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512QZUX2sSL._SX331_BO1,204,203,200_ Over at The Genetic Literacy Project Jon Entine has a post up, Usain Bolt’s Olympic gold proves again why no Asian, white–or East African–will ever be crowned world’s fastest human. Fifteen years ago Jon wrote Taboo: Why Black Athletes Dominate Sports And Why We’re Afraid To Talk About It, so he knows something about this topic.

Actually, I think Jon is wrong on this. Better drugs and biological engineering mean that I suspect at some point in the near future the fastest “human” alive is going to be non-African, and, if I had to bet, Chinese. But you know what Jon meant.

There is a lot of detail in Jon’s post because he knows a lot about this topic. But at the end of the day the specific details are less important than the general theoretical framework, which makes it unsurprising that a single group of humans who are genetically related dominate sprinting. Unlike figure skating, sprinting is entirely objective. All that matters are physical inputs. Second, unlike swimming, which is also objective, sprinting seems to have pushed very close to the boundaries of what non-modified or drug-enhanced individuals are capable of. To my knowledge there’s no expectation of a Fosbury Flop in sprinting.

Therefore, sprinting is selecting for raw ability. Training is not irrelevant, but the issue with training is that others can train too. What can’t be mimicked is raw ability due to one’s biological aptitudes and abilities (again, excepting bioengineering). Let’s assume that Olympic caliber sprinters are among the 10,000 fastest humans on the planet, because not all people with the aptitudes become sprinters. Assuming a normal distribution, that’s about five standard deviations above the human norm. I suspect I’m being conservative. Someone like Usain Bolt is probably a six standard deviation unit human. Google tells me that a fit human can run the 100 meter dash in 13.5 seconds. The world record is about 9.5 seconds. The absolute range here is not incredibly large. Small differences in the mean across populations suggest that when you select for extreme individuals those small differences will make all the difference.

If sprinting was less objective, then there would probably be more equality in outcome. I suspect judges would be biased for various reasons, and one set of nations or people of a particular ethnic background dominating a field can get quite embarrassing. But sprinting is rather objective, and the socioeconomic obstacles are low. Given basic nutrition, and the ability to huff it, you have a shot. What matters is the magnitude of your ability.

principlespopulationgenetics One peculiar thing population genetics teaches us that non-adaptive traits are more heritable. This is due to the fact that selection tends to remove variation, selecting for fitter individuals. Humans are good runners, there are entire evolutionary theories based around our biomechanical modifications and adaptations. But there’s really no benefit in running in bursts of 10.5 in the 100 meter dash vs. 9.5. We’re not that sort of ambush predator. There’s probably some heritable variation in burst ability, but it’s small, and not visible in any normal set of tasks among large groups of humans.

But modern competitive sports at the Olympic level is not selecting for normality, it’s selecting from outliers. It isn’t that West Africans were guaranteed to be the best sprinters, it’s just that a priori it shouldn’t be surprising that in such a non-adaptively beneficial trait as running a few seconds faster in the 100 meter dash some populations had the genetic die loaded in their direction.

Note that I’m not denying any sort of selective or adaptive argument. There’s a fair amount of evidence that there is some selection in favor of greater height in Northern Europeans vs. Southern Europeans, which probably explains why Lithuanians are more prominent in basketball in relation to their numbers than Italians. But the selection wasn’t for basketball, and the fact that there is heritable variation suggests that selection wasn’t that strong and unidirectional….

Humans vary. Populations vary too. When you select from the tails of the distribution, the differences between populations are going to be very noticeable. If a sport is objective, and pushing its limits, it will select from the tails of the distribution.

 
• Category: Race/Ethnicity, Science • Tags: Race, Sports 
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twitterethnicitychart

Twitter workforce breakdown

diversity_brief_fig2 The above statistics on the labor force at Twitter compared to the overall labor force indicate that non-Hispanic whites are underrepresented in tech firms in Silicon Valley. This is true overall in prominent tech firms. 51% of Facebook’s employees are non-Hispanic whites.

So how to make sense of these sorts of articles:  Twitter’s White-People Problem? And what about passages such as this which seem to totally defy statistical/demographic reality:

 But while Twitter the platform is bustling with all types of racial diversity, Twitter the company is alarmingly white.

Twitter isn’t alone. Most of the biggest tech companies in Silicon Valley are overwhelmingly white and male. While blacks and Latinos comprise 28 percent of the US workforce, they make up just 6 percent of Twitter’s total US workforce and six percent of Facebook employees.

Of course this is just a lie. Very few people would say a workforce that is 50 to 60 percent white, true of both Google and Microsoft, is “overwhelmingly white.” In fact, it’s less non-Hispanic white than the US labor force as a whole. I’ve linked to statistics in this very piece. They take about 10 seconds of browsing search queries to understand this.

But you don’t need to know statistics. Eat at a Google cafeteria. Or walk around the streets of Cupertino. There is no way that one can characterize Silicon Valley as overwhelmingly white with a straight face. Silicon Valley is quite diverse. The diversity just happens to represent the half of the human race with origins in the swath of territory between India and then east and north up to Korea.

The diversity problem isn’t about lack of diversity. It is about the right kind of diversity for a particular socio-political narrative. That’s fine, but I really wish there wasn’t this tendency to lie about the major obstacle here: people of Asian origin are 5% of the American work force, but north of 30% in much of the Valley. If you want more underrepresented minorities hiring fewer of these people would certainly help. In particular the inflow of numerous international talent coming from India and China could be staunched by changes to immigration law.

But these are international companies. Though they genuflect to diversity in the American sense (blacks and Latinos), ultimately they’ll engage in nominal symbolic tokenism while they continue on with business, with an increasingly ethnically Asian workforce and and increasingly Asian economic focus. Meanwhile, the press will continue to present a false caricature of a white workforce because that’s a lot more of a palatable bogeyman than Asian Americans and international tech migrants, and the liberal reading public seems to prefer the false narrative to engaging with reality.

Addendum: The first article was in The Nation. Take a look at their masthead. Most of the names I recognize are mighty, perhaps even alarmingly, white….

 
• Category: Race/Ethnicity • Tags: Race 
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Youngronaldfisher2In New Creationists a philosopher at Duke recounts his experience when he attempted to explore the implications of group differences in ethics. He stated:

After reading some recent work on the biology of group differences last summer, it occurred to me that as an ethics professor, I should write something about the moral upshot: if there are such differences, what are the consequences for how we should treat one another? Should we support policies that attempt to equalize opportunities only if they produce equal outcomes?

My conclusion was modest: if there are biological differences between groups, and if, as Lee Jussim has argued, some stereotypes turn out to be accurate in part because of correct generalizations about biological differences, these facts should not undermine our commitment to treating one another as moral equals, or to increasing opportunity for all, regardless of group membership.

But I had committed a sin in the eyes of the two referees who read and commented on my paper. I simply acknowledged the possibility of group differences while arguing that whether or not they exist, they should not matter. For having done that, the two journal referees used expletives and exclamation points to give the most venomous and dismissive feedback I have ever encountered. (Needless to say, the paper was not accepted for publication after such hostile comments.)

 

This is obviously a touchy subject to many reasons. But, the extremely vehement reactions on this topic reveal an aspect of how ideas are policed in our society. Because I have a particular reputation I am privy to viewpoints from many people that they would be terrified to share with others. For example, many young geneticists seem to view the idea that “race is a myth” to be a noble lie.

There are legitimate issues in regards to phylogenetic classification systems. But, the key that many geneticists have noticed is that the lay public makes incorrect inferences from the assertion that “race is a myth.” For example, many people are confused as to why human populations exhibit structure, and one can generate phylogenetic trees. That’s because people translate the idea that race does not exist to one where human population structure is arbitrary and trivial. The conclusion obviously does not follow, depending on your definition of race. But I think one can see how the educated public is coming to these conclusions.

Here’s an article from the year 2000 in Do Races Differ? Not Really, Genes Show:

Scientists have long suspected that the racial categories recognized by society are not reflected on the genetic level. But the more closely that researchers examine the human genome — the complement of genetic material encased in the heart of almost every cell of the body — the more most of them are convinced that the standard labels used to distinguish people by “race” have little or no biological meaning.

They say that while it may seem easy to tell at a glance whether a person is Caucasian, African or Asian, the ease dissolves when one probes beneath surface characteristics and scans the genome for DNA hallmarks of “race.”

On the one hand there is an aspect of this article which is almost quaint. Note the references to 80,000 genes and such. But the general spirit captures the modern Zeitgeist well, and it is not dated at all. The idea of race implicit in this piece, and commonly held by the general public, is typological. That is, races are like Platonic ideal forms, and genes and traits are used to explore these ideal forms.

This is false. Races are not like ideal forms. That’s in part because modern human populations are by and large the consequence of massive admixture events between deeply diverged lineages. But, that does not negate the reality that population structure is a robust phenomenon, and, that its consequences are not trivial. My hunch is that some of the eye rolling that I’ve seen when younger geneticists refer to the idea that race is a myth has to do with the fact that population structure is such a big deal for genome-wide associations.

One of the implications of the above passage is that visual inspection allows for a clearer differentiation between individuals from different populations than genetics. This is false. As it happens the groups referred to above are among the most differentiated, as they don’t share common ancestors for ~40,000 years (South Asians on the other hand share ancestry with both “Caucasians” and “Asians” over the last 40,000 years), and are positioned at the extremities of the Afro-Eurasian world island. Genomics actually gives a clearer and more precise picture of population genetic differences.

The problem, if there is one, is that these population genetic differences are not necessarily good fits if one assumes a Platonic model of racial categorization. I think this explains the irritation and frustration with people who are confused as to the ancestral quantification results from firms like 23andMe. The results are true, and robust, reflections of genetic variation. But population groups are reifications, attempting to squeeze human digestible insight from systematic variation at hundreds of thousands of markers whose pattern of differences are a consequence of tens of thousands of years of population history.

Which brings me to the UNESCO statement on the Race Concept. Published around 1950 in a few versions these statements were signals that there was a change in the winds after World War II. Much of today’s conventional wisdom is prefigured in these statements. But if you read the 1952 version much of it is pretty moderate and I think it would be seen as “problematic” by many thinkers today. There are many familiar names (and some not familiar to me) in terms of scientists consulted. E.g., H. J. Muller, Theodosius Dobzhanksy and Ernst Mayr. But for me R. A. Fisher’s comments stood out. I knew he was a dissenter from the statement, but I’m going to cut and paste the whole section from him because I think it’s pretty interesting (and many might agree with him):

In so far as the Statement condemns any defamation of races and emphasizes the appalling nature of the recent abuse of racial theory, it has my full and unqualified approval. I wholeheartedly agree, also, with its explicit and implicit finding that anthropology and racial studies afford no justification for the assumption that members of any particular race are not entitled the enjoyment of all fundamental rights, or for any form of racial discrimination. And I am very glad that, after all the horrors that have been perpetrated, these principles should have been enunciated clearly and publicized widely by an organization of such standing and by distinguished men as the authors of this Statement.

But the Statement also purports to be an authoritative body of scientific doctrines, and this is quite a different matter. Without touching upon the content of these doctrines, and quite apart from whether or not they meet with my approval, I must register my fundamental opposition to the advancing of scientific theses as such, and protest against it.

I recall the National Socialists’ notorious attempts to establish certain doctrines as the only correct conclusions to be drawn from research on race, and their suppression of any contrary opinion; as well as the Soviet Government’s similar claim on behalf of Lysenko’s theory of heredity, and its condemnation of Mendel’s teaching. The present Statement likewise puts forward certain scientific doctrines as the only correct ones, and quite obviously expects them to receive general endorsement as such. I repeat that, without assuming any attitude towards the substance of the doctrines in the Statement, I am opposed to the principle of advancing them as doctrines. The experience of the past have strengthened my conviction that freedom of scientific enquiry is imperiled when any scientific findings or opinions are elevated, by an authoritative body, into the position of doctrines.

A different section of statement relays Fisher’s view of the empirical realities, which would make him extremely unpopular today:

Sir Ronald Fisher has one fundamental objection to the Statement, which, as he himself says, destroys the very spirit of the whole document. He believes that human groups differ profoundly “in their innate capacity for intellectual and emotional development” and concludes from this that the “practical international problem is that of learning to share the resources of this planet amicably with persons of materially different nature, and that this problem is being obscured by entirely well intentioned efforts to minimize the real differences that exist”.

This sort of comment from Fisher makes sense in light of his personality. I’m tempted to think that today he would be diagnosed as being “on the spectrum.” Arguably the most eminent evolutionary geneticist of the 20th century, he also made many original contributions to statistics. But as documented in his daughter’s biography of her father, he was a monomaniacal and selfish person, who lacked many social graces. There is a section in R.A. Fisher: The Life of a Scientist which documents his tendency to engage in arguments with people who shared his general conclusions on a given topic, but where he believed they engaged in fallacious reasoning (in this he seems to resemble Karl Popper). This tendency is clear above. Though he agrees with a broad liberal humanitarianism which looks darkly upon considerations of race, he disagrees with the presumption that these values are rooted in empirical facts.

Finally, I want to quote page 238 of my edition of The Genetical Theory of Natural Selection:

The general consequences of race mixture can be predicted with confidence…Their general character will therefore be intermediate, but their variability will be greater than that of the original races. Morever, new combinations of virtue and ability, and of their opposites, will appear in the mixed race, combinations which are not necessarily heterozygous, but may be fixed as permanent racial characters. There are thus in the mixed race great possibilities for the action of selection. If selection is beneficient, and the better types leave the greater number of descendants, the ultimate effect of mixture will be the production of a race, not inferior to either those from which it sprang, but rather superior to both, in so far as the advantages of both can be combined. Unfavorable selection, on the other hand, will be more rapidly disastrous to a mixed race than to its progenitors. It should of course be remembered that all existing races show very great variability in respect of hereditary factors, so that selections of the intensity to which mankind is exposed would be capable of producing rapid changes, even in the purest existing race.

41PHSZN6AEL Fisher was writing this in the 1920s. This was near the tail end of the peak of white supremacy across the world. Charles Davenport, the director of Cold Spring Harbor Laboratory, published Race Crossing in Jamaica in 1929. It presented a view where mixed-race children suffered due to crossing between diverged lineages. This was not an atypical view at the time. The man whom Fisher succeeded to a great extent as Britain’s most eminent statistician, Karl Pearson, was a socialist and feminist (Fisher was a political conservative whose views on women were more regressive than Pearson) who also believed that inter-group competition with “inferior races” was a major driver of the evolutionary progress of Europeans. The above passage shows that Fisher’s logical mind internalized Mendelianism and its necessary implications to such a great extent that as early as the 1920s he was already dismissive of the racialism ascendant at the time. But by the 1950s the dominant viewpoint differed, and here Fisher again stood his ground, not changing the things he had written in the later eugenic sections of tGToNS.

Note: R. A. Fisher had some unfortunate views on smoking. See When Genius Errs: R. A. Fisher and the Lung Cancer Controversy.

 
• Category: Race/Ethnicity, Science • Tags: R. A. Fisher, Race 
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Olivia Munn

Olivia Munn

Periodically rather than offering up original thoughts it is needful to engage defensive warfare against pernicious memes. For example, one thesis that is commonly bandied about today is that racial admixture will result in the blending away of all differences, toward a homogeneous beige future without end. This is false. It is false for several reasons, genetic, and sociological. But, it is persistent for ideological reasons.

Here’s the latest instance, Future Humans Will All Look Brazilian, Researcher Says:

Meanwhile, many other physical traits will simply blend together. “Most of the traits that we think of as distinguishing different groups (hair colour, skin colour, hair curliness, facial features, eye shape) are controlled by multiple genes, so they don’t follow a simple dominant/recessive pattern,” McDonald explained. “In those cases, blending will make people look more similar over time.”

Hazara

Hazara

The recourse to a blending analogy is unfortunate. Genetics is not a blending process, it is a discrete one, which reconfigures variation every generation. The underlying variation in the form of alleles is maintained, even if the genotype frequencies shift. This insight is implied in the article with talk about recessive phenotypes and nods to Hardy-Weinberg equilibrium. One of the key problems with Charles Darwin’s original theory of evolutionary process is that it did not account for how heritable variation could be maintained. If that variation melted away every generation through blending processes then the world would rapid equilibrate toward homogenization. Roughly half the variation would disappear per generation in an exponential decay process.

41PHSZN6AEL And yet variation remains! Though the phenotypes, the traits, may exhibit blending between parents, the underlying genetic variation is governed by Mendelian dynamics. This is why in populations where alleles for traits like pigmentation segregate in a polymorphic fashion, such as in India, it is not uncommon for complexion to vary within families. Though on the population wide scale there is some tendency toward clustering about the mean, variance remains within a random mating group at equilibrium.

Another major issue is that these discussions too often focus on single traits. When evaluated across loci the variation and range in possibilities due to admixture in fact results in greater diversity than is possible today. Mendel’s law of independent assortment implies that traits and variation will not be co-inherited. Before international travel and migration the possibility of someone with blue eyes, an epicanthic fold, and tightly curled hair, was a theoretical affair. Today there are almost certainly people who exhibit all these traits.

By coincidence these people are likely to be Brazilian, as this is a nation where there are large populations of African, Japanese, and Northern European (German) ancestry. And the example of Brazil itself illustrates empirically why homogenization will not proceed in the manner which intuition tells us. Brazil may be modally a brown nation, but its physical types run the gamut, expressing the underlying genetic variation. Among populations such as the Uygurs, who are fusion of eastern and western streams, individuals arise who reflect in near totality the physical types of only one of their ancestral populations, even if most individuals exhibit configurations in equipoise.

And so it was, and so it will be. The reality is that today is not the age of amalgamation, that age has passed. The most recent work in human genomics actually brings us to the conclusion that in fact most of the “pure” populations we see around us today are fusions of deeply diverged human evolutionary threads. The ancestors of Europeans in the Pleistocene were as differentiated as modern continental races (i.e., Fst on the order of 0.05 to 0.15 depending on the pairwise comparison). The same is true of South Asians, and most other groups you can think of. The “Great Mixing” after the retreat of the ice and collision of peoples may explain why there is so little evidence for hybrid inviability today in cross-racial pairings; it may have been purged from the genomes of modern groups through selection during that period.

The admixture of this age will be but a shadow of the past. The reality is that for centuries into the future huge numbers of people will persist who we might recognize as European, African, and East Asian, in totality of their form and genetic heritage. The amalgamation of the early Holocene probably occurred through the fusion of groups in the early stages of demographic expansion. They were tribal affairs, parochial in their scope, born out of desperation and chaos, even if the consequences were continental in their implications. The clans of yore became the mothers of nations, but those nations are mature and endless in their number now. The existence of Brazil as we understand it is exceptional, the product of racial slavery on a massive scale during a time of tumult. It is the exception, rather than the norm.

Rahul Gandhi

Rahul Gandhi

In the next few decades international elites will no doubt enter into a period of intermarriage as old barriers fall, and new commonalities of class transcend ethnicity. But for the majority of the citizenry of the old nations such considerations will be theoretical. The initial period of synthesis and cross-fertilization will give way to stasis as all those open to the new possibilities of finding mates across old racial categories will have done so. Those who remain, the majority, will be more conservative in their preferences and tastes. The Holocene ushered in races which are extant across the world today through admixture; the anthropocene will usher in the post-national international race of global elite. Rather than twining a few threads of the human lineage, this new population will twist all the threads together in a radical new conformation. And it will be anything but homogeneous and uniform in its expression!

 
• Category: Race/Ethnicity, Science • Tags: Genetics, Race 
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PhylogeneticTree“Tree thinking”, just like “population thinking”, is essential to understanding evolutionary biology. But there are problems with this. First, even on a macroevolutionary scale there is massive violation of separation between the branches of the tree of life due to lateral gene flow, whether directly or mediated via viruses. As you drill down to a finer phylogenetic grain the issue of reticulation, the transformation of a tree into a graph, becomes something you have to integrate into your model. This is one reason that TreeMix was developed, it allowed one to model gene flow across the branches of trees on a microevolutionary scale. But there’s another major issue, and that is of clines. The “graph” generated by TreeMix still models pulse admixture events. But a lot of genetic variation is generated in the context of isolation by distance dynamics. There are no singular events where populations mix, rather, every instance is part of a continuous process of mixing.* An excellent illustration of this scenario is a ring species.

When generating a “tree of life” it seems that it behooves us to take these details into account, because to a great extent the details are really what we’re interested in now (OK, at least if we’re population geneticists). Each species or section of the tree of life may exhibit different local dynamics, just like the topography of our planet exhibits local variation. Some regions may be subject to far greater gene flow across the branches rather far from the tips (e.g., plants), while others exhibit rather less (e.g., some mammalian lineages). As far as humans go, about 10 years ago a hybrid tree-cline model seemed viable, as outlined in Ramachandran et al., a serial founder event out of Africa, and then equilibration with isolation by distance, leading to a clinal overlay upon the branching process. After Pickrell et al. I think that this model just can’t suffice. Rather, there were powerful pulse admixture events due to meta-population dynamics and large scale demographic implications of cultural change over the last 10,000 years, which wreaked havoc with patterns of human genetic variation. As on the larger tree of life the dynamics which characterized particular segments of the human phylogenetic tree/graph vary. In the New World Ramachandran et al.’s original formulation might actually be rather good south of the Rio Grande. In contrast it just doesn’t work very well in South and Southeast Asia, which has been subject to a great deal of genetic change over the past ~10,000 years, well after the Out of Africa event (in these two cases there look to be pulse fusions between very distinct branches of the human phylogenetic tree in recent history).

These thoughts were stimulated in part by comments over at 3 Quarks Daily [link fixed] in response to an Omar Ali post where he mirrored content from this weblog. This elicited two broad reactions. First, some readers objected to Omar posting content from me because I’m a conservative who holds views taboo to the liberal mainstream of that website. Because obviously that’s what being liberal is, knowing what to believe, and not giving any voice to beliefs and viewpoints outside of what you label to be right, true, and orthodox.** But a more interesting objection is to those who think that my adherence to the race concept is not supported by science. Here I feel like I’m talking to Creationists, they know what they believe, but they don’t know much about what they don’t believe. Most Creationists don’t really know much about evolutionary biology, they just know their talking points. Similarly, many who object to my acceptance of the validity of the race concept just trot out talking points. Intriguingly there is a similarity to the objections by anti-evolution Creationists and anti-population structure Creationists: a fixation on Platonic categories/kinds. A major confusion that anti-evolution Creationists exhibit is that species, “kinds”, are clear and distinct categories. They’re not. So many of the critiques fail at the get-go, because when you reject a Platonic idea of species the rejection of anti-evolution Creationism is almost axiomatic. The same aspect of disagreement emerges when arguing with anti-population structure Creationists. First, they don’t know the literature, so their objections are often weird and ad hoc. That’s fine. But the bigger problem is that I don’t hold the Platonic model of population structure they seem to think I must hold. Rather, our terms or categories are only useful in an instrumental sense. Their validity or lack thereof reflects how well they model the real processes which shape the genealogies which collectively define particular populations. I can try to get this viewpoint across, but since I hold views which disagree with their views (or so they think) and so naturally am wrong, I generally don’t make much headway.

* This is where Gideon Bradburd’s SpaceMix should help. The preprint will be out soon….

** This is a joke. I’m aware there are many liberal readers of this website. But, you must admit that it’s pretty funny how narrow-minded people who label themselves “liberal” can be! E.g., the fact that I’m a self-described conservative is reason enough not to give voice to my ideas.

 
• Category: Race/Ethnicity, Science • Tags: Population Structure, Race 
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mexicanThe image to the left is the ‘average’ face of a Mexican woman as generated by the University of Glasgow Face Research Lab. Aside from the fact that the face is prettier than the typical human because of the well known tendency of averaging facial features removing unattractive asymmetry it is racially what you might expect, a synthesis of an Amerindian and European face, with an Amerindian skew. But a phenotypic average only tells you so much. Variation is one of the key ingredients in evolutionary processes, and by getting a sense of a population’s variation you can infer things about its past and possible future history. For example, if that variation is heritable, then it is amenable raw material for adaptation. In contrast, if the variation is due to environmental parameters then it is not going to be appropriate input for adaptation via natural selection. In a nation like Mexico we see the full range, from ‘typical’ Amerindian phenotype, to someone who looks to be fully European (with a small minority with visible African ancestry).

But if the phenotype is heritable, then underlying this variation is genotype. The extent that genotype controls the variation is contingent upon heritability. The heritability of behavioral phenotypes is often around ~0.5. But for physical traits such as height or pigmentation the heritability is much closer to 1, on the order of ~0.8 to ~0.9. That means 80 to 90 percent of the variation of the trait across the population is due to variation in the genes. When we code someone as “Amerindian” or “European” or “African” we are assessing phenotypes with a strong underlying genotypic component. A new study in PLOS GENETICS outlines just how this plays out in Latin America, a region of the world which has the virtue of being a living experiment in admixture between different geographic races over the past 500 years.

Admixture in Latin America: Geographic Structure, Phenotypic Diversity and Self-Perception of Ancestry Based on 7,342 Individuals:

The current genetic makeup of Latin America has been shaped by a history of extensive admixture between Africans, Europeans and Native Americans, a process taking place within the context of extensive geographic and social stratification. We estimated individual ancestry proportions in a sample of 7,342 subjects ascertained in five countries (Brazil, Chile, Colombia, México and Perú). These individuals were also characterized for a range of physical appearance traits and for self-perception of ancestry. The geographic distribution of admixture proportions in this sample reveals extensive population structure, illustrating the continuing impact of demographic history on the genetic diversity of Latin America. Significant ancestry effects were detected for most phenotypes studied. However, ancestry generally explains only a modest proportion of total phenotypic variation. Genetically estimated and self-perceived ancestry correlate significantly, but certain physical attributes have a strong impact on self-perception and bias self-perception of ancestry relative to genetically estimated ancestry.

The phylogeographic aspect of this paper is not too interesting to me, as it confirms what we’ve known (e.g., more Amerindian ancestry in northern Brazil, Mexicans are somewhat more Amerindian than they are European, etc.). Rather, the biggest findings are those which relate physical appearance, self-identity, and genetic ancestry. In Europe someone who identifies as “white” is invariably ~99% European when assessed using a genetic method (the ~1% balance is often from Iberia). More precisely, white Europeans are ~99% West Eurasian, since a non-trivial amount of trans-Mediterranean gene flow has occurred, meaning there isn’t a clear boundary between Europe and nearby regions. Similarly, in Sub-Saharan Africa someone who identifies as “black” is likely to be nearly all Sub-Saharan African. This is often not the case in Latin America. That is, those who identify as “white” or “black” often have substantial admixture from other geographic racial groups.

One of the major drawbacks of this study is that it relies on 30 ancestrally informative markers (AIMs). Though this is acceptable in forensics, some of the ancestry inferences made on an individual basis are a touch less accurate than they would be on a dense marker SNP chip (e.g., the 650,000 SNPs used on the HGDP). The modest correlations here are probably a little lower than they would be if the ancestry was more accurately adduced. But in the broad sketch the conclusions are likely defensible. One result which may surprise then is the very modest correlation between physical traits and ancestry. Here’s the quote from the paper:

Regression of phenotypic variation on genetic ancestry (taking Native American as reference) demonstrates a significant effect for most of the traits examined (p-value <10−3 using a conservative Bonferroni multiple testing correction, Table 2). Among the non-facial phenotypes (accounting for sex, country, age, educational attainment and wealth) higher European ancestry is associated with: increased height, lighter pigmentation (of hair, skin and eyes) (Figure S6), greater hair curliness and male pattern baldness. Hair graying approaches statistical significance (p-value 10−2). Higher African ancestry is associated with: increased height, higher skin pigmentation and greater hair curliness. The proportion of phenotypic variance explained by ancestry is highest for skin pigmentation (19%) followed by hair shape (8%) and color of eyes and hair (4% and 5%, respectively) but at most 1% for the other phenotypes.

As I said it could be that the AIMs aren’t quite as accurate as they should be, and are underestimating the ancestral fractions on the individuals at the extremes (e.g., someone who is 100% European is estimated to be 95% European, because the marker set lacks precision). So you might bump up the proportion of variance explained a bit, but likely this still seems way too low to you intuitively. There are a few things going on here. First, skin color is controlled between populations by a relatively small set of genetic loci. This means that in admixed populations the sample variance, the random draw of genotypes across the loci, is going to vary a lot even in individuals with the same ancestry. Because of the relatively small number of large effect loci skin color is a trait which shows a lot of variation within families where ancestry is geographically diverse. And within families, or at least across full siblings, total ancestry is not going to vary that much. Second, for some of the “traits” in question that are being measured there is just a lot of variation within geographic races. It makes sense that ancestry would explain only a small fraction within this pooled data set. And yet people can recognize a set of features which are clearly European or Amerindian or African. I think the answer here is that you are picking up on correlation structure across the traits. A suite of subtle facial contours for example connote “European” in a Gestalt manner, even if quantitatively each contour trait has a lot of variation within a population and overlaps across them.

Where this all “cashes out” though is in the intersection of the sociocultural and biological. Within the paper itself they observe a few trends which would not be surprising. Skin color and hair form are very salient characteristics, and lead individuals to shift their estimates of their own ancestries. Those with lighter skin tend to overestimate their European ancestry fractions, while those with curlier hair overestimate their African ancestry. These are traits which have the characteristics that they are quite ancestrally informative to particular geographic races, and, very visible (unlike, say, Duffy status). Within these data there are also particular patterns which are intriguing and less obvious; those with low amounts of Amerindian ancestry underestimate the fraction, while those with higher levels overestimate it. The details of these patterns are obviously contextual in terms of time and place (e.g., in Henry Louis Gates Jr.’s genealogy specials many celebrities seem to yearn for exotic lineages, which would not be the case in past decades). What is more interesting is that fine grain patterns of variation in genetic ancestry and how they deviate from perceived ancestry can finally allow social scientists to get a better grip on patterns of discrimination (or lack thereof). It is not entirely uncommon in Latin America for full siblings to sometimes be socially perceived to be different races because of the random segregation of salient characteristics. In the aggregate these sorts of cases would allow one to estimate the effect of social perceptions, slights, or advantages. With the genetic dimension one could also ascertain the possibility of group differences, because many subtle characteristics are going to track genome-wide patterns, rather than a few phenotypes which society privileges when sorting people by geographic origin.

 
• Category: Race/Ethnicity, Science • Tags: Genomics, Latin America, Race 
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When I was watching Boyhood I assumed that some moron would point out that the protagonist’s social milieu was overwhelmingly white. And it’s out: Not Everyone’s Boyhood. Many of my friends have a hard time accepting I identify as conservative, but reading stuff like this makes it clear why I’m conservative, I feel like puking over this sort of critique because I think it’s totally dishonest. I feel confident that most of the white writers at The Atlantic, where the piece was published, had white childhoods, with white friends. If you look at the General Social Survey, and I have, around 50 percent of white liberals haven’t had a black person over for dinner in the last few years. And there was the media buzz recently about the fact that white people have white social networks. A clear case of “no shit” social science.

That is all fine. The writer of the piece on Boyhood is someone named Imran Siddequee, who is I’m sure working hard to make a career as a race hustler. And that’s good as far as it goes. If you majored in the humanities you have to make a living somehow. Not to be racist, but what really bothers me is the amen chorus of white liberals who deconstruct and denounce all manner of cultural production for its lack of “diversity”, but who live lives as populated by white people as the protagonist of Boyhood. As it happens I have a lot of white friends, and sometimes on Facebook you see wedding photos. Most of my friends are liberal, though not all, and one thing that is salient is that these wedding parties and attendees are mighty white. Even in California, where half the population is non-Hispanic white, good white liberals seem to be inviting only white people to their seminal life events.

So I’m proposing the “wedding test” to see if you really walk the walk on diversity and all that. You don’t have to marry someone of another race, I know that’s going too far for most people (recalling the Reihan Salam column in Slate where comments analogized same race preference to sexual orientation). But if diversity is really something you value, presumably that will be reflected in the few hundred people you invite to your wedding party. Change starts at home, if you can’t diversify your personal life, perhaps you should get off your high horse about how we need “more diversity in field X.”

 
• Category: Race/Ethnicity • Tags: Race 
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A few weeks ago people were arguing about the utility of the model based clustering packages which produce intuitive bar plots which break down individual and population percentages. To understand the fundamental basis of these packages I’ll refer you to the original Pritchard et al. paper. As you probably know at this point one of the major parameters of the packages is the K value, which refers to the number of populations which are going to be assumed as the constituents of the genetic variation. A key point is that those who use the packages are forcing the variation to fit a particular model. You can take the data for Icelanders, to pick an example, and find K = 100. It will be produce results, but I suspect you’ll intuit that this really isn’t the best model in terms of fitting reality. Similarly, you can take a population of Northern Europeans, West Africans, and East Asians, and set K = 2. This will likely separate the Eurasians from the Africans, as that’s the natural phylogenetic affinity. But K = 3 is probably a better fit to the data. By this, I mean that Northern Europeans and East Asians are not, and have not been for a long time, random mating populations. K = 3 reflects this reality.

So far this is intuitive. Is there a formal way to check this? Yes. A variety. Structure outputs log likelihoods for each K. Admixture gives you cross-validation errors. For a full treatment of how Admixture estimates cross-validation error see Alexander et al. An intuitive way to think about how you should interpret these values is that they are giving you a sense of where you are trying to squeeze too many K’s out of the data set. Admixture’s cross-validation value has a simple interpretation, look for the lowest point on the graph.

Going to back to the HGDP data set I wanted to know where that point on the scale of K’s was. Looking over the populations I assumed more than 5, but likely less than 20. That wide range tells you that I don’t honestly have a good intuition (some distinct populations are going to be hard to separate in pooled data sets because there hasn’t been much time since divergence, or they are not really genetically separate populations).


The first thing I did was prep the HGDP data bit in terms of quality with Plink. I filtered to SNPs with minor allele frequencies greater than 0.05, to get variants which might be informative on the interpopulation scale. Then I removed SNPs which were missing in more than 1% of individuals. Finally, I also LD pruned the SNPs (basically thinning the markers so that I got rid of variants which weren’t adding more information because they were near other SNPs). Additionally I also removed individuals which were very closely related to others in the data set. This resulted in a data set of 1,024 individuals and 116,840 SNPs.

Then I ran Admixture 20 times with default five-fold cross-validation from K = 2 to K = 20. Here’s the result in a scatterplot:

cverrorbig

You can’t see some of the points because the variation in error was so small at the lower K’s. It is clear that a few K’s do not accurately capture the variation in the HGDP data set. To put it different there aren’t four distinct randomly mating populations in the HGDP data set (K = 4).

Here’s a zoom in.

cverrorZoom

These results make it clear there’s a ‘valley’ across the interval K = 11 to K = 16, with the lowest mean cross-validation error at K = 16. Not only does K = 16 have the lowest cross-validation error, but below K = 4 it has the lowest variation in cross-validation error as well. This does not mean that there are 16 natural populations which best defines the world’s genetic variation. For why this is not so I’ll point you to Daniel Falush’s post What did we learn from Rosenberg et al. 2002, actually?, which highlights some other major dependencies of Structure-like model based clustering.

But, a complementary point is that the number of K’s within the data are not arbitrary and subjective. And that’s because human genetic variation exhibits geographic structure consistently across many forms of vizualization and inference. A second more tendentious point I would also like to add is that the new generation of population structure inference methodologies are pointing to the likelihood that human genetic variation did not emerge through isolation by distance dynamics across clinal gradients.

Addendum: I’m merging my 20 runs, starting with K = 16. But that’s going to take time. I’m also running K = 2 to K = 20 with a different data set, which expands beyond the HGDP, with 20 replicates.

 
• Category: Science • Tags: Genomics, HGDP, Race, Structure 
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raceQ8One of the issues that comes up over and over again is the assertion that folk racial categories are totally useless in terms of taxonomic utility. This is just plain false. Obviously “folk” anything is usually inferior to a scientific form of analysis, but often they are better than nothing. And so it is with folk racial categories. The dichotomy between white European and non-European in a racial sense is a rather new feature of Western history due to the peak of white supremacy ~1900 A.D. The division has persisted as paradigmatic in a particular type of Left-wing post-colonial type common on college campuses. But a rough & ready understanding of human populations as divided on a continental and ecological basis is as old as the ancient Egyptians, who perceived differences in populations in a color coded sense (e.g., they were red, West Asians were yellow, Nubians were black, etc.). The ancient Greeks were even sophisticated enough to distinguish the phenotypes of North and South Indians (the former rather like Egyptians, the latter more similar to Ethiopians except in the texture of their hair).

But I need not appeal to ancient history. In 2002 a group out of Stanford published Categorization of humans in biomedical research: genes, race and disease. They plainly asserted:

A major discussion has arisen recently regarding optimal strategies for categorizing humans, especially in the United States, for the purpose of biomedical research, both etiologic and pharmaceutical. Clearly it is important to know whether particular individuals within the population are more susceptible to particular diseases or most likely to benefit from certain therapeutic interventions. The focus of the dialogue has been the relative merit of the concept of ‘race’ or ‘ethnicity’, especially from the genetic perspective. For example, a recent editorial in the New England Journal of Medicine [1] claimed that “race is biologically meaningless” and warned that “instruction in medical genetics should emphasize the fallacy of race as a scientific concept and the dangers inherent in practicing race-based medicine.” In support of this perspective, a recent article in Nature Genetics [2] purported to find that “commonly used ethnic labels are both insufficient and inaccurate representations of inferred genetic clusters.” Furthermore, a supporting editorial in the same issue [3] concluded that “population clusters identified by genotype analysis seem to be more informative than those identified by skin color or self-declaration of ‘race’.” These conclusions seem consistent with the claim that “there is no biological basis for ‘race’” [3] and that “the myth of major genetic differences across ‘races’ is nonetheless worth dismissing with genetic evidence” [4]. Of course, the use of the term “major” leaves the door open for possible differences but a priori limits any potential significance of such differences.

In our view, much of this discussion does not derive from an objective scientific perspective. This is understandable, given both historic and current inequities based on perceived racial or ethnic identities, both in the US and around the world, and the resulting sensitivities in such debates. Nonetheless, we demonstrate here that from both an objective and scientific (genetic and epidemiologic) perspective there is great validity in racial/ethnic self-categorizations, both from the research and public policy points of view.

The first author of the above paper was interviewed by Ta-Nehisi Coates last year.

 
• Category: Race/Ethnicity, Science • Tags: Race 
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41BYpEQumNL._SY344_BO1,204,203,200_ Of late people have been leaving off-topic comments early on in threads. I don’t understand why this is happening, as I always post (or try to) an “Open Thread” every Sunday. I don’t post enough at this point where this isn’t usually on the front page, or near it. Please make use of it! From now on I’m going to just not publish off-topic comments because it seems a little rude that people don’t post them in “Open Thread”. I see the beginning of all comments as I have to approve them manually right now, so there’s no reason to hijack another thread. It just annoys me, and probably makes me less likely to actually respond.

A lot of these off-topic comments lately have been about Nick Wade’s new book, A Troublesome Inheritance: Genes, Race and Human History. The reason I haven’t reviewed it is that I haven’t read it, and the reason I haven’t read it is that I don’t have the time. It is easy for me to read an article or paper, and then put up a quick response. Or perhaps one of my own analyses of data sets I have lying around. To read a book and then review it takes a lot more time. Second, there have already been a lot of reactions on the book, so I don’t see what I would have to add. Nick actually told me around four years ago that he was thinking about writing this book, so its appearance did not surprise me at all, though the mainstream reaction seems more muted than I would have guessed.


Some general points though. First, the modern American consensus that race is a social construct is true but trivial. It’s true because a de facto race such as “Latinos/Hispanics” were created in the 1960s by the American government and elite for purposes of implementing public policies such as affirmative action. Obviously this is a classic case of a social construct, as the quasi-racial category is based upon social, not biological, factors (Latinos/Hispanic can explicitly be of any race, though implicitly it’s transformed into a non-white class in the United States). A group like “black Americans” ranges from people with considerably less than 50% African ancestry to more than 90% African ancestry (though almost always black Americans who are not immigrants from Africa or first generation offspring of those immigrants have some segments of European ancestry). The problem is that people move from this non-controversial point, that some racial categories are social constructs, to the assertion that all racial categories are social constructs, and that phylogenetic clustering of human populations is irrelevant or impossible. It is not irrelevant, or impossible. Human populations vary, and that variation matters. Human populations have specific historical backgrounds, and phylogenetics can capture that history through methods of inference.

Moving from phylogenetics to population genetics, there is the question about whether population-genetic dynamics such as migration, drift, mutation, and selection have resulted in significant variation across human populations. Yes, they have. Human populations have significant functional differences which track regional adaptation, and also correlate to an extent with racial clusters, and phylogenetic history. The details here are empirical, and you need to take into account what we’re learning about human demographic history to make sense of how and when adaptation occurred. This where the controversial aspects of Wade’s book come in, because he argues that there are behavioral differences across populations due to distinctive evolutionary histories. Complex traits like behavior are often subject to numerous upstream causal variations, so untying the knot is not easy.

But I don’t think it’s impossible, and I suspect there are indeed behavioral differences between populations due to genetic differences between populations. The problem is that we haven’t really done enough research in this area to talk about the genetics of it in anything more than a speculative fashion, and complex traits which are less controversial and more tractable than behavior or cognition, such as height, have already presented difficulties for researchers despite extensive devotion of resources. But the truth of the matter in this area will come out at some point. As it is right now, it does indeed seem that the small differences in height between Northern and Southern Europeans are due at least in part to differences in frequencies of alleles which are known to influence height.

 
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Conservatives sometimes like to recycle this picture from the 2012 Obama headquarters as the victory results were coming in. What one can see is the surfeit of pallor, not that there’s anything wrong with that as such. Except that many Left-liberals make the Right’s lack of diversity ipso facto evidence of racial animus. But many liberal/progressive individuals also live in a rather white world. Not that this hasn’t been noted on occasion. But you still have the background assumption which motivated this notorious Chris Hayes quote:

It is undeniably the case that racist Americans are almost entirely in one political coalition and not the other.

I think the underlying model is simple. Since white conservatives are racist, broadly construed, the whiteness of their milieu adds to the confidence of the hypothesis of their racism. In contrast, since white liberals are not racist, the whiteness of their milieu is irrelevant. More precisely, the lack of diversity in some progressive segments of society is not highlighted to the same extent that it would be in conservative segments of society.

The reality is that both liberals and conservatives among whites engage in self-segregation (as do people of all races, religions, etc., more or less!). This despite a Left-Right convergence on issues such as “diversity” and anti-racism. To make this more quantitative I decided to look at the RACHOME variable in the General Social Survey. Asked between 1974 and 2006 it is as follows: “During the last few years, has anyone in your family brought a friend who was a (negro/black/African-American) home for dinner?” This is a very broad question. Here are the results plotted from ’74 to ’06:


BlackFriendOver

The blue is for white liberals, and the red line for white conservatives. You can see that over the past 30 years more and more white people of all ideologies can say that they’d have a black friend over for dinner in the past few years. But it still remains the fact that ~50% of white liberals and conservatives haven’t had a black friend over for dinner in a span of years. Some of this clearly just due to broader historical segregation. It wouldn’t be surprising if whites in North Dakota didn’t know many black people. On the other hand…there aren’t many people in North Dakota, of any race.

Part of this comes to mind because ProPublica has an article on resegregation in public schools in the South that’s getting a great deal of media attention. My question though is simple: why the focus on the South when the highest indices of segregation of this sort is in the North? The ProPublica piece states that:

In recent years, a new term, apartheid schools—meaning schools whose white population is 1 percent or less, schools like Central—has entered the scholarly lexicon. While most of these schools are in the Northeast and Midwest, some 12 percent of black students in the South and nearly a quarter in Alabama now attend such schools….

The South has a particular history with race, and that is an important history. But the continuous focus on this region of the country is I think driven in part by the reality that the cultural elites, often white progressives, are not keen on shining a light on the segregation which they themselves have passively accepted in their own lives.

seg2000krige In fact the worst segregation of blacks and whites is in major urban areas of the Great Lakes. According to the Census the most segregated cities are Detroit, Milwaukee, New York, Newark, and Chicago. But for some reason there are fewer exposes on how upper middle class, usually white, couples in major “Blue America” urban areas flee racially diverse public schools for the suburbs or private schools. The reasons for these actions are defensible in my opinion, but one should probably admit that these are likely the major causes of resegregation in the South as well. The ProPublica piece itself highlights the importance of class as a driving dynamic, as the black underclass in particular is packed into apartheid schools. History is important, and it shadows us down into the present, but a fixation on racial nature of Southern society with roots in the 19th century misleads in terms of the dynamics driving the 21st century.

This leads me to conclude with my friend Reihan Salam’s piece in Slate, Is It Racist to Date Only People of Your Own Race? Yes. I disagree with Reihan with using the “r-word,” but some of his points are very cogent:

…“Would you strongly prefer to go out with someone of your own skin color/racial background?” I was struck by the not inconsiderable number of people who answered “yes”—including some people I know “in real life,” many of whom are hilariously self-righteous about their enlightened political views.

…Nancy DiTomaso argues that persistent racial inequality in the United States is not solely or even primarily a reflection of racism and discrimination. Rather, it reflects the fact that whites tend to help other whites without ever discriminating against or behaving cruelly toward blacks and other nonwhites. As long as whites tend to dominate prestigious occupations, and as long as they control access to valuable social resources like access to good schools, the fact that whites, like all people, will do more to help family, friends, and acquaintances than strangers will tend to entrench racial inequality, provided that white people choose to associate primarily with other whites. DiTomaso observes that while Americans place very high value on the idea of equal opportunity, virtually all of us seek “unequal opportunity” in our own lives by leveraging our intimate relationships to achieve our goals, including our professional goals. Yet most of us don’t see the help of family and friends as an unfair leg up. This kind of “opportunity hoarding” is accepted as par for the course….

Though the piece begins by talking about dating, it seems to me that the second paragraph quoted above gets to the serious heart of the matter. In our modern day discussion both liberals and conservatives talk about racial justice as if it is a matter of passing effective laws. From the liberal perspective it would be something like affirmative action. From a conservative perspective it might be color-blind laws. But the key assumption in both cases is that modulating the explicit framework of institutions will be effective. But what if they’re not? What if in fact most racial inequality is a function of social-cultural racism, rather than institutional racism? This is not a crazy idea, and goes to why there has been pressure to open up exclusive male-only clubs to women.

But this is not a can of worms most people are open to discussing. Since I’m conservative, and am much more sanguine about racial inequality and the long term prospect of an egalitarian society generally, I’ve been on the receiving end of nice and not-so-nice critiques from my liberal friends (i.e., almost all my friends). And yet since these are my friends I know something of their lives, and the sting of their self-righteousness tends to diminish strongly when I point out to them that despite the diversity of their demographic locale it is quite clear that they exhibit strong tendencies to assort with other white people in their personal life (as friends, or more than friends). I’m not particularly judgmental of this sort of thing, I have mostly white friends as well, but it does suggest to me that talk is talk, and much of the political debate around justice and inequality is more about posturing and signalling than something fundamental to one’s being.

The comments on Reihan’s Slate piece are quite interesting. Presumably this is a mostly liberal magazine with a liberal readership, but it is amusing how defensive many of the respondents are about dating their own kind. E.g., “Is it homophobic to only date people of a different sex?” is a common response. This implies perhaps that it is natural to prefer one’s own race. There is actually some evidence for this position.

Right now we’re having the same old tired arguments about affirmative action. They’ve been rehearsed for a generation, so there’s no real need to even think before speaking. Liberals will talk about the need for a frank discussion about race, which mostly involves agreeing with liberals about all the major points. Conservatives will attempt to co-opt Martin Luther King Jr. and promote the possibility of an outcome of color blindness which is totally at variance with reality. We don’t even know what the end goal is. Is it a society where different races and cultures flourish independently? One where individuals mix freely in a cosmopolitan melting point? Real engagement with the issues is going to be complicated, and entail honest admission of how people are living their lives, not empty gestures toward symbolic rhetoric that has long since gone stale.

 
• Category: Race/Ethnicity • Tags: Race 
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Citation: Moreno-Estrada, Andrés, et al. "Reconstructing the Population Genetic History of the Caribbean." PLoS genetics 9.11 (2013): e1003925.

Citation: Moreno-Estrada, Andrés, et al. “Reconstructing the Population Genetic History of the Caribbean.” PLoS genetics 9.11 (2013): e1003925.

The Chronicle of Higher Education has an article up on the intersection of genomics and sociology, In Research Involving Genome Analysis, Some See a ‘New Racism’. Most of the quotes are from sociologists, which is a problem, because whenever I try and delve into the topic it seems that sociologists don’t actually engage with the latest genomic research, but simply rehash older models which refute naive essentialism which biologists would never find plausible in the first place. But there was an intriguing quote in the piece from Jiannbin Shiao: …The social sciences should replace their biology-based rejection of race “with a version of the feminist distinction between biological sex and socially constructed gender,” he writes. With several co-authors, he has developed a concept called “clines,” adapted from how economists talk about social class, which reflects the continuous nature of human variation while allowing loose clusters to develop, depending on how you zoom into the data.

The paper is The Genomic Challenge to the Social Construction of Race. It is admirable in its attempt to engage in the recent literature. Unlike other sociologists the authors seem to have read publications from the 21st century. I do think it’s strange that they are talking about clines as if it is a new idea, seeing as they cite its long-standing usage in biology. But perhaps it is somehow a novel concept in sociology? That says something about sociology I suppose.

But in an area of research such as genomics citations that are six years old may be out of date. The authors published in the summer of 2012, and no doubt had been working on the paper for a few years before that. I’m pretty sure that Steve Hsu, a former colleague of the first author at the University of Oregon, actually told me about the genesis of this paper in the spring of 2011 when I had coffee with him at Berkeley. The authors state:

The primary tools for identifying population structure have been, in order of emergence, (1) comparisons of predefined populations, (2) the Bayesian clustering approach of the program STRUCTURE developed by Pritchard, Stephens, and Donnelly (2000), and (3) new variations on the classical technique of principal components analysis (Paschou et al. 2007). Although social studies of science continue to criticize the circular research design of the first method (Bolnick 2008; Duster 2006b; Marks 2006), the second and third methods have been preferred among academic researchers for over a decade (Risch et al. 2002; Rosenberg et al. 2002).


It has always been frustrating to me that social scientists who object to any utilization of race in a biological sense presume that everyone must have a typological model in mind. So it is good that the authors understand that model-based (STRUCTURE) and hypothesis-free (PCA) clustering are the norm now. But over the past few years genomics has opened up new avenues of analysis, which make these methods somewhat passe. In particular, admixture analysis using segment assignment gives a much finer grained window into the historical genomic landscape of a population. Additionally, segment analysis also leads me to suggest that a default clinal model may not even be defensible in the near future.

I outlined the thesis in my two earlier posts. In short, I propose that in fact because of the protean nature of human culture our species’ development over the last ~50,000 years has been subject to many expansions and replacements, which only requilibrate toward a clinal gradient through admixture. This shows the problems in rooting a normative world-view on an empirical scientific basis. I’m not being original here, and only need to nod to the is-ought problem and the naturalistic fallacy. If your moral understanding of the world is predicated on empirical claims, you should be willing to update those claims. As it is most people are not so inclined, and will continue to reject those empirical results if they are at variance with their preferences. My own views are well known, science goes where it may, and we only delay the inevitable if we shy away from research that may cause us discomfort. Let me quote two evolutionary geneticists on this issue. First, James F. Crow on the study of intelligence and genetics:

I hope that such questions can be approached with the same objectivity as that when we study inheritance of bristle number in Drosophila, but I don’t expect it soon. There are too many strongly held opinions. I thought Lahn had a clever idea in thinking that the normal alleles of head-reducing mutants might be responsible for evolution of larger heads in human ancestry. Likewise, I think that Cochran et al. are fully entitled to consider the reasons for Jewish intelligence and I found their arguments interesting. In my view it is wrong to say that research in this area — assuming it is well done — is out of order. I feel strongly that we should not discourage a line of research because someone might not like a possible outcome.

Now, A. W. F. Edwards, one of Fisher’s last students:

A proper analysis of human data reveals a substantial amount of information about genetic differences. What use, if any, one makes of it is quite another matter. But it is a dangerous mistake to premise the moral equality of human beings on biological similarity because dissimilarity, once revealed, then becomes an argument for moral inequality. One is reminded of Fisher’s remark in Statistical Methods and Scientific Inference… “that the best causes tend to attract to their support the worst arguments, which seems to be equally true in the intellectual and in the moral sense.”

Certainly over the years I have encountered many people who have come to the conclusion that the standard sociological arguments about the fictional nature of racial categories are false, and derive from the caricature that crude racist positions are tenable and correct, and defensible on normative grounds. I have to say that part of this is due to the appeal to science by those who defend liberal democratic values, when that science may not stand up to deeper inspection. Basing your ought on is is not always wrongheaded in my opinion, but you should be very clear on what you are doing.

 
• Category: Science • Tags: Race 
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250px-Indig1 One of the most interesting results in the preprint on ancient European genetics (or more accurately, the ethnogenesis of Europeans in a genetic sense) is the fact that the ~8,000 year old hunter-gatherer sample from Luxembourg had a GG genotype on the SLC24A5 locus. Actually, interesting isn’t the right word, shock, and frankly a little skepticism is more precise. The reason for my reflexive incredulity is that the GG genotype is very much the minor variant in Western Eurasia, and extremely rare among unadmixed Europeans. Europeans have such a high fraction of the A allele that some population genetic statistics to test for selection at a locus are not viable, because there’s not enough variation segregating in that region. This allele also is present outside of Europe, with the A allele being the major variant in South Asians, albeit at a lower fraction, verging on ~50% or less in some South Indian groups. Yet it is not entirely implausible that this allele only swept to fixation over the past 8,000 years in Europe looking at the genomic features* of the region in which it is embedded.

I want to make more concrete why this result is a pretty big deal. If you look at the 1000 Genomes data you have results for British, Finnish, Tuscan, and Spanish individuals, as well as a well characterized sample of white Utahans of Northwest European heritage. There is also a less well characterized pooled data set of “European Americans.” Here are the genotype counts by population:

Population AA AG GG
Utah white 85 0 0
British 89 0 0
Finnish 91 2 0
Tuscan 97 1 0
Spanish 14 0 0
European American 4256 40 1

Yesterday on Twitter I suggested that I’d want at least 10,000 individuals of unadmixed Northern European ancestry before I might take a bet that I’d find someone with a GG genotype. I don’t think I was exaggerating. The sample size might be one, but the fact that the individual was homozygous for GG implies to me that the G allele was present at a far higher fraction in Northern Europe 8,000 years ago than today. In contrast the LBK farmer individual was AA on SLC24A5. Why this matters functionally is that no matter how you look at it, when comparing Europeans and dark skinned populations (e.g., Africans, South Indians, and Australasians) this locus is the one that explains the highest proportion of the variation on pigmentation of any gene. Comparing simply people of African ancestry and Europeans the variation at this gene accounts for on the order of ~1/3 of the difference.** I myself have the “European” AA genotype, with most of my other large effect loci being of the “dark” correlated alleles. The pigmentation difference between a Sub-Saharan African and myself is probably accounted for just by this locus alone. But a twist on this story is that the hunter-gatherer also exhibited the genotype associated with blue eyes in Europeans. In contrast, the farmer genotype was the one not correlated with blue eyes. On another locus which is not quite fixed for a derived light encoding variant, but very close in Europeans (and found in much lower proportions in other West Eurasians), SLC45A2, it looks as if both the hunter-gatherer and the farmer carry the modal European form.

220px-Lucy_Merriam Rather that squeezing too much more out of a few samples, I want to posit that these results increase the plausibility that the suite of genetic variants across many loci which are often diagnostic of the complexion of Northern Europeans are a function of a combination of admixture and then selection within the resultant Northwest European lineages. It seems plausible that independent selection events were occurring across these groups, and with admixture more novel variants were present in the combined population which allowed for a skew even further along the phenotypic continuum, toward the physiological limit (at least for non-albinos). Though it looks like the majority of the ancestry of Northern Europeans, especially populations around the coastal East Baltic region, derive from hunter-gatherer groups indigenous to the continent (i.e., pre-Holocene), if they were not fixed for the derived variant on SLC24A5 it seems implausible that these ur-Europeans were defined by the rosy complexions which are archetypical for Northern Europeans . This is part of the broader picture whereby the phenotypically salient population clusters we see around us today, as if they are Platonic ideals of underlying racial forms, may themselves be phenomena distinctive to the Holocene .

* A large correlated block of markers which seem to have risen in frequency recently and rapidly within the population.

** Northeast Asians have their own distinct mutations which confer light skin.

 
• Category: Science • Tags: Pigmentation, Population Structure, Race 
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Goebbels, Nordic superman! Credit: Bundesarchiv, Bild

Goebbels, Nordic superman!
Credit:, Bundesarchiv, Bild

Many of you probably know about Dave Chappelle’s black white supremacist sketch (NSFW video!), though fewer are aware of Leo Felton, a white supremacist (ex, after he was outed) with a black father (a less tragic outcome than Dan Burros, the Jewish American Nazi). I know, these sound like they’re out of South Park episodes, though the last two are actually not fictional. But now the media is exploding with news that a DNA test has suggested that a notorious white supremacist is 14 percent black. The same one who was recently profiled in The New York Times promoting a separatist racial vision in a small North Dakota town. I’ll be honest and admit that I don’t think that these results will hold up. (though personally I would think it was rich and very funny if they did, just like everyone else).

Credit: ScottH

Credit: ScottH

The reason is the chart to the left. It’s from 23andMe‘s data set. Out of their ~100,000 white American individuals tested, ~5% have any evidence of African ancestry. Of those, you see the distribution of results. If Craig Cobb, the white supremacist, is ~14% Sub-Saharan African, he’s in the less than 0.1% of white Americans with this sort of pattern. If he was a Latin American white, or a identified white person of Arab ancestry, I’d be willing to accept the results as plausible on the face of it. But the reality is that European Americans with relatively well documented histories usually do not have a high probability of having African ancestry. And if they do, 14% is a great deal. I have seen this among my friends (or more honestly, 5-10%, which is not far off), but that was due to a cryptic (though somewhat known within the family) non-paternity event.

The media isn’t consistent about which firm tested Craig Cobb, so I’m not going to make accusations specifically, but he says he’s getting other tests done, and he’ll release the results. I’ll be curious to see the raw results. To me this is reminiscent of the constant Facebook shares I get from the Daily Currant from friends who confuse satire for reality because of their biases (not to say those biases are unfounded or not). Just because the story is awesome does not mean we should set skepticism to the side, and not evaluate the probability of alternative outcomes, given what we know prior.

Related: Has anyone followed up the old story that James Watson was part black? The timing was a little suspicious to me.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Race 
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The New York Times recently put up a piece, Has ‘Caucasian’ Lost Its Meaning? Much of the analysis in the article has too much of a feeling of ethnographic ‘close reading’, but I still am excited that the middle-brow journal of record has started to weigh in on the ridiculousness of the whole situation. I’ve been arguing that people should stop using “Caucasian” when they mean white or European for years, because the use of the term in this manner has led to farcical but common instances of semantic muddle such as the below exchange:

****Whate race do GEORGIAN people belong to***? – well if you are georgian or armenian and you go to other country, it is very hard for people to believe that you are white, everyone thinks either you are hispanic or mix so i was wondering what is the name of the race georgians.armenian are?

[One of the answers] As more and more people move around and settle in different locations, it’s becoming more and more difficult to ‘racially’ identify people by regions. Now if it were a few hundred years ago, I would have said Caucasian…but then as time has gone by Middle Eastern seems more appropriate…

Obviously, unlike a few hundred years ago, Georgians no longer reside in the Caucasus mountains. Nor are they any longer the archetype of West Eurasian populations. I am not going to have one of those inane discussions about whether Georgians really are white, though any reader who believes such a thing is invited to start referring to Stalin as the Soviet Union’s only head of state of color in the future. My primary issue with the modern American usage of the term is two-fold:

- Using the term Caucasian to refer to white Europeans and their descendants makes as much sense as referring to all East Asians as “Chinese.” There actually are real Caucasian people, who are no longer exotic people in an out-of-the-way corner of the world. It would be nice if we could spare the less intelligent from committing their common acts of assault against the fabric of reality by wondering whether Georgians were Caucasian or Middle Eastern (not or in the logical sense of either, but in the colloquial sense of one or the other in an exclusive manner) in the future.

- Substituting “Caucasian” for “white” is also for some reason a bizarre way to be politically correct and pretentious. The irony is that the pretentious people who use the term Caucasian only signal their banal conformity to substantively ludicrous mores which they lack the capacity or will to reflect upon. Looking through The New York Times archives it is clear that the term Caucasian has become more and more just a substitute for the term white, especially after the collapse of the Soviet Union and earlier the death of Stalin. Just another case I suppose of the paper exposing its substantive shallowness when moving beyond pure description and reportage.

Sure enough Google Ngrams also confirms my hunch that the usage of Caucasian is on the rise. While the old racial terms Caucasoid, Mongoloid, and Negroid have declined in frequency over the past generation, Caucasian has experienced a renaissance since the 1980s:

Finally, my personal experience is that human population geneticists do not use the term “Caucasian” except when they are talking about Armenians and Georgians and other Caucasian people, while biomedical geneticists do use the term “Caucasian” in its wrong-headed pretentious fashion. I don’t think this is because population geneticists are less pretentious than biomedical researchers (on the contrary!). Rather, population geneticists have a tendency toward thinking deeply about populations…so the superficiality of the term becomes clear. Second, in the United States biomedical research is encased in such a level of regulatory bureaucracy that I would not be surprised if the common usage of “Caucasian” on forms resulted in the spread of the term as a matter of course. I know, for example, that some biomedical research projects have used standard US Census race terms, and reported the unsurprising result that the “Asian” category is less than useful because it aggregates South and East Asians, who are not genetically very close. Considering what a big deal population stratification is in case-control genome-wide association projects whose aims are biomedical, the power of cultural constructs which are ridiculous to interpose themselves into scientific discourse strikes me as either depressing, or unfortunately, to be expected.

In any case, ire and excoriation seems the only long term solution to these sorts of reality obscuring memes.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Caucasian, Race 
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Prompted by my post Ta-Nehisi Coates reached out to Neil Risch for clarification on the nature (or lack thereof) of human races. All for the good. The interview is wide ranging, and I recommend you check it out. Read the comments too! Very enlightening (take that however you want).

When it comes to this debate I have focused on the issue of population substructure, or race. The reason is simple. Due to Lewontin’s Fallacy it is widely understood among the “well informed general public” that “biology has disproved race.” Actually, this is a disputable assertion. For a non-crank evolutionary biologist who is willing to defend the race concept for humans, see Jerry Coyne. When you move away from the term “race,” then you obtain even more support from biologists for the proposition that population structure matters. For example, a paper in PLoS GENETICS which came out last week: Analysis of the Genetic Basis of Disease in the Context of Worldwide Human Relationships and Migration. In other words, it is useful to understand the genetic relationships of populations, and individual population identity, because traits correlate with population history. Barring total omniscience population history will always probably matter to some extent, because population history influences suites of traits. If nothing in evolutionary biology makes sense except in light of phylogeny, much of human biology is illuminated by phylogeny.

But that doesn’t speak to the real third rail, intelligence. Very few people are offended by the idea of the correlation between lactase persistence and particular populations. Neil Risch says in the interview with Coates:

One last question. Your paper on assessing genetic contributions to phenotype, seemed skeptical that we would ever tease out a group-wide genetic component when looking at things like cognitive skills or personality disposition. Am I reading that right? Are “intelligence” and “disposition” just too complicated?

Joanna Mountain and I tried to explain this in our Nature Genetics paper on group differences. It is very challenging to assign causes to group differences. As far as genetics goes, if you have identified a particular gene which clearly influences a trait, and the frequency of that gene differs between populations, that would be pretty good evidence. But traits like “intelligence” or other behaviors (at least in the normal range), to the extent they are genetic, are “polygenic.” That means no single genes have large effects — there are many genes involved, each with a very small effect. Such gene effects are difficult if not impossible to find. The problem in assessing group differences is the confounding between genetic and social/cultural factors. If you had individuals who are genetically one thing but socially another, you might be able to tease it apart, but that is generally not the case.

In our paper, we tried to show that a trait can appear to have high “genetic heritability” in any particular population, but the explanation for a group difference for that trait could be either entirely genetic or entirely environmental or some combination in between.

So, in my view, at this point, any comment about the etiology of group differences, for “intelligence” or anything else, in the absence of specific identified genes (or environmental factors, for that matter), is speculation.

In response to this commenter Biologist states (note, I know who this is, and they are a biologist!):

Risch writes: “…the explanation for a group difference for that trait could be either entirely genetic or entirely environmental or some combination in between. … So, in my view, at this point, any comment about the etiology of group differences, for “intelligence” or anything else, in the absence of specific identified genes (or environmental factors, for that matter), is speculation.”

This is essentially correct. The quality of available evidence on which to estimate the contribution of genetic versus environmental factors to group differences in cognitive ability scores is quite poor by biomedical research standards — maybe more in line with standards for social science (I’m only half joking).

In light of that, one is forced fall back on to one’s priors. Without trying to speak for Risch, it is generally considered appropriate to adopt a uniform prior in the absence of other evidence. Under a uniform prior, “…the explanation for a group difference for that trait could be either entirely genetic or entirely environmental or some combination in between.” Maybe Risch would propose a different prior.

In fact, the uniform prior says that there’s a 25% chance that the explanation is 0% to 25% genetic, a 50% change that the explanation is 25% to 75% genetic, and a 25% chance that the explanation is 75% to 100% genetic. Obviously many people who write about this topic do not adopt a uniform prior. [my emphasis -Razib]

As Risch observes above intelligence is highly polygenic. There’s a fair amount of genomic evidence for this now. In other words the likelihood is not high that we will be able to account for the differential distribution of IQ between any two populations by differences in allele frequencies. Even if we do find the allelic differences, they’ll account for far too little of the variation in the trait. But there is another way we can get at the issues. Others have pointed out exactly how we can get more clarity on the race and IQ question before, so I’m not being original. And since I suspect that within the next decade this sort of analysis will likely be performed at some point somewhere because the methods are so simple, I might as well be explicit about it.

Let’s focus on the black-white case in the American context. On intelligence tests the average black American scores a bit less than 1 standard deviation below the average white American. As I’ve observed before the average black American is ~20% European, but there is variation around this value. Because the admixture is relatively recent (median ~150 years before the present) there is a wide range across the population of ancestry. In fact, the admixture is recent enough that siblings may even differ in the amount of European ancestry on a genomic level. An additional issue which is of relevance is that the correlation between ancestry and physical appearance in mixed populations is modest. By this, I mean that there are many individuals who are more European in ancestry in the African American population who have darker skins and more African features than those who have less European ancestry. Obviously on average more European ancestry predicts a more European appearance, but this is true only on average. There are many exceptions to this trend.

At this point many of you should have anticipated where I’m going. If the gap between blacks and whites on psychometric tests is totally driven by genetic differences between Africans and Europeans, then the gap should be obvious between pools of individuals of varying levels of European ancestry within the African American population. It seems unlikely that it would be that simple (i.e., all driven by genes without any sensitivity to environmental inputs or context). Therefore I suspect some design where you compare siblings would be more informative.

In a model where all of the between group differences are due to environmental inputs then genomic ancestry by geography within family should add little in terms of prediction of the phenotype. More plainly, when accounting for other variables which might correlate with ancestry (e.g., skin color), how African or European a sibling is should not influence outcomes on psychometric tests when looking at large cohorts of sibling pairs if those differences track nothing more than social construction/perception of race. If on the other hand there are many alleles of small effect distributed throughout the genome correlated with geographic ancestry which affect the final phenotype then adding ancestry as an independent variable into the model should be informative. This sort of indirect inference has already been performed with a character similar in genetic architecture to intelligence: height. Researchers have found that African Pygmies with more non-Pygmy ancestry are taller.

Ultimately I say that this issue might semi-resolve, because I think a hereditarian position in terms of group differences is not going to be tenable if the correlations with ancestry do not run in the direction expected within admixed populations. This sort of model is relatively straightforward in its predictions, and appeals to parsimony. Trying to salvage it with non-additive genetic variance is going to complicate matters. In contrast, those who champion the opposite position often dispute the very characterization of intelligence as a trait in the first place, so I presume that they would still exhibit skepticism if there was a correlation between genomic ancestry and the trait.

Addendum: I want to be clear: with the widespread availability of data sets and crappy security of said data sets this analysis is probably a few SQL joins away in 10 years.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Genetics, I.Q., Intelligence, Psychology, Race 
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My own inclination has been to not get bogged down in the latest race and IQ controversy because I don’t have that much time, and the core readership here is probably not going to get any new information from me, since this is not an area of hot novel research. But that doesn’t mean the rest of the world isn’t talking, and I think perhaps it might be useful for people if I stepped a bit into this discussion between Andrew Sullivan and Ta-Nehisi Coates specifically. My primary concern is that here we have two literary intellectuals arguing about a complex topic which spans the humanities and the sciences. Ta-Nehisi, as one who studies history, feels confident that he can dismiss the utility of racial population structure categorization because as he says, “no coherent, fixed definition of race actually exists.” I am actually more of a history guy than a math guy, not because I love history more than math, but because I am not very good at math. And I’ve even read books such as The Rise and Fall of the Caucasian Race and The History of White People (as well as biographies of older racial theorists, such as Madison Grant). So I am not entirely ignorant of Ta-Nehisi’s bailiwick, but, I think it would be prudent for the hoarders of old texts to become a touch more familiar with the crisp formalities of the natural sciences.


In his posts on this topic Ta-Nehisi repeatedly points to the real diversity in physical type and ancestry among African Americans, despite acknowledging implicitly the shared preponderant history. But today with genomic methods we have a rather better idea of the distribution of ancestry among African Americans. The above plot is from Characterizing the admixed African ancestry of African Americans, a 2009 paper with 94 Africans of diverse geographic origins, 136 African Americans, and 38 European Americans. They looked at 450,000 genetic variants (SNPs) per person (there are somewhat more than 10 million SNPs in the human genome). Obviously individuals and populations exhibit genetic relationships to each other contingent upon the patterns of the variation of base pairs (A, C, G, and T) across the genomes of individuals, but there’s no reasonable way to comprehend this “by eye” when you’re talking about hundreds of thousands of markers. The authors used two simple methods to infer clustering within the data set.

First, you see a PCA plot. This method is one where the independent dimensions of variation within the data set of the markers are pulled out. They are rank ordered in terms of how much variation they can explain (dimension 1 by convention explains the most, dimension 2 explains the second most, and so forth). Each dimension can be thought of has having a value proportional to its explanatory power. Each individual then has a value position on the dimension, dependent on how that individual relates to the others. When you take multiple dimensions and transpose the data geometrically you quickly see population structure fall out of the data set. Notice above that the first dimension of variation (PC1) separates the Europeans from all the African populations. The second dimension of variation (PC2) separates the hunter-gatherer populations of Africa from the agriculturalists. While the Mandenka are from Senegal, the Yoruba are from Nigeria, at opposite ends of what is traditionally termed West Africa. This was the presumed source of most of the African slaves who arrived in the United States. Once these slaves came to the United States some of then had children with white Americans. It turns out that the average African ancestral contribution to to African Americans is ~80%, with the balance being mostly European (there is some Native American, but not much). In fact this is very close to the estimates which were produced by genealogists. The concordance of these methods is reassuring, since the underlying phenomena is the same.

Notice that on the PCA plot no African American falls in the Mandenka-Yoruba cluster. That is because almost no African American whose ancestors are not recent immigrants from Africa lack white ancestry. This is entirely reasonable when you consider that the vast majority of their ancestors were resident in the colonies before the Revolutionary War. Admixture events would have percolated throughout the genealogical tree in subsequent generations. The African Americans are distributed almost perfectly along a line between the West African populations and the European Americans. Observe that the density seems to decrease as you approach the European American cluster.

Now we can move to the second visualization technique. While the PCA does not posit any hypothesis of population structure (it just “fell out” of the genetic variation due to the shared history of some individuals via their common ancestors), the second method is “model based,” in that the authors posited seven ancestral populations to match the seven populations which African Americans may be derived from. In a way this is rigging the game; if you force the method to squeeze out particular numbers of populations it may act strangely. But in this case we have prior expectations, so this number of populations is not unreasonable. Above each bar plot represents an African American individual, with each fraction of shading an ancestral element. The results from the PCA are reproduced nearly perfectly by this differing method. The average ancestral quantum of African heritage in this sample is ~80%. And, you see more cleanly the variation in European ancestry among African Americans. Less than 10% of African Americans are like Barack Obama, at least 50% (or more) of European ancestry. The African ancestry excludes the hunter-gatherer populations which is reasonable since the slaves were from the Congo in the east (where some were Bantu) as far as Senegal in the west.

The first black head of the NAACP

Ta-Nehisi has used an imagine of Walter White, the first African American head of the NAACP, to illustrate the pliability of the black identity. It certainly shows that there are no fixed definitions of race which are particularly useful. But that is a misconception of biological science, which is rife with exceptions and boundary conditions, and characterized by an instrumental perspective. The data above suggests that self-identified African Americans are characterized by some African ancestry, but over 90% are more than 50% African in ancestry. Walter White, who had five black great great great grandparents and 27 white ones, was almost certainly less than 20% African in ancestry. There are such people even today, but they are not typical, and do not disprove the reality that African Americans are predominantly of African ancestry.

From a scientific perspective in biology there are not ultimate and fundamental taxonomic facts. There are simply useful ideas and concepts to illustrate and explore the objective phenomena of the natural world. The Species Concepts debate shows us this reality well, as even species can be tendentious. But the debate often shakes out along disciplinary lines. Many more ecological scientists seem to be taken by the ecological species concept, while evolutionary geneticists are more keen on the biological species concept. That is because they are choosing the framework most useful for their ends. There is nothing “Post Modern” in this in that it denies reality. Rather, we are disputing the ideas which we use to capture the essence of real phenomena in compact semantic relations suitable for symbolic representation (whether with math or language).

Prior to the modern systematic era of biology humans did attempt to classify themselves. Generally they looked at a few informative features. For example the Chinese referred to both South and Southeast Asians as “black,” not because they thought they were African, but because they had brown or dark brown skins. Similarly, Arab ethnographers differentiated between ruddy peoples to the north, black ones to the south, and black ones to the east (Indians). And so on. This is almost certainly an elaboration of our innate cognitive ‘folk biology.’ By this, I mean that we as humans tend to classify organisms. Why this is adaptive is trivially obvious. When humans meet new organisms which resemble those which they have familiarity with prior, they simply reformulate the novel creatures as variants of the familiar ones. For example the Tasmanian Tiger was no tiger. It was not even a placental mammal. But through convergent evolution it resembled placental carnivores. Analogously, when Europeans first met the straight haired brown skinned native peoples of the New World they termed them “Indians,” a straight haired brown skinned population of the Old World. When they met the very dark and kinky haired peoples of the western Pacific they assumed they were some relation to Africans, and these became “Melanesians” (which means “black islanders”).

A second component of human nature which Coates alludes to is our tendency to cohere into groups with narratives of internal identity set apart from the Other. In the pre-modern world these inter-group cleavages would be marked by accent, dress, and tattoos. In the early modern world they would be correlated with religion or nationality. The dynamic at issue here is that extremely genetically close populations which would be indistinguishable naked had to generate salient cultural markers. In the case of the ancient Hebrews one could argue that circumcision was exactly the sort of marker which would persist even when naked!* This does not mean that there were no detectable genetic differences between adjacent small scale societies; there are after all detectable genetic differences across European villages today. But for particular technical evolutionary reasons (far more within group variance than between group variance in regards to genetics) it is likely that for inter-group competition cultural forces reigned supreme over biology, and were determinative of identity.

Both of these parameters are from our deep history as a species characterized by life as hunter-gatherers in bands. The next force is more recent, and historically contingent. As I suggested above non-European and pre-modern peoples had a vague conception of race on the continental scale. The Classical Greeks even distinguished he various brown peoples, the Egyptians and the Indians of the north, and black peoples, the Ethiopians and the Indians of the south. The fact that the initial explorers who arrived in the New World labeled the indigenous people Indians, and not Chinese or Africans, shows an awareness of global diversity (in contrast, the British referred to the Australian Aboriginals as blacks). When the British first arrived in India as supplicants to the Great Mughal they differentiated between the diverse races of the subcontinent. The black and brown natives, and a portion of the elites who were white (West Asian Persians and Turks).

This changed over the centuries, and after 1800 the age of European supremacy and the rise of systematic science produced the sort of racial nationalism which serves as the backdrop to our understanding of race more generally. Whereas the pre-modern folk biological taxonomies were coarse, but generally accurate up to a point, the age of white supremacy produced a somewhat schizophrenic science of precision and exaggeration. By this, I mean that the attempt to be formally scientific resulted in a plethora of categorizations and grades of hierarchy. But, the reality of white supremacy generated a taxonomy of dominion, where all the races of color were aggregated into an amorphous whole. Perhaps these two countervailing tendencies explains the juxtaposition of quasi-fixed racial characters with a bizarrely elastic definition of the Other, the non-white. Few moderns agree with Lothrop Stoddard’s The Rising Tide of Color Against White World-Supremacy, but many implicitly accept the framework of whites and a coalition of “people of color.”

So there you have it. An underlying biological reality which is a reflection of deep history. It may not be real or factual, but it is consistent and coherent. Then there are innate faculties which lead us toward categorization of humans into various kinds, for deeply adaptive purposes. Finally, there are historically contingent events which warp our perception of categories so as to fit into power relations in a straightforward sense. But wait, there’s more!

Diabetes risk higher in African Americans with more African ancestry, link

The biological aspect above focused on ancestry and history. But this is not academic detail. The history of a population affects it genome, and its genome effects the nature of its traits and diseases. Because of differences across populations statistical geneticists with medical aims routinely restrict their data set to individuals of one population. And, within groups like African Americans which are admixed there is variation in disease risk by genomic fraction. Though an individual with 60 percent African ancestry may feel and say they are no more or no less African American than someone who is 80 percent African in ancestry, there are differences in disease susceptibilities.

There is no Platonic sense where there are perfect categories with ideal uses. Rather, we muddle on, making usage of heuristics and frameworks which are serviceable for the moment. We lose our way when we ignore the multi-textured nature of the issues.

* Though many of the neighboring peoples practiced circumcision, so this is more of an apocryphal illustration than a real instance of functional traits on a cultural level in societies.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Race/Ethnicity, Science • Tags: Classic, Genetics, Genomics, Race 
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There’s an excellent paper up at Cell right now, Modeling Recent Human Evolution in Mice by Expression of a Selected EDAR Variant. It synthesizes genomics, computational modeling, as well as the effective execution of mouse models to explore non-pathological phenotypic variation in humans. It was likely due the last element that this paper, which pushes the boundary on human evolutionary genomics, found its way to Cell (and the “impact factor” of course).

The focus here is on EDAR, a locus you may have heard of before. By fiddling with the EDAR locus researchers had earlier created “Asian mice.” More specifically, mice which exhibit a set of phenotypes which are known to distinguish East Asians from other populations, specifically around hair form and skin gland development. More generally EDAR is implicated in development of ectodermal tissues. That’s a very broad purview, so it isn’t surprising that modifying this locus results in a host of phenotypic changes. The figure above illustrates the modern distribution of the mutation which is found in East Asians in HGDP populations.

One thing to note is that the derived East Asian form of EDAR is found in Amerindian populations which certainly diverged from East Asians > 10,000 years before the present (more likely 15-20,000 years before the present). The two populations in West Eurasia where you find the derived East Asian EDAR variant are Hazaras and Uyghurs, both likely the products of recent admixture between East and West Eurasian populations. In Melanesia the EDAR frequency is correlated with Austronesian admixture. Not on the map, but also known, is that the Munda (Austro-Asiatic) tribal populations of South Asia also have low, but non-trivial, frequencies of East Asian EDAR. In this they are exceptional among South Asian groups without recent East Asian admixture. This lends credence to the idea that the Munda are descendants in part of Austro-Asiatic peoples intrusive from Southeast Asia, where most Austro-Asiatic languages are present.

And yet one thing that jumps out at me is that there is no East Asian EDAR in European populations, even in Russians. I am a bit confused by this result, because of the possibility of Siberian-affiliated population admixture with Europeans within the last 10,000 years, as adduced by several researchers (this is not an obscure result, it manifests in TreeMix repeatedly). The second figure shows the inferred region from which the East Asian EDAR haplotype expanded over the past 30,000 years. The authors utilized millions of forward simulations with a host of parameters to model the expansion of EDAR, so that it fit the distribution pattern that is realized (see the supplements here for the parmeters). To make a long story short they infer that there was one mutation on the order of ~30,000 years before the present, and that it swept up in frequency driven by selection coefficients on the order of ~0.10 (10% increase relative fitness, which is incredibly powerful!). This is on the extreme end of selective sweeps, and likely of the same class as the haplotype blocks which characterize SLC24A5 and LCT (the block is shorter, though that makes sense because of the deeper time depth). Again, I am perplexed why such an ancient allele, which is found in Amerindians, or Munda populations, is absent in Europeans who have putative East Eurasian admixture. The whole does not cohere for me. There is a weak point in one or more of my assumptions.

Then there’s the section on the mouse model. To me this aspect was ingenious, though I’m not particularly able to assess it on its technicalities. The earlier usage of mouse models to test the effects of mutations on EDAR was in the context of coarse copy number changes which resulted in massive dosage changes of protein. The phenotypic outcomes were rather extreme in that case. Here they used a “knockin” model where they recreated the specific EDAR point mutation. Instead of extreme phenotypes they found that the mice were much more normal in their range of traits, though the hair form shifts were well aligned with what occurred in humans. Additionally there were some changes in the number of eccrine glands, with a larger number in the derived East Asian EDAR carriers (with additive effect). Finally they noticed that there were differences in mammary gland pad area and branching. None of this is that surprising, EDAR is a significant regulatory gene which shapes the peripheries and exterior of an organism.

To double check the human relevance of what they found in the mouse model they performed a genome-wide association in a large cohort of Han Chinese. The correlations of particular traits were in the directions that they expected; those individuals with East Asian EDAR variants had thicker hair, shovel-shaped incisors, and a greater density of eccrine glands. It is perhaps important to note that the frequency of the derived variant is so high in Han populations that they didn’t have enough homozygote ancestral genotypes to perform statistics, so their comparisons involved heterozygotes with the derived mutant and also a copy of the ancestral state. This is like SLC24A5 in Europeans, where it is difficult to find individuals of European heritage who have double copies of the non-European modal variant.

Let’s review all the awesome things they did in this study. They dug deeply into the evolutionary genomics of the region around the EDAR, concluding that this haplotype was driven up in frequency from on ancestral variant ~30,000 years ago in a hard selective sweep. And a sweep of notable strength in terms of selection coefficient. This may be one of the largest effect targets of natural selection in the genome of non-Africans over the past 50,000 years. Second, they used a humanized mouse model to explore the range of phenotypes correlated with this mutational change in East Asians. So you have a strong selection coefficient on a locus, and, a range of traits associated with changes on that locus. Third, they confirmed the correlation between the traits and the mutation in humans, despite there being prior research in this area (i.e., they reproduced). This is all great science, and shows the power of collaboration between the groups.

Much of the elegance and power of the paper applies to the discussion section as well, but to be frank this is where things start falling apart for me. You can get a sense of it in The New York Times piece, East Asian Physical Traits Linked to 35,000-Year-Old Mutation. The headline here points to a legitimately important inference from this line of research, many salient physical characteristics of the human races seem to be due to strong selection events at a few loci. In addition to EDAR I’m thinking of the pigmentation loci, such as SLC24A5. I wouldn’t be surprised if there was something similar for the epicanthic fold. If it is visible, and defines between populations differences, it is generally not genomically trivial. There’s usually a story underneath that difference.

In the broad scale of human natural history the problem that arises for me is that we have traits, we have genes under selection, but we have very weak stories to explain the mechanism and context of natural selection. Here there is a strong contrast with the loci around lactase persistence and malaria resistance. In those situations the causal mechanism for the selection seems relatively clear. Critics of evolutionary psychology are wont to accuse the field of ‘Just So’ storytelling, but the same problem crops up in the more intellectually insulated domain of evolutionary genomics (in part because the field is very new, and also mathematically and computationally abstruse). To illustrate what I’m talking about I’m going to quote from the discussion of the above paper:

A high density of eccrine glands is a key hominin adaptation that enables efficient evapo-traspiration during vigorous activities such as long-distance walking and running (Carrier et al., 1984; Bramble and Lieberman, 2004). An increased density of eccrine glands in 370A carriers might have been advantageous for East Asian hunter-gatherers during warm and humid seasons, which hinder evapo-transpiration.

Geological records indicate that China was relatively warm and humid between 40,000 and 32,000 years ago, but between32,000 and 15,000 years ago the climate became cooler and drier before warming again at the onset of the Holocene (Wang et al., 2001; Yuan et al., 2004). Throughout this time period, however, China may have remained relatively humid due to varying contribution from summer and winter monsoons.

High humidity, especially in the summers, may have provided a seasonally selective advantage for individuals better able to functionally activate more eccrine glands and thus sweat more effectively (Kuno, 1956). To explore this hypothesis, greater precision on when and where the allele was under selection—perhaps using ancient DNA sources—in conjunction with more detailed archaeological and climatic data are needed.

A climate adaptation is always a good bet. The problem I have with this hypothesis is that modern day gradients in the distribution of this allele are exactly the reverse of what one might expect in terms of adaptation to heat and humidity. Additionally, is there no cost to this adaptation? After the initial sweep upward, the populations where the derived EDAR mutant is found in high frequencies went through the incredible cold of the Last Glacial Maximum, and groups like the Yakuts are known to have cold adaptations today. Not only that, but the Amerindians from the arctic to the tropics all exhibit a cold adapted body morphology, the historical consequence of the long sojourn in Berengia.

Granted, the authors are not so simplistic, and the somewhat disjointed discussion alludes to the fact that EDAR has numerous phenotypic effects, and it may be subject to diverse positive selection pressures. This seems plausible on the surface, but this complexity of mechanism seems ill-fitted to the fact that the signal of selection around this locus is so clean and crisp. It seems that this is not going to be an easy story to unpack, and there’s a good deal of implicit acknowledgement of that fact in this paper. But tacked right at the end of the main text is this whopper:

It is worth noting that largely invisible structural changes resulting from the 370A allele that might confer functional advantage, such as increased eccrine gland number, are directly linked to visually obvious traits such as hair phenotypes and breast size. This creates conditions in which biases in mate preference could rapidly evolve and reinforce more direct competitive advantages. Consequently, the cumulative selective force acting over time on diverse traits caused by a single pleiotropic mutation could have driven the rise and spread of 370A.

A simple takeaway is that the initial climatic adaptation may have given way to a cultural/sexual selective adaptation, whereby there was a preference for “good hair” as exemplified by pre-Western East Asian canons (black and lustrous), as well as a bias toward small breasts. This aspect gets picked up in The New York Times piece of course. I’ll quote again:

But Joshua Akey, a geneticist at the University of Washington in Seattle, said he thought the more likely cause of the gene’s spread among East Asians was sexual selection. Thick hair and small breasts are visible sexual signals which, if preferred by men, could quickly become more common as the carriers had more children. The genes underlying conspicuous traits, like blue eyes and blond hair in Europeans, have very strong signals of selection, Dr. Akey said, and the sexually visible effects of EDAR are likely to have been stronger drivers of natural selection than sweat glands.

The passage here is ambiguous because the author of the article, Nick Wade, doesn’t use quotes, and I don’t know what is Akey and what is Wade’s gloss on Akey. For example, for theoretical reasons of reproductive skew (a few men can have many children) in general sexual selection is considered to be driven most often by female preference for male phenotypes. I assume Akey knows this, so I suspect that that section is Wade’s gloss (albeit, a reasonable one given the proposition of preference for smaller breasts). The main question on my mind is how seriously prominent population geneticists such as Joshua Akey actually take sexual selection to be as a force driving variation and selection in human populations. It seems that quite often sexual selection is presented as a deus ex machina. A phenomenon which can rescue our confusion as to the origins of a particular suite of traits. But our assessment of the likelihood of sexual selection presumably has to be premised on prior expectations informed by a balance of different forces one can gauge from the literature, and here my knowledge of the current sexual selection literature is weak. Perhaps my skepticism is premised on my ignorance, and the population geneticists who proffer up this explanation are more informed as to the state of the literature.

All this brings me back to the farcical title. When this paper first made news last week I was having dinner with a friend of Japanese heritage (who spent his elementary school years in Japan). I asked him point blank, “Do you like small breasts?” His initial response was “WTF!?! Razib,” but as a mouse geneticist he understood the thrust of my question after I outlined the above results to him. From personal communication with many East Asian American males I am not convinced that there is a overwhelmingly strong preference for small breasts within this subset of the population. But the key here is American. These are individuals immersed in American culture. The norms no doubt differ in East Asia. The typical visual representation of celebrity East Asian females that we see in the American media depict individuals who are slimmer and more understated in their secondary sexual characteristics than is the norm among Western female celebrities (e.g., Gong Li, the new crop of Korean pop stars, even taking into account the plastc surgery of the latter). Part of this is no doubt the reality that the normal range of variation across the population differs, and part of it may be the nature of aesthetic preferences.

But the possibility of deep rooted psychological reasons driving sexual selection (to my knowledge there was no culture which spanned South China and Siberia) brings us back to old ideas about the Pleistocene mind. And, it brings us back to evolutionary psychology, a field which is the whipping boy of both skeptics of the utility of evolutionary science in understanding human nature, and rigorous practitioners of evolutionary biology. And yet here it is not the evolutionary psychologists, but rock-ribbed statistical geneticists who I often see being quoted in the media invoking sexual selection. But do we know it is sexual selection, or is it just our best guess? Because more often than not best guesses are wrong (though best guesses are much more likely to be right than worst guesses!).

Evolutionary genomics has come a long way in the past 10 years. We know, for example, the genetic architecture and some aspects of the natural history of many traits. But, there are still shortcomings. Lactase persistence is the exception to the rule. Even a phenotype as straightforward as human pigmentation has no undisputed answer as to why it has been the repeated target of selection across Eurasia over the past 40,000 years. Oftentimes the right answer is simply that we just don’t know.

Citation: http://dx.doi.org/10.1016/j.cell.2013.01.016

(Republished from Discover/GNXP by permission of author or representative)
 
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A comment below:

Does the higher genetic diversity in sub-Saharan Africans explain why mixed children of blacks + other couples usually look more black than anything?

As in, the higher number of genetic characteristics overwhelms those of the other parent and allows them to be present in the child.

But this makes you ask: is the assumption that people with some African heritage tend to exhibit that heritage disproportionately even true? From an American perspective the answer is obviously yes. But from a non-American perspective not always. Why? Doe the laws of genetics operate differently for Americans and non-Americans? I doubt t. Rather, hypodescent, and its undergirding principle of the “reversion to the primitive type” are still background assumptions of American culture. In fact today black Americans are perhaps most aggressive and explicit in outlining the logic and implications of the “one drop rule,” though non-blacks tend to accept it as an operative principle as well.

Assessing someone’s racial identity has a subjective aspect. We see through the mirror darkly, and that’s a function of the cultural preconditions of gestalt cognition. But there are some objective metrics we can look at it. Foremost among them is skin color.

The locus SLC24A5 is probably the largest effect gene which impacts normal human variation in skin color. It is responsible for 25-40% of the difference in pigmentation between Europeans and Africans. If you have the genotype AA you are lighter than if you are AG, and if you are AG you are lighter than GG. Almost all Africans are GG, and almost all Europeans are AA. What’s the impact on African Americans then? Below are two panels which show the distribution of skin pigmentation using a quantitative metric as a function of the genotypes.

If you don’t get the significance, let me highlight the text for this figure:

Effect of SLC24A5 genotype on pigmentation in admixed populations. (A) Variation of measured pigmentation with estimated ancestry and SLC24A5 genotype. Each point represents a single individual; SLC24A5 genotypes are indicated by color. Lines show regressions, constrained to have equal slopes, for each of the three genotypes. (B) Histograms showing the distribution of pigmentation after adjustment for ancestry for each genotype. Values shown are the difference between the measured melanin index and the calculated GG regression line (y = 0.2113x + 30.91). The corresponding uncorrected histograms are shown in fig. S7. Mean and SD (in parentheses) are given as follows: for GG, 0 (8.5), n = 202 individuals; for AG, –7.0 (7.4), n = 85; for AA, –9.6 (6.4), n = 21.

The difference between GG and AG is 7. AG to AA is 2.6. In short you see that the allele which results in lighter skin exhibits dominance to the allele which is correlated with darker skin! Strangely, this is not an isolated fluke.

The results to the left are again the quantitative pigmentation values for an admixed population of mostly African descent, with some European ancestry. In this case it is for the KITLG locus, which can explain 20-25% of the difference in value between European and African populations in terms of pigmentation. The G allele here is the lightening variant. You see that GG are lighter than AG, who are lighter than AA. But what are the median values? -4.7 for GG, -2.9 for AG, and 1.9 for GG. The difference between AG and AA is 4.2. Between AG and GG is 1.8. Again you note that the lightning variant exhibits dominance on this phenotype in relation to the darker variant!

The reason I’m rehashing these results (which I’ve presented before) is that in this case the cultural norm, at least in the U.S.A., is at variance at what is the reality on the phenotypic level. I was surpised when I first saw these results, and everyone else I’ve mentioned them to is moderately surprised. Why? Naively I assume that’s because in the U.S.A. a white phenotype is “default,” and deviations from that default prototype are particularly salient. Less noticeable to us is the possibility that those deviations may still result in a physical type closer to the default prototype than other types. More colloquially someone like Colin Powell is black because of the color of his skin, not white . But objectively his skin color is closer to white than it is to black (and judging from his features his ancestry is probably more European than it is African).

Of course I’m not arguing here that all non-African features are dominant to African features. In terms of hair form it seems that this is not true. But again, this is partly an artifact of how we as humans classify the phenotype. People of mixed ancestry often have a different hair form from both their parents. It simply is the fact though that we “bin” moderately kinky and very kinky hair together into one class.

The moral of the story is that when we talk about human population differences we need to be very careful of separating the subjective from the objective. Obviously this has been a fraught domain, and the best way to move it back into respectable mainstream discourse is to bleed it of its less scientific aspects.

 

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Admixture, Genetics, Race 
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A fascinating comment below:

In traveling across America, the Scots Irish have consistently blown my mind as far and away the most persistent and unchanging regional subculture in the country. Their family structures, religion and politics, and social lives all remain unchanged compared to the wholesale abandonment of tradition that’s occurred nearly everywhere else.

Unfortunately, this has a lot to do with a powerful and long-running strand of paranoia and xenophobia. I’ve ridden trains through the rail towns of WV and KY and been regarded with more unprovoked hatred than anywhere else on Earth. On the other hand, when I’ve been introduced to their clan-based social structures by close friends, it is a uniquely close-knit and life-affirming culture that I’ve been honored to participate in.

What stuck me about this comment is that it is the sort of statement you regularly see from Western anthropologists or adventure tourists in relation to indigenous colored peoples the world over. That is, a parochial clannish folk trying to hold onto to their traditions, albeit with the downside of being inward looking and often regressive (downside from the perspective of Westerners that is). What these people lack in cosmopolitan openness, they make up for in adherence to authentic values which can’t but help earn some admiration. Substitute “Scots-Irish” for “Pashtun”, “Hmong” or “Berber” and you will see what I mean.


If you are not aware (e.g., you are not American) the Scots-Irish in this context refers to a melange of peoples who emigrated to the New World from Ireland and the border region between Scotland and England in the middle of the 1700s. These were not Catholic Irish, or Gaelic speaking Highlanders. Rather, they were tough Presbyterian Protestants, whose cousins still remain committed to their distinctive identity in Ulster in Northern Ireland. They arrived to the port of Philadelphia, and spread south via the spine of the Appalachians. Many of the traits that non-Americans perceive as “Yankee” are ironically those of Scots-Irish, who were most certainly not Yankees (i.e., Puritan New Englanders). The Scots-Irish were the prototypical cowboys, pushing into the Appalachian wilderness despite the attempts of the British crown to restrain them.

Though the Scots-Irish are not “Pilgrim stock” in their length residence on the American continent, the majority were not immigrants to the United States, they were settlers of the American colonies. Their’s was part of the founding culture of the United States, and it still leaves its stamp on our society in its politics and mores, for good or ill (that depends on your perspective!). But one aspect of Scots-Irish identity is that to a great extent it has decoupled itself from any “Old Country” consciousness. A broad swath of the Eastern American Uplands is dominated by people who give their ethnicity as American. After 250 years they have only the vaguest recollections of the nature of their British antecedents.

In Ornamentalism David Cannadine makes the case that the British saw their Empire through the lens of class as much, or more than, race. Though one can quibble with the magnitude of Cannadine’s argument, I think one must grant that it is part of the picture, if not the whole picture. The importance of class in England, and more or less in Europe as a whole, is contrasted with its relatively lower salience in the United States. Why? One can make a classic materialist argument that in a labor scarcity-land surplus regime which characterized the early American republic the ossified class systems of the Old World simply could not develop. But another aspect which must be acknowledged is that the early American republic also saw the emergence of a white man’s republic, where implicit white identity gave way to the expansion of suffrage to non-property holding white males as a natural right, and the revocation of what suffrage existed for non-whites based on their racial character. The Scots-Irish were a major part of this cultural evolution, being as they were generally part of the broad non-slave holding class in the South and Border States. Though they may not have had the wealth of lowland planters, the Scots-Irish were part of the aristocracy of skin.

But ultimately this system, which waxed around 1900, has left us in the 21st century in a confused state when it comes to talking about race and class. The academic ‘discourse’ about white privilege acknowledges rhetorically the reality of class differences amongst whites, but in practice this issue never realizes itself in any actionable manner. In the 19th century this was something that non-elite whites might have viewed positively, as the bracketing of all whites together as one political nation which excluded all non-whites, irrespective of the latter’s ‘respectability’ in specific cases, redounded to their benefit. The poorest white was superior to the wealthiest non-white in the social culture of the United States in the 19th century. Race trumped class in totality. But today the elision of distinctions among white Americans without explicit ethnicity (e.g., Polish, Jewish, etc.), those whites whose Anglo-American heritage is part of the cultural DNA of this nation, results in the bracketing of all together as beneficiaries of white privilege.

This position of Scots-Irish as part of the aristocracy of race and white skin privilege leads to perverse situations. It is true that Scots-Irish Americans are arguably among the more racist white ethnic groups. But this reality can easily be mitigated by a Marxist explanation of their relative lack of economic privilege. How many people would guess that the poorest county in America is 99% non-Hispanic white? But this amelioration of contempt for the retrograde attitudes of poor whites on the part of elites is blocked in part by the racialized consensus of the 19th century which served to uplift the Scots-Irish! As I have noted before, the 21st narrative of white privilege is in many ways simply a normative inversion of the 19th century narrative of white supremacy.

All this leads to the strangeness of American in 2012 which might perplex outsiders. For example, Malia Obama, the daughter of two individuals with law degrees from Harvard, would be able to benefit from affirmative action,* because she lacks white skin privilege. In contrast, the child of a poor family from Appalachia who was white would not gain any preference, because by their nature as a white person they had the right of white skin privileged from which they benefited. You might assert here that there are points in favor for geographic and class diversity at elites schools. But from what I have read Thomas Espenshade’s work shows that elite universities tend to discriminate against rural and lower class whites (as well as Asians) to maintain diversity through admissions of sufficient numbers blacks and Hispanics. Note: well connected whites with high socioeconomic statuses are doing fine under the current dispensation. Unfortunately, non-elite whites have contributed to their own situation via the construction of the racial republic in the 19th century, which has now been turned upside down to their disadvantage.

* To be fair, the most affirmative action would be based on her status as the daughter of a president of the United States, not her race.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Culture, Race 
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Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at http://www.razib.com"