Speaking about black and white, what about racism? Why is it still such a hot issue in our society despite decades of progress?

First, let's define "race." Many definitions of race have been used in the last few hundred years in the Western world, and there remains some confusion about what is meant by the word. According to one definition, a race is a group of individuals who share some common physical characteristics that distinguish them from other individuals in the species. Although members of different races are members of the same species and can breed together, some kind of separationÑusually geographicÑhas prevented them from doing so for some period. During that period, the distinctive differences between the groups emerged. This definition implies that differences between groups are based in biological differences.

Many of the most extreme racist doctrines of the past have been based on the assumption of biological differences between groups. Controversy over these issues, such as whether genetic differences between groups are the cause of group differences on IQ test scores, still swirls through academic and public debates.

Scientists generally believe that this concept of raceÑas based on biological differencesÑdoes not fit the case of human groups. Biological distinctions are quite minor compared with the commonalties at the biological level. Of the variation in genetic material among humans, only a small part of the variation is accounted for by "racial" group membership. The majority of the variation occurs within groups. Differences in skin pigmentation, facial features, and so on may seem visually significant, but such physical differences between groups represent only a small proportion of human genetic variation.

Instead, "races" are groups with primarily different histories, cultures, and social organizations. The notion of "race," with the underlying assumption of biological differences, is probably not the best way to categorize different groups. But the use of the terms "race" and "racial group" is so common that it is hard to avoid.