Names of different races and features in the world in biological term
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Abstract
Races may exist in humans in a cultural sense, but biological concepts of race are needed to access their reality in a non-species-specific manner and to see if cultural categories correspond to biological categories within humans. Modern biological concepts of race can be implemented objectively with molecular genetic data through hypothesis-testing. Genetic data sets are used to see if biological races exist in humans and in our closest evolutionary relative, the chimpanzee. Using the two most commonly used biological concepts of race, chimpanzees are indeed subdivided into races but humans are not. Adaptive traits, such as skin color, have frequently been used to define races in humans, but such adaptive traits reflect the underlying environmental factor to which they are adaptive and not overall genetic differentiation, and different adaptive traits define discordant groups. There are no objective criteria for choosing one adaptive trait over another to define race. As a consequence, adaptive traits do not define races in humans. Much of the recent scientific literature on human evolution portrays human populations as separate branches on an evolutionary tree. A tree-like structure among humans has been falsified whenever tested, so this practice is scientifically indefensible. It is also socially irresponsible as these pictorial representations of human evolution have more impact on the general public than nuanced phrases in the text of a scientific paper. Humans have much genetic diversity, but the vast majority of this diversity reflects individual uniqueness and not race.
Keywords: admixture, evolutionary lineage, gene flow, genetic differentiation, race, human evolution
The Biological Meaning of ‘Race’
Many human societies classify people into racial categories. These categories often have very real effects politically, socially, and economically. Even if race is culturally real, that does not mean that these societal racial categories are biologically meaningful. For example, individuals who classify themselves as “white” in Brazil are often considered “black” in the U.S.A., and many other countries use similar or identical racial terms in highly inconsistent fashions (Fish, 2002). This inconsistency is only reinforced when examined genetically. For example, Lao et al. (2010) assessed the geographical ancestry of self-declared “whites” and “blacks” in the United States by the use of a panel of geographically informative genetic markers. It is well known that the frequencies of alleles vary over geographical space in humans. Although the differences in allele frequencies are generally very modest for any one gene, it is possible with modern DNA technology to infer the geographical ancestry of individuals by scoring large numbers of genes. Using such geographically informative markers, self-identified “whites” from the United States are primarily of European ancestry, whereas U.S. “blacks” are primarily of African ancestry, with little overlap in the amount of African ancestry between self-classified U.S. “whites” and “blacks”. In contrast, Santos et al. (2009) did a similar genetic assessment of Brazilians who self-identified themselves as “whites”, “browns”, and “blacks” and found extensive overlap in the amount of African ancestry among all these “races”. Indeed, many Brazilian “whites” have more African ancestry than some U.S. “blacks”. Obviously, the culturally defined racial categories of “white” and “black” do not have the same genetic meanings in the United States and Brazil. The inconsistencies in the meaning of “race” across cultures and with genetic ancestry provide a compelling reason for a biological-based, culture-free definition of race. Another reason is that humans are the product of the same evolutionary processes that have led to all the other species on this planet.
The word “race” is not commonly used in the non-human biological literature. Evolutionary biologists have many words for subdivisions within a species (Templeton, 2006). At the lowest level are demes, local breeding populations. Demes have no connotation of being a major subdivision or type within a species. In human population genetics, even small ethnic groups or tribes are frequently subdivided into multiple demes, whereas “race” always refers to a much larger grouping. Another type of subdivision is “ecotype”, which refers to a group of individuals sharing one or more adaptations to a specific environment. Sometimes the defining environmental variable is widespread, so an ecotype can refer to a large geographical population. However, sometimes the environmental heterogeneity can exist on a small geographical scale. In such circumstances, a single local area with no significant genetic subdivision for almost all genes can contain more than one ecotype (e.g., Oberle & Schaal, 2011).