Saturday, July 28, 2007

Annoyance at trolls

After reading some utterly revolting commentary on Brendan's site (note: revulsion is not at all due to Brendan, who has no part in the racist commentary. He merely takes free speech seriously, and held his nose while allowing awful trash to spew out of the mouths of trolls), I am once again struck by the ability for people to be misinformed on science and try to use it in defense of their ridiculous notions. There's a lot of flat-out incorrect information out there concerning the biology of race, and I just eventually decided that I should say something about it.

1) It is technically incorrect to argue that there is only one human race. For this one, I blame a lot of science fiction writers for referring to sentient aliens as alien races. This, I believe, has caused people to think that race means the same thing as species; I admit when I was younger I was under that impression as well. In reality, a biological use of the word race is akin to that of breed: it is a group of individuals sharing common physical characteristics which differentiate that group from other members of the greater population. To this extent, there are human races, as it is indeed possible for most people on sight to distinguish, for instance, someone whose ancestry 1,000 years ago trace primarily to Europe from one whose ancestors at that time lived primarily in Australia. How many human races there are is up for considerable debate, but there are physical characteristics which differentiate people whose ancestry lies primarily in different geographical regions.

2) The fact that we can distinguish primary racial background from individuals with relatively low levels of population admixture in their background does not mean that we can distinguish racial background based on blood samples. There are a small number of known biological characteristics which are significantly more common in individuals of one population or another, which allows for a greater probability of guessing "correctly", but these are still probabilities. For instance, beta thalassemias are a class of blood disorders characterized by mutations in the splice sites of the hemoglobin beta protein. These are much more common in areas of the world with malaria, and different versions of the disorder are more or less common in various regions. If you have a blood sample showing a beta thalassemia of one particular type, you can say that it's more likely to be from someone with ancestry in Greece than a random blood sample is, for example. We can also use markers on things inherited from just one parent--the mitochondria to establish the matriline, the Y-chromosome to establish the patriline--and therefore trace a small percentage of any individual's genetic legacy fairly accurately. But this is only true for a small fraction of your genetic background, and it remains important to point out that ~85% of human genetic diversity remains within populations, and only ~15% exists between populations (Rosenberg et al, Science 2002). At the genetic level, humans are remarkably not diverse.

3) That being said, it is indeed possible for forensic scientists to make a determination about some racial characteristics from skulls. Morphometric data from skulls of individuals with low degrees of genetic admixture have some degree of differentiation which has been attributed to natural selection, particularly in characteristic regarding breadth and depth of nose (for example, Roseman and Weaver, Am. J. Physical Anthropol. 2004). However, I will also say from personal experience having looked at casts of human skulls, to the untrained eye the only difference among anatomically modern human skulls visible without the use of calipers is that of the Inuit v. all others, due to a distinct difference in roundness of the skull.

4) All of the above is written primarily about those rare populations where many generations of ancestry can be traced to the same geographical region. Particularly in modern times, though throughout human history and prehistory, there have been waves of migration and conquest, with substantial genetic exchange brought about therein. One consequence of the slave trade was indeed a greater degree of mixing of genetic information from Europe and Africa, more within the Americas than in Europe or Africa themselves. People often forget that we in the US are in a country of immigrants, and one in which significant amounts of genetic mixing have been common for centuries. If you take a random genetic sequence from you and two other individuals in this country, one who shares your self-described race and one who doesn't, unless the most recent common ancestor is within the past few generations you are not more likely to group with the person of your race than the person from outside it.

The level of information and logical reasoning in the commentary is severely lacking, from people arguing multiple different points of view. As a few quick examples for those who don't feel like reading the tripe: Black people are the descendants of Cain, and the mark of Cain is his ugly dark skin, and Cain was born from the union of Eve and the Serpent so therefore isn't a descendant of Adam like all white people are (let's argue against that with, say, Genesis 1:4 "Adam lay with his wife Eve and she became pregnant and gave birth to Cain"). Greeks have a lot of Black blood in them, black women and mixed race children are inherently ugly (let's go with, say, the fact that the woman the Western world has held up as the ideal of beauty for centuries was a Greek woman by the name of Helen. This, incidentally, lends itself to the wonderful unit of beauty, the miliHelen: the level of beauty required to launch a single ship). Or we have the assertion that north Africans ruled Europe for 700 years (um, really? When? And who were they? The Moors held the Iberian penninsula for about 8 years, but the only major conquering of Europe which lasted any appreciable length of time was Rome conquering almost everything else, but last I checked Rome was in Europe, not Africa. Africa did conquer Europe when our own ancestors moved in and displaced the Neaderthals, but that's not history so much as prehistory). Other such drivel abounds, and none of it's really worth my time debunking. But, as is my wont, I will go after some of the misstatements, lies, and misuse of science. Race is a complicated matter in both biology and anthropology. If you're going to try to make assertions about what these disciplines have to say on the matter, spend the time to actually read about it in reputable journals first.

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