Science-- there's something for everyone

Monday, April 4, 2011

The evolutionary roots of prejudice

Humans automatically classify other humans as members of the ‘ingroup’ (belonging to the same clan, religion, race, caste or nationality) or members of ‘outgroups’ (outsiders, who are viewed with suspicion). Why do we divide people up in this manner? According to research led by Laurie Santos from Yale University, we evolved that way. Santos and her colleagues based their conclusion on the fact that rhesus macaques (Macaca mulatta), monkeys with which we shared a common ancestor 25 million years ago, display the same prejudices.

The scientists made use of the stare test I’ve written about before. Like humans, macaques will stare longer at unusual or threatening images than at mundane, peaceful ones. When shown pictures of other macaques, the monkeys started longer at members of other troops than at monkeys within their own groups. It isn’t too surprising that monkeys would stare longer at unfamiliar faces. I can’t say the same about the next experiment though.

This time, the researchers showed the monkeys paired photos including a monkey’s face and an object that monkeys either desire or abhor. For example, a pair might include a face and a piece of ripe fruit, or a face and a spider. This time, the monkeys stared the longest at outgroup faces paired with good objects. In other words, if an outsider was associated with something bad, or a troop member was seen next to a nice item, that was considered normal. To see an outsider paired with something nice seemed a little weird to the monkeys.

Humans show the same kinds of proclivities for associating good things with ingroup members and bad things with outgroup members. Apparently, we come by that strategy naturally. You can test your own inherent prejudices about groups of people by taking an implicit attitude test.