They can't. That's because what we refer to as "races" in humans do not map onto genetically distinct lineages of humans. . . . Though the concept of biological race is not entirely un-useful when talking about humans (just as it is not un-useful when talking about bees and citrus plants), the way that it is commonly used bears no correspondence to its biological meaning, and is therefore useless as a biological concept for humans as it is currently used, because it bears no commonality with real biological distinctions.
Well, there are some genes that map onto "races". The Pima tribe of the southwestern US are at super high risk for diabetes, and that maps exactly and is thought to be genetic. Sickle cell anemia tracks with people with African ancestry. Hemochromatosis is much more frequent in people with northern European ancestry. Tay-Sachs disease is much more common in people with Ashkenazi Jewish ancestry. I just don't see any evidence that a specific phobia is carried in genes that track with where people's ancestors are from. The connections between genes & behaviors are difficult to make in the first place, and they seem to be lineage specific, like the separated identical twins who wind up being fire fighters, rather than race specific.
In contesting my point, you've actually made it for me. I recognize that the medical field still holds onto what is useful about recognizing humans with distinct historical lineages, and that's important, but the medical field simply doesn't use the word "race" to mean what it actually means in the other biological fields. It's a historical artifact, really, of medical nomenclature. It's the same in forensics.
The examples you give of genes that occur in high frequencies within particular human lineages are indeed due to their common ancestry. Lineages = as you say, where your ancestors are from. But these lineages don't map onto either the biological definition of race or our culturally dictated ones. Lineages are much smaller than biological races, which are roughly defined as relatively isolated breeding populations that share morphological characteristics at higher frequencies than are found in the species at large. You have to be able to look at something, and measure its morphological characteristics, and reliably sort it into its correct breeding population or "race." You can do it with races of bees, and with races of citrus. Some people put a number on how high the degree of breeding isolation has to be (or the genetic distance between races) as quantified by genetic distance markers (none of which are met by genetic distances among any major populations of humans). Individual lineages do indeed share genetic material. The Ashkenazi Jews, Cajuns, and French Canadians all have high proportions of Tay-Sachs (neither the Cajuns nor the French Canadians apparently inherited it from any purported Ashkenazi Jewish ancestors, but from separate mutations in their own, separate, small founder populations). But, no biologist would ever designate the Ashkenazi Jews (these days), the Cajuns, or the French Canadians as biological races of humans. Would you? Do you think the French Canadians are a biological race? Similarly, people of African descent do indeed have high rates of sickle-cell anemia. But the biological definition of race requires that some defining morphological characteristics of races must reliably distinguish members of those separate breeding populations. Have you ever seen a native Kenyan, an Ethiopian, and a Khoisan of South Africa? You would not confuse them if you had--you would definitely not assign them into the same breeding populations of "African descent" unless your conception of race was a simplistic and biologically meaningless "black/white." Other side of the coin, can you distinguish a unclothed Pima from an unclothed Navajo? I bet you can't. I can't. And no biologist would describe them as races, either. Heck, I had an old man talk to me about my tattoo in the grocery store the other day and at first I just thought he was a crazy old Phoenician from nowhere special at all. Turns out he was a Hopi, and he wanted to talk to me about my turtle tattoo, because turtles and tortoises are very important in Hopi origin stories (as they are in the origin stories of most Native American tribes). Lineages are much smaller than biological races, and biological races according to the definitions that we use to designate them within non-human species don't seem to exist in human populations. Some species have them, some species don't. We don't. That doesn't mean that the concept of biological race can't apply to humans, but we don't seem to have them, and probably haven't had them for a very, very long time. Indeed, we don't have as much genetic isolation of populations as some of us would like to think, and the amount of genetic variation between populations is much smaller than the amount of genetic variation within them. On the other hand, the popular and historical conception of "race" encompasses HUGE groups of people. You've never seen a government form with checkboxes for: Pima, Cajun, Ashkenazi Jew, French Canadian, Northern European. You never will. No biologist would ever consider them races and neither would any Joe Schmoe on the street. And, to bring it back to the point of the latest posts, this thread had become about the definition of race used by Joe Schmoe on the street (i.e., Wade, the OP, who used "Black," and Kuzco, who suggested that "people of color" have an inbred--that is, genetically based--fear of snakes). And as far as using Joe Schmoe-type race classifications to infer biological relatedness, or breeding populations, or anything close to resembling a historical biological reality of one group of people as distinct from the historical biological realities of other groups . . .
Well, ain't no way, no how.
