are some sex differences, of course, but both men and women want helpful, talented, kind, dependable types (they want other things too, but these traits will serve to make the points below). Now lust is so well designed to achieve its end (i.e., sex) that when we're aroused we tend to play up those very qualities that we know potential mates will find attractive. Men value helpfulness in women, so when women are turned on they (women) become more helpful. Women also want helpful men, but tend also to value traits like assertiveness, heroism and dominance, qualities which don't so easily meld with helpfulness. So what are we men to do? Don't worry, lust has worked it all out for us. When men are aroused, yes we are more helpful, but only when being helpful also communicates dominance, assertiveness and heroism (we'll happily distract a grizzly bear that's attacking a stranger, research suggests).
Perhaps the most fascinating thing about this deadly sin is that it may be responsible for much of what is interesting about human nature, from art and music, to theatre, language, and even virtue. For evolutionary psychologist, Geoffrey Miller, such attributes are human ornaments and can be thought of much like the peacock's tail. Peacocks' tails are advertisements in the sexual marketplace - they say ‘have sex with me, I have such good genes that I can manage this ridiculously large tail and still avoid predators.' And because peahens lust after big, fancy tails, sexual selection pressures drive the evolution of fancier and fancier ornamentation.
Miller thinks that the same thing might be happening with such human ornaments as creativity and even virtue. At first glance creativity doesn't seem to bring much to the fitness table in terms of natural selection - it doesn't really help us survive. (Indeed, I'd bet that reciting your amateurish poetry to an advancing predator would actually decrease your fitness). But, if creativity is valued by the opposite sex, it might have evolved via sexual selection. Creativity, like the peacock's tail, may be a signal of good genes, one that is hard to fake and sexually attractive. And honesty, kindness and empathy, according to Miller, may be much the same - we are just that bit more honest, kind, and empathic because such traits are more likely to turn on potential mates. Of course, the sexual selection account of virtue is one among many, but an intriguing one nevertheless and one a little too tempting to pass up in the face of moralistic prudery.
All told then, lust doesn't look so bad to me. So forget about love this Valentine's Day and raise a glass instead to everyone's favourite deadly sin.