Oxytocin is enjoying a huge vogue. It’s been christened the “love hormone” and the “cuddle chemical”, due to its supposed effect in increasing human bonding. One whiff of it can make a person more trusting, empathetic, generous and cooperative.
Sold on the Internet in a formulation called “Liquid Trust,” the peptide hormone is marketed as a romance enhancer. Australian therapists are trying it alongside counseling for couples with ailing marriages. And police and military forces reportedly are interested in its potential to elicit cooperation from crime suspects or enemy agents.
With around 40 clinical trials under way using oxytocin to treat conditions such as autism and schizophrenia, there is a lot of optimism that the hormone could help people by boosting trust and reducing social anxiety.
But it’s emerging that this wonder hormone is not nearly as simple and friendly as people have tried to portray it.
True, there have been lots of positive studies. Thousands in fact, including the now-famous study that showed oxytocin helps to cement the bonds between prairie voles, which mate for life. It also triggers the motherly behaviour that sheep show towards their newborn lambs and is also released in humans during childbirth, strengthening the attachment between mother and baby.
Its reputation grew after a groundbreaking experiment published in 2005, in which Heinrichs and colleagues asked volunteers to play a game in which they could invest money with an anonymous trustee, who was not guaranteed to be honest. The team found that participants who had sniffed oxytocin via a nasal spray beforehand invested more money than those given a placebo (Nature, vol 435, p 673).
Many subsequent studies, involving groups of volunteers being given either oxytocin or a placebo and then carrying out a task to test their social skills, showed that people donate more money to charity, become better at reading emotions on other people’s faces, communicate more constructively during arguments, and perceive others to be more trustworthy, attractive and approachable. Together, the results fuelled the view that oxytocin universally enhances the positive aspects of our social nature.
But alert scientists have noticed major cracks in the image. It’s not that previous results were not “true”, as such. But it emerges that oxytocin is context dependent. If you are a friendly, sociable person, you’ll be more so with oxytocin.
But if you are socially inept, judgmental, jealous, anxious or inclined to sneer at others, it may make you worse! It may be the last thing to give autistic kids!
Simone Shamay-Tsoory at the University of Haifa, Israel, showed that as well as promoting trust and generosity, oxytocin can heighten feelings of envy and schadenfreude (Journal of Biological Psychiatry, vol 66, p 864).
Schadenfreude is the posh word for that nasty human trait of enjoying other peoples’ dismay. They get upset; you laugh (behind their backs, of course).
When volunteers played a gambling game, those who inhaled the hormone gloated more when they beat other players. They also felt sharper stabs of jealousy when the tables were turned. Clearly, oxytocin can produce antisocial as well as social behaviour.
Moreover, Jennifer Bartz from the Mount Sinai School of Medicine, New York, found that it only improves people’s ability to read emotions, if they are not very socially adept to begin with (Psychological Science, vol 21, p 1426).
Bartz and her team also showed oxytocin actually reduces trust and cooperation in people who are particularly anxious or sensitive to rejection (Social Cognitive and Affective Neuroscience, vol 6, p 556).
It also gives people fonder recollections of their mothers, but only if they are secure in their personal relationships. If they are socially anxious, oxytocin makes them remember their mums as being less caring and more distant (Proceedings of the National Academy of Sciences, vol 107, p 21371).
Fathers too, I expect. I wonder if that is behind false memory syndrome and women denouncing their fathers, claiming they had been abused (women who were severely dysfunctional to start with).
There is a cultural context too. Carsten de Dreu at the University of Amsterdam in the Netherlands discovered that oxytocin-sniffers show more trust and cooperation towards their compatriots, but not people of other nationalities (Science, vol 328, p 1408). De Dreu says that oxytocin promotes a “tend and defend” response, one that drives people to care for those in their social circles and protect them from outside dangers. “It’s what we call the mama-bear effect,” he says. So, rather than promoting blanket goodwill, oxytocin strengthens biases.
Far from being simple, oxytocin is emerging as a very complex substance. It’s mediated through a protein found throughout the nervous and reproductive systems, which is coded by the so-called OXTR gene,
A change in one of the gene’s DNA letters, from A to G, makes people more socially sensitive. G-carriers tend to be more empathetic and less lonely. They are also more likely to turn to their friends in times of trouble, but only if they live in a culture where it is customary to seek companionship when distressed.
There were signs of these subtleties from the start. Jennifer Bartz has recently pointed out that in almost half the existing studies, oxytocin held sway only over certain individuals or in particular circumstances; it’s just that these nuances were overlooked in the general enthusiasm to find every possible good in this molecule (Trends in Cognitive Sciences, vol 15, p 301).
Now the tendency is shifting towards new directions, in which the dark side is more closely observed, since it clearly exists.
Perhaps we should not be surprised that the oxytocin story has got more complicated. It promotes lactation and uterine contractions; sexual activity, penile erection and ejaculation; as well as social bonding and other factors. The hormone is found in everything from octopuses to sheep, and its evolutionary roots stretch back half a billion years.
We are come lately to the party and its effects on the human brain are bound to be varied and somewhat extraordinary. Maybe there is a bit of the primitive in all of us?