ESSAY

In a recent issue of Nature, the neuroscientist Larry Young offers a grand unified theory of love. After analyzing the brain chemistry of mammalian pair bonding, Dr.Young predicts that it won’t be long before an unscrupulous suitor could sneak a pharmaceutical love potion into your drink.

The good news is that we might reverse-engineer an anti-love potion, a vaccine preventing you from making an infatuated ass of yourself.

This is what humans have sought ever since Odysseus ordered his crew to tie him to the mast while sailing past the Sirens. It was clear that love was a dangerous disease.

Dr.Young conducted research with prairie voles at the Yerkes National Primate Research Center at Emory University in Atlanta. These mouselike creatures are among the small minority of mammals? less than 5 percent? who share humans’propensity for monogamy. When a female prairie vole’s brain is artificially infused with oxytocin, a hormone that produces some of the same neural rewards as nicotine and cocaine, she’ll quickly become attached to the nearest male. A related hormone, vasopressin, creates urges for bonding and nesting when it is injected in male voles (or naturally activated by sex).

After Dr.Young found that male voles with a genetically limited vasopressin response were less likely to find mates, Swedish researchers reported that men with a similar genetic tendency were less likely to get married. In his Nature essay, Dr.Young speculates that human love is set off by a“biochemical chain of events”that originally evolved in ancient brain circuits involving mother-child bonding, which is stimulated in mammals by the release of oxytocin during labor, delivery and nursing.

Dr.Young noted that sexual foreplay and intercourse stimulate the same parts of a woman’s body that are involved in giving birth and nursing. This hormonal hypothesis would help explain a couple of differences between humans and less monogamous mammals: females’ desire to have sex even when they are not fertile, and males’ erotic fascination with breasts. More frequent sex and more attention to breasts, Dr. Young said, could help build long-term bonds through a“cocktail of ancient neuropeptides,”like the oxytocin released during foreplay or orgasm.

Researchers have achieved similar results by squirting oxytocin into people’s nostrils. It seems to enhance feelings of trust and empathy. Dr.Young said there could be drugs that increase people’s urge to fall in love.

But a love vaccine that can prevent infatuation seems simpler and more practical.“If we give an oxytocin blocker to female voles, they become like 95 percent of other mammal species,”Dr.Young said.“They will not bond no matter how many times they mate with a male or how hard he tries to bond. They mate, it feels really good and they move on if another male comes along. If love is similarly biochemically based, you should in theory be able to suppress it in a similar way.”


JOHN TIERNEY