Robert Sapolsky has a bone to pick with oxytocin, or rather the public’s perception of oxytocin. It is the love hormone, we’ve surely all read by now. It helps us bond to our parents, then to our lovers and later to our own children. An extra dose can increase empathy, goodwill, and understanding. But it’s not all sunshine and rainbows, here’s the catch: those warm fuzzy feelings are only generated for people you already favor. Oxytocin, represented more honestly, is the hormone of love and violence. Its effect in the presence of people you consider “others” is preemptive aggression, and less social cooperation. It creates distance as often as it bonds love, and we are hardwired for those social dichotomies.

Humans invent “Us” and “Them” groups wherever they look, whether it’s on the basis of sex, race, nationality, class, age, religion, hair color—there’s nothing we won’t discriminate against, and we do it within a twentieth of a second of seeing someone. Are they an “Us” or are they a “Them”? The flaw in this hardwired thinking reflex is also its silver lining: it is ridiculously easy to manipulate. A racial bias can be duped by something so simple as putting a cap with your favorite sports team’s logo on someone’s head, for example. You can overthrow your brain’s most primal reactions in this way but, as history shows, other people can also get in your head and manipulate the Us versus Them reflex to tragic and catastrophic results.

Robert Sapolsky is the author of Behave: The Biology of Humans at Our Best and Worst.

Robert Sapolsky: So when you look at us—us as humans, as apes, as primates, as mammals—when you look at some of the most appalling realms of our behavior, much of it has to do with the fact that social organisms are really, really hardwired to make a basic dichotomy about the social world, which is those organisms who count as Us’s and those who count as Thems.

And this is virtually universal among humans and this is virtually universal among all sorts of social primates that have aspects of social structures built around separate social groupings. Us’s and Thems: we turn the world into Us’s and Thems and we don’t like the Thems very much and are often really awful to them. And the Us’s, we exaggerate how wonderful and how generous and how affiliative and how just like siblings they are to us. We divide the world into Us and Them.

And one of the greatest ways of seeing just biologically how real this fault line is, is there’s this hormone oxytocin. Oxytocin is officially the coolest, grooviest hormone on earth, because what everybody knows is it enhances mother-infant bonding and it enhances pair bonding in couples. And it makes you more trusting and empathic and emotionally expressive and better at reading expressions and more charitable. And it’s obvious that if you just, like, spritzed oxytocin up everyone’s noses on this planet it would be the Garden of Eden the next day.

Oxytocin promotes prosocial behavior. Until people look closely. And it turns out oxytocin does all those wondrous things only for people who you think of as an “Us”, as an in-group member. It improves in-group favoritism, in-group parochialism.

What does it do to individuals who you consider a Them? It makes you crappier to them, more preemptively aggressive, less cooperative in an economic game. What oxytocin does is enhance this Us/Them divide. So that, along with other findings—the classic lines of Us versus Them along the lines of race, of sex, of age, of socioeconomic class: your brain processes these Us/Them differences on the scale of milliseconds, a twentieth of a second, your brain is already responding differently to an Us versus Them.

Okay, so collectively this is depressing as hell. Oh my god, we are hardwired to inevitably be awful to Thems, and Thems along all sorts of disturbing lines of: "Oh, if only we could overcome these Us and Them dichotomies! Oh no, are we hardwired to divide the world along lines of race and ethnicity and nationality and all those disturbing things?" And what becomes clear is, when you look closely is: it is virtually inevitable that we divide the world into Us’s and Thems and don’t like Thems very much and don’t treat them well.

But we are incredibly easily manipulated as to who counts as an Us and who counts as a Them. And those fault lines that we view as, “Oh my god, how ancient can you get?” that say, somebody of another race evokes limbic responses in us, commensurate with they are a Them, they respond, they motivate automatic responses—"Oh my god, is that just the basic fault line?"
And then you do something like have faces of the same race versus other race, and either they are or aren’t wearing a baseball cap with your favorite team’s logo on it, and you completely redefine who's an Us. Us is people who like the Yankees and Them are Red Sox fans. And suddenly you’re processing, within milliseconds, what damn baseball cap they have, and race is being completely ignored.

“Oh my god, we are inevitably hardwired to make really distressing Us/Them...” We’re manipulated within seconds as to who counts as an Us and a Them.

Good news with that: we can manipulate us out of some of our worst Us/Them dichotomies and re-categorize people. Bad news: we could be manipulated by all sorts of ideologues out there as to deciding that people who seem just like us "really aren’t. They’re really so different that they count as a Them.”

Okay, so a fabulous study showing this, this double-edged quality to oxytocin, and this was a study done by a group in the Netherlands. And what they did was they took Dutch university student volunteers and they gave them a classic philosophy problem, the runaway trolley problem: “Is it okay to sacrifice one person to save five?” Runaway trolley: can you push this big, beefy guy onto the track who gets squashed by the trolley but that slows it down so that five people tied to the track don’t... Standard problem in philosophy, utilitarianism, ends justifies means—all of that. So you give people the scenario and people have varying opinions, and now you give them the scenario where the person you push onto the track has a name. And either it’s a standard name from the Netherlands, Dirk I think, this is like a meat-and-potatoes Netherlandish name. Or a name from either of two groups that evoke lots of xenophobic hostility among people from the Netherlands: someone with a typically German name—oh yeah, World War II, that’s right, that was a problem—or someone with a typically Muslim name.

So now they’re choosing whether to save five by pushing Dirk onto the track or Otto or Mahmoud and, in general, give them those names and there’s no difference in how people would rate them if they were anonymous.

Give people oxytocin, where they don’t know that they’ve gotten it—control group has just placebo spritzed up their nose—give people oxytocin and, kumbaya, you are far less likely to push Dirk onto the track, and you are now far more likely to push good old Otto or good old Mahmoud onto the rails there.

And you are more likely to sacrifice an out-group member to save five, and you are less likely to sacrifice an in-group member. All you’ve done there is exaggerate the Us/Them divide with that.