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. Whereas gender (sex) has been shown to have a biological set of criteria, despite some gray areas, such that almost every individual human being can be said- after a complete medical evaluation including examination of chromosomes and sequencing of genotype, to be a man (boy) or woman (girl), there are no distinct set of biological criteria that can be used to determine the race of an individual in an unambiguous sense- unless race is said to be equivalent to skin color or to superficial appearance. A hundred years ago, and before, many of the greatest biologists predicted that this would not be the case. Instead, they assumed that there were definite qualitative biological differences inherent in members of the races of mankind, such that each was distinctive.

The term, "race" in biology has several meanings- some are used only infrequently or in certain contexts. In the 19th century, and before, the word "race" was often used in biology as a synonym for a kind or kindred of creature or plant, and the term race was generally applied to all manner of living things to describe species, and, alternatively, to describe the set of relatives or descendants of a designated individual. For example, the full title of one of Charles Darwin's books, published in 1859, is "On the Origin of Species By Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life."

The word, "race" has been applied to people in a different, non-biologic way, as a kind, or sort, of person- such as "the race of women" or the "race of gamblers", sometimes in a poetic or humorous way. In fact, the word race is popularly used to refer to all mankind, or Homo sapiens, as the human race, to distinguish us from other kinds (races) of living things. Most notably, race, in both biology and popular usage, is used to designate categories of human ethnic groups. The history of the word "race" used as a designation for ethnic groups in biology has few poetic or humorous associations. Instead, that history is strongly figured in the support of a number of social, health science, and military undertakings that have ranged from Negro slavery to Eugenics to The Holocaust, and Apartheid, and been generally accepted to be among the most shameful accomplishments of the human race. Particularly since the aftermath of the Holocaust , when the result of the biological thinking that led the Nazi regime to rationalize genocide became clearly understood, there has been a great reluctance within anthropology, medicine, and other fields of human biology to approach basic research according to racial ideation. Today, it is difficult to find chapters in current textbooks in any of these fields entitled "Race", for example. When such articles or chapters are encountered, they more often discuss race as a specific kindred, rather than the "races of man", or they discuss cultural characteristics, like "Use of surgical services by blacks in Chicago". That was not true in texts of these disciplines before World War II.

This is a remarkable testament to the impact of social history on biology, because, during this same post-WW II era, the power of molecular biology and, most particularly, molecular genetics, has been a driving force in biological research and lends itself to the analysis of inherited features and the biology of kindreds. In one meaning of the word "race", that is not used technically as a biological term, race refers to all of the descendents of an individual (The race of Abraham, the race of King Henry), and in that sense only much of modern human genetics has focused on the study of race. Even though these studies have not been generally aimed at comparing the classic races of mankind that were and are popularly acknowleged: Caucasian, Negroid, Mongoloid, there has been so much analysis of kindreds that fall into these groups that it is possible to discuss the findings in terms of that meaning of race. What has been found out so far, is that there are no qualitative biological differences that correspond to these groups and currently, in human biology , including health science and anthropology, the term race is not held to have any absolute biological meaning outside of explicitly defined kinship groups. Of course, there are biological studies of "whites" and "blacks", for example, in health sciences; but these are descriptive studies of response to medication, or prevalence of disease, in socially defined groups - often self-defined, and they have the same kind of significance as studies of urban populations, or residents of certain geographic areas; in other words the groups are defined by non-biological, criteria and then studied for biological characteristics.

Currently, in plants and animals, the word "race" is not ordinarily used as primary designation of type, although it is still used properly as a synonym for "kind" in biology. Instead, when it comes to groups of plants, animals, or microorganisms, that are related by inheritance and share characteristics; the words subspecies, breed, variety, and strains are most frequently and properly used. When discussing human beings, these words (subspecies etc.) have never had any common usage in biology, anthropology, or medicine, and instead the word "race" has been used preferentially.

Historically, there have been biological definitions of races. By the nineteenth century, western biologists separated 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. In fact, some biologists of that era argued that certain races of human beings were not the same species as other races. 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 other kinds of genetic markers. Some of these markers are particular sequences of nucleotides in DNA that are different in different people, and inherited by their offspring. 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 eugeneticists, 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 populations 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.

Mitochondrial DNA

Mitochondrial DNA is different that the DNA in the nucleus of cells. Unlike that nuclear DNA, the Mitochonrial DNA does not undergo recombination between sperm and egg, but is inherited intact from the mother. Mitichondria contain the cytochrome system for oxidative phosphorylation in metabolism, and mitochondrial DNA can be assayed by probing with sequences that are known to be contained in the genes that code for cytochromes, such as cytochrome b.

History of Biology: Race and Biology

Current thinking:Race and Biology

The current thinking about race and biology is not simply a reaction to political change, but also reflects a different concept of the importance of breeds and subspecies in taxonomy. In so far as the traditional notions of race correlated with ideas of species and subspecies in biology, changes in the views towards human races parallel some of the changes in views towards the subclassification of animals.

As refined techniques in genetics have been used to examine specimens of different breeds, the variations that are found to be distinctive generally have to do with one of two findings. Either the gene is one that is known to produce a certain phenotypic trait, and is present in animals of the breed who exibit the trait, or the gene haplotype or a genetic polymorphism is found in the breed and indicates the ancestry of the breed. For example, Chunky broiler chickens can be distinguished from White Leghorn, Fayoumi, and Black Minorca chickens by two polymorphisms in the cytochrome b region.