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Health

The race question: are bonobos human?

Gene ExpressionBy Razib KhanFebruary 23, 2012 12:05 PM

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Recently Jason Antrosio began a dialogue with readers of this weblog on the "race question." More specifically, he asked that we peruse a 2009 review of the race question in the American Journal of Physical Anthropology. Additionally, he also pointed me to another 2009 paper in Genome Research, Non-Darwinian estimation: My ancestors, my genes' ancestors. Normally I don't react well to interactions anthropologists who are not Henry Harpending or John Hawks. But Dr. Antrosio engaged civilly, so I shall return the favor. I did read all the papers in the American Journal of Physical Anthropology special issue, as well the Genome Research paper. My real interest here are specific questions of science, not history or social science. But I will address the latter areas rather quickly. I am not someone who comes to this totally naked of the history or social science of the race question. I've read manybookson the topic. And as a colored person who has moderate experience with racism I get rather bored and irritated with excessively patronizing explanations of how racism afflicts us coloreds from white academics (non-white academics who focus on this subject are usually careerists or activists who don't have to make much pretense toward scholarly substance and can be duly ignored, at least in my experience). The main point which I think we can all agree upon is that colloquial understanding of race has only a partial correlation with any genetic understanding of race. I myself have ranted against the confusions which have ensued because of the conflation of the two classes, and it is certainly a legitimate area of study, but it is not my primary concern. And importantly, I have no great primary interest in battling racism. By this, I do not mean to imply that I support racism, or am personally against battling racism. When it comes to racists, broadly defined, I am not personally a great fan (as can be attested by my pattern of bans and rebukes). And when I say racism, I don't just mean white people behaving badly. I mean people who express racial nationalist sentiments in a crude and crass manner, and are often inappropriately assertive about the righteousness of their views (e.g., a few commenters have complained that I, an Indian [yes, I'm not technically Indian], should not talk so much about Westerners. Of course I view myself a Westerner, but to a racialist this is simply not even wrong. Naturally this is a chasm in world-views which is not reconcilable. Please note that some "anti-racists" would also agree I am not a Westerner, though mostly because they view that term as referring to evil white colonialists). Nevertheless, when it comes a study of human variation, or history, and the like, my primary aim is to enter into a state of intellectual Epoché. Whether Charles Darwin, Francis Galton, or R. A. Fisher, were, or were not, racists is of minor concern to me. I am not saying that it is irrelevant, but the fixation on racial prejudice is not part of my bailiwick. As I allude to above there are whole departments devoted to the presumed oppression of coloreds by Mighty Whitey, and I leave them to their joyful intellectual romp. But for many people ferreting out racism is more of a performative act. There's a big difference between revealed preferences and avowed preferences. For example, most Americans espouse a love of diversity. But they sure don't love diversity when it comes to who they date. These include many people who I know personally, who are diversity loving progressives, but who seem to fall into the trap of disaggregation. Since I don't love diversity and don't care about that issue I don't bring it up with them often. But it's what I call a revealed preference. Or, to give an amusing example, I said something offensive in one of my posts apparently a few years back, which prompted one outraged reader to leave a long shocked rant about my racism. The comment was trashed, and the reader banned. Nevertheless, I traced their Facebook account. The individual was a young white professional resident in San Francisco. And, their friends list was visible. I did a quick spot check, and estimated that ~90 percent of their San Francisco friends were white. In contrast, about ~50 percent of San Francisco's population is white. I'm not going to accuse anyone of racism, but there are quite interesting revealed preferences in the world (I saw this when I lived in Berkeley, where a few times I was the only non-white at a party where people were trashing how little diversity there was in Oregon when they found out that that was where I was from). Most people like associate with "their own kind," however that is defined. That's an observation. Not a judgement. I wish more people would withhold the judgement sometimes. Because I don't really care about diversity and all the the standard shibboleths common among the progressive set, I do sometimes like to point out the naked emperors here and there. Frankly a lot of the humanistic and social science literature on race strikes me as performative as well. There are some nuggets of truth, but they're usually trivially obvious. Segregation and genocide are generally agreed upon as bad. When the nuggets of truth are not trivial, they're often strongly normative. Moral tales told, not positive descriptions of reality. I, for example, do not favor affirmative action, and do not care if academic departments reflect the racial diversity of society at large. This is not a common viewpoint in some circles. If you are on a university campus, I invite you to go look at the headshots of the graduate students in ecology & evolution, and then look at neuroscience. Count the number of Asians. You may see an interesting pattern! So let's move to the science. Do races exist in human biology? Is it a useful concept? That depends on criteria in both cases. The reality is that I'm not sure I know what a species is in an axiomatic sense, let alone race (many biologists don't, that's why there's a whole area devoted to studying the issue of the definition). Rather, for me species are evaluated instrumentally. Is the classification of a set of individuals as a species useful in illuminating a specific biological question? Species are human constructions, categories which are mapped upon reality. That doesn't make them without utility. Many of the same "where do you draw the line?" questions asked of race can be asked of species. In a deep ontological sense I don't believe in species. But in a deep ontological sense I don't accept the solidity of a brick (most of the volume is space of any object of course!).

800px-World_population_density_1994.png

Moving onto specific objections, some observe that genetic variation is clinal. This has a basis in fact, more or less. But the distribution of grades is also clinal. Nevertheless, professors generally look for "natural breaks," and then distribute A's, B's, and C's, accordingly. In concrete terms groups like the Tuareg and Uyghur are equidistant between West Eurasians and Africans and East Asians, respectively. But look at the map of the Old World's population density. The variation in gene frequencies may be clinal, but that ignores the reality that the genetic clusters themselves have different weights varying as a function of space. The Tuareg are few. The "donor" populations on either side of the Sahara are many. If you want to look for "natural breaks," you look to the empty spaces, where there will be populations, but very few. Additionally, there is the question of history. We know that the Uyghur are a new population, which emerged in the past 2,000 years due to admixture between a resident West Eurasian population, and Turkic groups. We know this both through genetics (decay of linkage disequilibrium) and history. There is also a great deal of circumstantial evidence that the West Eurasian forebears of the Uyghurs, the Tocharians, were long distance migrants from the west. So who were the indigenes of the Tarim? It may be that due to the local ecology the center of Eurasia has long been relatively underpopulated in relation to the peripheries, with the emergence of new lifestyles (e.g., oasis agriculture, nomadism) resulting in the ethnogenesis of groups which arose recently to occupy the midway position between Europeans and East Asians. This does not mean that I believe that before 5,000 BC the gene flow between East Asia and Western Eurasia was zero. Rather, I think there are lots of data which imply that it was simply very low (the East Asian admixture among Tatars in Russia, and the West Eurasian admixture among Mongols, both show evidence of being relatively recent, due to the rise of horsemanship). This is in contrast to the more genuine cline and isolation-by-distance you see from Europe down to the Middle East, and to a lesser extent South Asia. Actually, until recently I would have said into South Asia without qualification, but I am now convinced that South Asia itself has been the scene of an admixture event of huge scope within the last 10,000 years. Much of the discussion that Jason Antrosio alludes to discusses the problems which have emerged from hypothesis based admixture inference programs, such as Structure, frappe, and Admixture. The main issue is that many people read them naively. This includes people in the academic community. But this does not mean that no one understands the problem. I've talked to evolutionary genomicists who have complained about the misinterpretations, and I am quite aware of the artifacts which can flow out of the software. Anyone who has used Admixture knows very well the problems. For example, South Asians often emerge as a distinct cluster, but the research above indicates that they are a stabilized hybrid! This is why I told some of Antrosio's commenters to be careful about hitching their wagon to isolation-by-distance and clinal variation; there is some evidence that many of the world's populations extant today are the product of relatively recent hybridizations between previous rather distinct groups. There's no need to invoke Platonic original races. Rather, it may simply be that in the random lottery of cultural adoption some groups invented agriculture, and replaced many populations which exhibited a clinal variation. And that's the key: racial typologies are coarse reflections of genuine history. In other words, race is a reflection and reification of genuine lower level dynamics, it is not the prior phenomenon. This sidesteps many of the technical complaints which arise in the papers Antrosio linked to. I can quibble with them well enough though. For example, figure 2 in the Genome Research paper relies upon a rather shitty (in relative terms) genetic relatedness statistic, IBS, in my opinion. Don't take my word for it, play around with data sets in Plink and you'll see what I mean. It tends to be history-blind. My parents, who are South Asian, but with a non-trivial East Asian component, are often clustered with a host of other South Asians who also have non-trivial East Asian components. This is a real result, but it ignores the history that all that is common across these individuals is a particular admixture pair. It's not a "real" cluster, reflecting real shared history. A more interesting concern is the fact that in most trees non-Africans tend to be on their own branch, while Sub-Saharan Africans tend diversify into distinct basal branches. The question ensues: are Sub-Saharan Africans several distinct races? Using evolutionary history as a measure I would say yes! This is definitely one area where social expectations have led us astray. It turns out that it may be that the Bushmen/non-Bushmen separation is only 1/3 as long ago in the past as the Neanderthal/modern human separation. In fact, the Bushmen may predate, and not be part of, the "Out of Africa" event. Along with the Pygmies and Hadza there seems to be a very ancient differentiation between the agriculturalist and hunter-gatherers in the African continent. For me these details of history are fascinating. But going back to normative concerns: is there a worry that Bushmen will be dehumanized if it is understood that they are not part of the modern human expansion event circa ~80,000 years before the present? Unfortunately, I don't think that science matters much in this case. The Bushmen have been dehumanized for hundreds of years. The Pygmy of Central Africa have also been dehumanized. All without science. An understanding of our evolutionary history is informative, but I doubt it is the prime motor for the great injustices of history. The 19th century race science which modern biologists and anthropologists revile (to a great extent, rightly) did not give rise to the race system of the West. Look at the history, and you see that its genesis predates Darwin by decades. Science may have been a supporting argument, but this was thesis looking for talking points. The Bushmen are human. The Bonobos are not. Why? I don't think it has been definitively proven that modern humans and Bonobos are not inter-fertile. Granted, the separation between the Bonobos and humans are about two orders of magnitude greater than Bushmen and other humans, but there is some evidence that Bushmen have admixture from archaic lineages diverged nearly 1 million years into the past, pushing elements below a magnitude! Where do you draw the line? Species are a typological concept, but usually as a pure categorical typology the class is useless. Rather, it's a tool, a framework. What you do with a tool, well, that's a different thing altogether....

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