This topic is better covered at the Cleveland Museum of Natural History dinosaur mailing list. Essentially the idea is: you cannot subdivide humans like dogs. According to poster, Kyle Brudvik, humans have a large range of variation in one species, but don't make the mistake of seeing this variation as anything other than variation within a species. There is absolutely no reason to erect racial groups because where do you draw the line? How many people do you include in your groups? Only those who fit your presupposed criteria for inclusion? Besides, what are these mysterious racial characterisitics? They come from people's imaginations and are applied to humans, they are not the results of observations of any naturally defined populations.