-Submitted by David Drumm (Nal), Guest Blogger
Leading scientists, including evolutionary biologists, geneticists, and anthropologists, can’t agree on the existence of human races, and it’s a fascinating discussion. The human desire to categorize everything is often puzzling, sometimes amusing, and sometimes enlightening. Race is one of the results of our categorization compulsion applied to ourselves.
To define race, Jerry Coyne turns to our experience with animals: “races of animals (also called “subspecies” or “ecotypes”) are morphologically distinguishable populations that live in allopatry (i.e. are geographically separated).” While humans from Norway and from sub-Saharan Africa are certainly “morphologically distinguishable,” for example in skin pigment, eye and hair color, and nose shape, there is a continuous distribution on morphology between the geographic extremes.
As can be seen from the graph above, from Human Races: A Genetic and Evolutionary Perspective (pdf) by Alan R. Templeton, genetic distance and geographical distance form a cline and not discrete changes that would indicate races. It is possible to cherry-pick the genetic information from geographically distance populations and produce a graph that clusters those populations and claim it manifests discrete races. However, this ignores the in-between genetic information that smears the discrete clustering into a homogeneous mix.
Hence, human races do not exist under the traditional concept of a subspecies as being a geographically circumscribed population showing sharp genetic differentiation. A more modem definition of race is that of a distinct evolutionary lineage within a species. The genetic evidence strongly rejects the existence of distinct evolutionary lineages within humans.
From Genetics, Evolution, and Man, L.L. Cavalli-Sforza wrote:
The criteria for the definition of races – based on geographic distribution and various features of the body – yield classifications similar to those obtained using genetic markers. Use of genetic markers also shows very clearly that there are no “pure” races. Races are, in fact, generally very far from pure and, as a result, any classification of races is arbitrary, imperfect, and difficult. Yet anyone can see that there are certain relatively clear differences between a typical Caucasoid and a typical Mongoloid or a typical Negroid.
In the landmark paper The apportionment of human diversity, R. C. Lewontin found that 85% of all human genetic variation is found between individuals within a nation or tribe and only 6% between the races. Since obvious phenotypical differences exist between human populations, that 6% variation can have significant effects. Not all genetic variation is created equal.