Race (biology)

See race for a more general treatment of the concept of human races, and see subspecies for the concept of "race" as applied to all species; the following article concerns how biologists have approached human races.

Races of humans have been delineated by many cultures over human history. After the fact, once these racial groups had already been described on a social and cultural basis, biologists and physicians have studied them from a genetic and medical perspective.

Historically, there have been definitions of races that assumed that some racial groups were superior, or more highly evolved, or at least held major biological differences from other racial groups. By the nineteenth century, western biologists grouped human beings into various racial classifications under the assumption that there were distinct biological differences between them, similar to the differences between species, or subspecies. More recently, molecular genetic analysis has shown that there do not appear to be measureable genetic differences according to these classic racial groups. However, when populations of people are related, then they do tend to share certain forms of genes and genetic markers. Some of these markers are particular sequences of nucleotides in DNA that are different in different people, and inherited. These sequences, which include microsatellite DNA, are often so highly variable that they are therefore especially useful for looking for inherited relationships, even though these distinctively variable sequences do not code for proteins, as genes do. Genetic polymorphisms have been used to construct theoretical family trees of man, and to plot historical migrations according to where populations with shared polymorphisms appear. However useful these genetic markers are, they have not revealed the kinds of qualitative differences that were once assumed to be inherent features of human races, tribes, and ethnic groups by eugenecists, sociologists and sociobiological theorists of the past.

Genetic markers of populations

Since the development of PCR and other rapid, powerful DNA chemistry laboratory techniques, there have been multiple investigations of how the frequency of certain sequences vary in different populations. These different forms of DNA are called polymorphisms and, since they vary on an inherited basis, polymorphisms can be useful for tracing the ancestries of populations. For example, in 1966 the Gm ab3st gene was shown to be common in Mongoloid people, including Asians and Native Americans. Since then, four different varieties of the gene, Gm haplotypes, have been described: Gm ag, axg, ab3st, and afb1b3. When individuals have these GM haplotypes, they fall into one of two patterns- " the first is a southern group characterized by a remarkably high frequency of Gm afb1b3 and a low frequency of Gm ag, and the second, a northern group characterized by a high frequency of both Gm ag and Gm ab3st but an extremely low frequency of Gm afb1b3." (Hideo Matsumoto. Characteristics of Mongoloid and neighboring populations based on the genetic markers of human immunoglobulins. Human genetics. Volume 80, Number 3 / November, 1988 207-218). By studying the frequencies of these genes in poulations throughout the world, researchers have concluded that the Japanese race belongs to northern Mongoloids and that the origin of the Japanese race was in Siberia, and most likely in the Baikal area of the Soviet Union. This kind of genetic marker research is fairly typical of racial studies in current biology. In other words, it is possible to make correlations in the historical migration of peoples and gene markers.