Hating These Humans Is The Easiest Thing To Do...,

nautil.us |  Considerable evidence suggests that dividing the world into Us and Them is deeply hard-wired in our brains, with an ancient evolutionary legacy. For starters, we detect Us/Them differences with stunning speed. Stick someone in a “functional MRI”—a brain scanner that indicates activity in various brain regions under particular circumstances. Flash up pictures of faces for 50 milliseconds—a 20th of a second—barely at the level of detection. And remarkably, with even such minimal exposure, the brain processes faces of Thems differently than Us-es.

This has been studied extensively with the inflammatory Us/Them of race. Briefly flash up the face of someone of a different race (compared with a same-race face) and, on average, there is preferential activation of the amygdala, a brain region associated with fear, anxiety, and aggression. Moreover, other-race faces cause less activation than do same-race faces in the fusiform cortex, a region specializing in facial recognition; along with that comes less accuracy at remembering other-race faces. Watching a film of a hand being poked with a needle causes an “isomorphic reflex,” where the part of the motor cortex corresponding to your own hand activates, and your hand clenches—unless the hand is of another race, in which case less of this effect is produced.

The brain’s fault lines dividing Us from Them are also shown with the hormone oxytocin. It’s famed for its pro-social effects—oxytocin prompts people to be more trusting, cooperative, and generous. But, crucially, this is how oxytocin influences behavior toward members of your own group. When it comes to outgroup members, it does the opposite.

The automatic, unconscious nature of Us/Them-ing attests to its depth. This can be demonstrated with the fiendishly clever Implicit Association Test. Suppose you’re deeply prejudiced against trolls, consider them inferior to humans. To simplify, this can be revealed with the Implicit Association Test, where subjects look at pictures of humans or trolls, coupled with words with positive or negative connotations. The couplings can support the direction of your biases (e.g., a human face and the word “honest,” a troll face and the word “deceitful”), or can run counter to your biases. And people take slightly longer, a fraction of a second, to process discordant pairings. It’s automatic—you’re not fuming about clannish troll business practices or troll brutality in the Battle of Somewhere in 1523. You’re processing words and pictures, and your anti-troll bias makes you unconsciously pause, stopped by the dissonance linking troll with “lovely,” or human with “malodorous.”

We’re not alone in Us/Them-ing. It’s no news that other primates can make violent Us/Them distinctions; after all, chimps band together and systematically kill the males in a neighboring group. Recent work, adapting the Implicit Association Test to another species, suggests that even other primates have implicit negative associations with Others. Rhesus monkeys would look at pictures either of members of their own group or strangers, coupled with pictures of things with positive or negative connotations. And monkeys would look longer at pairings discordant with their biases (e.g., pictures of members of their own group with pictures of spiders). These monkeys don’t just fight neighbors over resources. They have negative associations about them—“Those guys are like yucky spiders, but us, us, we’re like luscious fruit.”

Thus, the strength of Us/Them-ing is shown by the: speed and minimal sensory stimuli required for the brain to process group differences; tendency to group according to arbitrary differences, and then imbue those differences with supposedly rational power; unconscious automaticity of such processes; and rudiments of it in other primates. As we’ll see now, we tend to think of Us, but not Thems, fairly straightforwardly.