The love-hate hormone, ingroup/outgroup wars, and the power of culture

Ed Yong, who among other things is an oxytocin-news watchdog of late, highlights yet another study showing that oxytocin, sometimes typecast as the “love hormone,” carries a dark side. In case, the study, by Carsten de Dreu at the University of Amsterdam, shows that oxytocin can increase a feeling of bias toward people who are in an “outgroup” — that is, those who are perceived as different from a group we heavily identify with.

Despite its misleading labels, oxytocin has a dark side. Just two months ago, Jennifer Bartz showed that it can make people remember their mothers as less caring and more distant if they themselves are anxious about social relationships. Carolyn H. Declerck found that oxytocin makes people more cooperative in a social game, if they had met their partner beforehand. If they played with an anonymous partner who they knew nothing about, oxytocin actually made them less cooperative. “Oxytocin does not unconditionally support trust,” she says.

Now, Carsten de Dreu from the University of Amsterdam has found that sniffs of oxytocin make us more biased towards peers from our own ethnic or cultural group, versus those from other groups. Bartz commends the new study, saying, “Along with other recent reports, [the new study] suggests that although oxytocin clearly plays a role in prosociality and empathy, the way it does this is more nuanced than previously thought. This is not entirely surprising given the complexity of human relations.”

The study took 280 Dutch men, exposed them to three puffs of oxytocin nose-spray, and then, as Yong describes in a bit more detail, tested in several ways the Dutch men’s attitudes toward German, Arab, or other Dutch men. They found that the hormone increased the extent to which Dutch men thought poorly of German or Arab men and decreased the extent to which they thought me of those groups shared common emotions with them. Finally, they showed oxytocin increased the difference in how these Dutch men handled the so-called trolley problem — in which you’re faced with the prospect of sacrificing one person to save others — depending on whether the person to be sacrificed was in-group or out:

[De Dreu] presented [the Dutch] volunteers with a famous series of moral dilemmas. For example, a runaway rail trolley is hurtling towards five people who are about to be killed unless you flip a switch that diverts the trolley into the path of just one person. All of the dilemmas took the same form – you weigh the lives of one person against a group. And in all the cases, the lone person had either a Dutch, German or Arab name, while the group were nameless.

After a sniff of placebo, the Dutch volunteers were just as likely to sacrifice the single person, no matter what name they had. But after sniffing oxytocin, they were far less likely to sacrifice the Dutch loners than the German and Arab ones.

This last experiment clearly shows a trend that applied to the whole study: oxytocin boosted favouritism for people who belong to the same group. Only very rarely did it increase negative feelings towards people outside it. For example, in the moral dilemmas, oxytocin made the volunteers less likely to sacrifice members of their own group, but not more likely to sacrifice outsiders.

As Yong notes, oxytocin does not create this sense of in-group/outgroup difference; it merely increases it. The effect can be troubling to contemplate:

This sort of favouritism makes a degree of evolutionary sense. It could bolster trust and cooperation within a community, such that groups whose members stuck together more would out-compete those that did not. If that’s the case, you would expect the brain to have some way of sustaining racial biases and oxytocin could help with that.

It’s a clever, nicely conceived study and another solid, intelligent write-up by Yong. I’d add an important observation: This study highlights something vital to keep in mind when considering the effects of these hormones, and also of related polymorphisms that sometimes appear to influence their levels of activity: Though the mechanisms and traits these hormones and genes produce can seem quite specific and “hard-wired,” their actual expression — the behaviors, actions, and responses they help generate — usually depends heavily on context.

This really just points out the difference between trait and behavior. Traits, in the evolutionary sense, are general and foundational; behaviors are specific, and generally shaped by context. In this study, for instance, the trait was in-group/outgroup sensitivity, while the behavior — the expression of the trait in the study — was an apparent prejudice toward German and Arab men.

Here as in other arenas and traits, culture heavily shapes the context in which these traits are expressed. In the case of in-groups and out-groups, for instance, culture can and usually does define who’s in and who’s out. It can readily move us beyond obvious group markers such as  skin color or nationality to focus instead on shared values or practices, such as language. This is why, to cite a simple example, two strangers who favor the sports team might more readily identify each other as part of the same in-group even though they are of different ethnic, racial, or even national heritages. Similarly, another recent study, if I remember correctly, found that children paid more attention to similarity of speech than they did differences in race.

This offers a lesson not just in evolution — in what genes and traits are, as opposed to behaviors — but in civics. When it comes to in- and out-groups, we can, as individuals and as cultures, choose how to define our groups. We can stress differences that are arbitrary and seek to divide, or we can stress commonalities and seek to include, so that our larger culture and society are more healthy. We can downplay differences such as race, religion, sexual orientation, or political persuasion and focus instead on more cental values, such as regard for civility, fairness, tolerance, intellectual honesty, and diversity of opinion.

Some of our basic human traits may be deeply rooted. But our behaviors and actions rise from how current context shapes those traits. And as we’ve seen a bit too vividly lately in my home country, exploiting and fanning our fears of outgroups in an arbitrary, divisive manner, one meant to bring out our prejudices, does not bring out our best. We can do better.

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