Are Humans Hard-Wired for Racial Prejudice?

And here's the most heartening news: These brain responses can be fairly easily overridden. Chad Forbes at the  University of Delaware demonstrated that if whites viewed a black face while hearing loud rap music, the amygdaloid response got even bigger. But put that same face over death-metal music — associated with negative white stereotypes — and you don't get the same amygdala reaction.

Moreover, the brain's response to race can be overridden by re-categorizing people. As reported by Robert Kurzban at the  University of Pennsylvania, subjects shown a film clip of a mixed-race crowd of people tended to unconsciously categorize people in the crowd by race. But if people in that crowd were wearing one of two different sports jerseys, subjects categorized them by team affiliation instead of by race. In other words, if the brain evolved to make automatic racial distinctions, it evolved even more strongly to differentiate between Dodgers fans and Giants fans.

Finally, work by Susan Fiske at Princeton found something else that can override the amygdala response to another race. Subjects were asked to decide whether people in the pictures they were shown would like a particular vegetable. In other words, they were asked to imagine the tastes of the people, to think about what they'd buy in a market, and to imagine them relishing a favorite vegetable over dinner. In that exercise, even if the face a subject saw was of another race, the amygdala wasn't activated.

In other words, simply thinking about someone as a person rather than a category makes that supposedly brain-based automatic xenophobia toward other races evaporate in an instant. Maybe there's hope for us as a species after all.

Robert M. Sapolsky is a professor of neuroscience at  Stanford University and the author of "A Primate's Memoir," among other books. He is a contributing writer to Opinion.