The Love Drug’s Dark Side

Everyone loves oxytocin, the hormone and neurotransmitter that functions as the body’s internal “love drug.” It has a reputation as the warmest, fuzziest chemical around. As I’ve written about earlier, oxytocin can moderate feelings of fear in social settings. But it does much more than that. Apart from a rather extensive list of functions in sexual reproduction, childbirth, and breastfeeding, oxytocin affects how mammals behave towards one another. In one famous experiment, for instance, subjects were found to behave more empathically after inhaling a dose of oxytocin-laced nasal drops.

But not all of oxytocin’s effects are so delightful. Experiments with rats have shown that increased levels of oxytocin can lead, in certain circumstances, to heightened aggression. And a recent experiment carried out at the University of Haifa in Israel has found some not-so-pleasant effects in humans as well. Subjects were given doses of nasal spray that contained either oxytocin or a placebo, and asked to play a computer game against a fellow test-subject. Actually, for the sake of experimental consistency, there was no other player — the subjects were playing against a computer. The interesting result was that subjects who had taken oxytocin gloated more when they won, and were more envious when they lost, than controls were.

It seems, explains researcher Simone Shamay-Tsoory, that oxytocin somehow helps to engage a person’s social drive, for better or for worse. “When the person’s association is positive, oxytocin bolsters pro-social behaviors; when the association is negative, the hormone increases negative sentiments,” she says.