Love and lust are, like hunger and thirst, hormone-induced states that our brains reward us for lest we forget to have sex, eat and drink. Love, feeling madly in love, is different from hunger or fear, though:

[T]he brain areas active in love are different from the areas activated in other emotional states, such as fear and anger. Parts of the brain that are love-bitten include the one responsible for gut feelings, and the ones which generate the euphoria induced by drugs such as cocaine. So the brains of people deeply in love do not look like those of people experiencing strong emotions, but instead like those of people snorting coke.

Prairie voles – and presumably humans – have a lot of variation in their vasopressin receptors though. That’s why some love more constantly than others.

Oh, you might be able to supress love using drugs like Prozac, because crazy-in-love-with-you is characterised by low levels of serotonin, but, the experts say, you’d only stand a chance of fighting love in its early stages, or perhaps when healing after a bad breakup. Love is a more powerful drive than hunger.

Soon we’ll have DNA tests along with the prenup.