The attire of competitors playing combat sports at the 2004 Olympic Games is the unlikely subject of a sparring session between biologists in Nature this week, as scientists argue whether the theories of evolutionary psychology can explain why teams wearing certain colors are more likely to win. In the red corner are scientists who argue there are evolutionary explanations for why red teams often win. In the blue corner, scientists say blue teams can win, too, and red and blue teams are likely more often victorious because white-wearing teams are easier to see, and therefore anticipate.

Previous research has suggested that the color of team uniforms can influence the players wearing them—for instance, players who wear black tend to be more aggressive. In May, 2005, Russell Hill and Robert Barton from Durham University, UK, took it a step further. They released an analysis of the results of combat sports --...