The whole post is worth reading.To begin with, race is not a technical term in biology—it is used loosely for any differentiated subdivision of a species. For example, there is a fruit fly in Wisconsin that feeds on hawthorn and apple, and the flies that feed on the different trees are somewhat different, and so people refer to the “hawthorn race” and the “apple race”. Often, as in fact is true in this case, the term “race” is used because people aren’t quite sure exactly how different the forms are from one another.In zoology, the term “geographic race” does have a well-defined meaning. It means that if you look at an individual of a species, you can tell where it is from, or conversely, that if you tell me where the individual is from, I can tell you what it looks like. For example, there’s a species of lizard in Jamaica that if you brought one back and showed it to me, I could tell you whether it’s from the vicinity of Kingston, or Montego Bay, or Negril, etc. Lizards from these various places are members of the same species because they interbreed with one another where they are in geographic proximity; they are geographic races because I can tell where they are from by looking at them. Geographic races, if they are given taxonomic names, are called subspecies.With regard to humans, most of the genetic variability is within populations, not between local populations or races. This was pointed out by Dick Lewontin in 1972 (Dick, of course, was Jerry’s dissertation adviser, and my de jure adviser). However, just because most of the variation is within populations doesn’t mean you can’t tell where someone is from by looking at him. The geneticist Tony Edwards later called the mistaken notion that a majority of variation being within populations precludes identification of population membership “Lewontin’s Fallacy”.As a former student of Lewontin’s, I’m not especially fond of Edwards’ choice of term, but nonetheless Edwards is entirely correct. It is of crucial importance to note that the scientific questions asked by Lewontin and Edwards were different. Lewontin asked “What proportion of genetic variation (in the analysis of variance sense) in humans is within and among populations?” The answer is that roughly 85% is within populations, the rest among local populations and races. That is the answer Lewontin gave in 1972, and it is entirely correct, confirmed by much more molecular data since that time. Edwards asked “Can individual humans be assigned to races from genetic data?”, or, alternatively, “Can human races be diagnosed (in the taxonomic sense of subspecies)?” The answer is yes, they can.