In recent years a number of studies have reached the same thorny conclusion about human cognition: when encountering a person for the first time, our brains automatically make note of the individual's race. But new research indicates that this is not necessarily the case. Findings reported today in the Proceedings of the National Academy of Sciences indicate that even brief exposure to an alternative social world can markedly diminish the extent to which people categorize others by race. The results suggest that racism may be an erasable by-product of cognitive adaptations that evolved to detect coalitions and alliances.

Importantly, the same studies that seemed to suggest that humans have hardwired racist tendencies also indicated that people view each other in terms of sex and age. Yet whereas natural selection could conceivably favor automatic categorization according to those two factors, exactly how our ancestors might have benefited from encoding race is difficult to imagine. "Ancestral hunter gatherers traveled primarily by foot and, consequently, residential moves of greater than 40 miles would have been rare," note study authors Robert Kurzban, John Tooby and Leda Cosmides of the University of California at Santa Barbara. Encounters with members of different races were thus uncommon.

But the ability to assess allianceswhich the brain might in some cases link to appearanceswould have served early humans well, the researchers propose. To test that hypothesis, they showed test subjects members of two racially integrated rival basketball teams having an argument and subsequently asked a series of tricky questions about who said what. An analysis of the errors the study participants made showed that rather than mixing up members of the same raceas would be expected if they were categorizing by racethe subjects mixed up members of the same team.

"Our subjects had experienced a lifetime in which ethnicity (including race) was an ecologically valid predictor of people's social alliances and coalitional affiliations. Yet less than [four minutes] of exposure to an alternative social world in which race was irrelevant to the prevailing system of alliances caused a dramatic decrease in the extent to which they categorized others by race," the authors write. "If the same processes govern categorization outside the laboratory," they conclude, "then the prospects for reducing or even eliminating the widespread tendency to categorize persons by race may be very good indeed."