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.
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.
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.
It is sometimes fashionable to assert that higher socioeconomic status whites are the sort who will impose integration on lower socioeconomic status whites, all the while sequestering themselves away. I assumed this was a rough reflection of reality. But after looking at the General Social Survey I am not sure that this chestnut of cynical wisdom has a basis in fact. Below are the proportions of non-Hispanic whites who have had a black friend or acquaintance over for dinner recently by educational attainment:
35% – Less than high school
36% – High school
47% – Junior College
45% – Bachelor
59% – Graduate
I thought this might have been a fluke, so I played around with the GSS’s multiple regression feature, using a logistic model. To my surprise socioeconomic status was positively associated with having a black person over for dinner, and age negatively associated. These two variables in fact tended to exhibit equal magnitude values in opposition, and always remained statistically significant. Just to clear, I created a variable Non-South vs. South below (being Southern increases likelihood of having had a black person over for dinner). All the individuals surveyed are non-Hispanic whites for the year 2000 and later. You can add and remove variables, but SEI and age tend to be rather stable, and statistically significant, throughout.
There have been a variety of responses to my column in The Crux on race. To be fair, because the audience for The Crux does not consist of genome nerds I engaged in some first approximations which some readers have taken objection to. For example, the genetic architecture of blue vs. brown eye inheritance is ‘quasi-Mendelian,’ with ~75 percent of the variation in Europeans on this trait attributable to variation in the region of the HERC2 and OCA2 genes. But I thought, and still think, that a rough re-characterization of the trait as a recessive one with a monogenic Mendelian inheritance pattern can be justified for didactic purposes (just like one can justify the idea that whole human genomes have been sequenced, even if there are large gaps, and known errors in regions of repeats).
But the comments over at Richard Dawkins’ website have been rather amusing as a whole. Some people were patronizingly pedantic, and I don’t have time respond in detail (the real response would be: read my blog!). But some comments are easy to answer:
I’d like to hear Dawkins’ response to this, I’ve read all of his books and he’d surely disagree with the author of that article.
Easy. He discusses race in The Ancestors’ Tale (a book the commenter claims to have read):
In the comments below:
You should include a Moroccan or otherwise native North African sample. Without a North African sample West Africans act as proxy for some of that North African ancestry that does exist in Iberia, specially the Western third (Portugal, Galicia, Extremadura, León, etc.) Doing that your analysis would become more precise and you could make better informed claims.
I was reading through all the entry and there was no mention to the rather surprising notable West African component in Iberians other than Basques. For my somewhat trained eye it is clear that this is a proxy for North African ancestry and not directly West African ancestry. This is demonstratedly also the case in Canary Islands, at least to a large extent, and, by extension in Cuba (which is nearly identical to your average Canarian), at least Cuba-1. Cuba-2 seems actually admixed at low levels and both seem to have some Amerindian ancestry not existent in Spain.
This is a fair point. I switched computers recently, and the Behar et al. data set I had seems to have become corrupted. So I snatched the Mozabites from the HGDP, and removed the Gujaratis from the previous run. I also added Russians, Druze, and some extra Amerindian groups. At K = 7 this pattern jumped out:
About a week ago I put up a post put on an analysis of a paper which reported on the ancestral make up of 50 Cubans (as well as assorted other Hispanic/Latino groups). One aspect of the paper which was somewhat notable is that 1 out of 3 Cubans were 90 percent or more European in ancestry. The notability of this is that is that 5 out of 6 Cuban Americans identify as white. That is, of European ancestry. The main caveat here is that these Cubans were sampled from New York City, and to a lesser extent the Midwest. The fact of non-European admixture in putatively white European individuals from Latin America is not surprising. Our prior expectation should be that the admixture is non-trivial, though not preponderant. For example, the majority of the white population of Argentina has Amerindian ancestry (or, more precisely ~15 percent of the aggregate ancestry of Argentineans is Amerindian). At least notionally Cuba is a much more racially mixed culture than Argentina, so non-white admixture in even white Cubans is not surprising.
Based on the above paper (and the data which you can find on other Latin American whites), as well as the genotyping of two Cuban American acquaintances, I asserted that on the order of ~10 percent of the ancestry of the average white Cuban was going to be African. Naturally this prompted some objections. Some of the individuals were not too polite. I think the primary issue that I have to be honest about this is this: I don’t really care too much about the topic on a visceral level. Now, I’m interested in it. And the specific cases illuminate a greater whole, which comments upon various demographic and population genetic dynamics. But I don’t have a strong investment in the specific instance of the particular ancestral quanta of Cubans, or any other group really.
Second, there was some objection to punctilious attention to scientific methodology, such as representativeness and sample size. This is a serious objection in the abstract, but the reality is that a generation of genomics has been performed with lineages as unrepresentative as “Utah whites.” Science and knowledge seeking is frankly operationally an ad hoc and sloppy process, without great attention to the book of proper scientific methodology. When we don’t have much information, any extra information is often useful, so long as we keep in mind the error that this introduces into the process.
All that being said, one commenter brought to my attention an interesting paper. It reports 6 percent African ancestry in a very large population of white Havana Cubans. The main downside is that they used only 60 SNPs, as opposed to the 60,000 SNPs in the above study. Of course those 60 SNPs would be “ancestrally informative,” but at 6 percent vs. 10 percent (my prior estimate), I’m not sure that I should totally trust the precision and update my values. But I think that nevertheless this study converges upon the same qualitative result: white Cubans, like white Latin Americans in generally, seem to usually exhibit non-trivial amounts of non-European ancestry.
But in the interests of moving the discussion forward, the commenter who brought the above paper to my attention supplied two 23andMe genotypes of Cuban Americans: herself and her husband. I will now refer to her as “Cuba 1″ and her husband as “Cuba 2.” I created a pooled data set of the following populations:
In a follow up to a post below, a new paper in PLoS Genetics has some data on American Hispanics. Specifically, Puerto Ricans, Dominicans, Mexicans, and Cubans, as well as assorted Central and South Americans. I am not too interested in the cases except Cubans; no one doubts the mixed heritage of the other groups, though the African ancestry of Mexicans, and some Central and South Americans may surprise (again, I have to note that this not surprising in light of history, and has been robustly confirmed in the genomic literature).
But Cuban Americans are somewhat a special case. The vast majority, specifically, 85 percent, identify as white. This is a higher proportion than the number of self-identified whites in Cuba, and a function of the skewed nature of the migration out of Cuba socially and economically. By and large the white elite of the island fled Castro’s revolution to a far greater extent than the black lower classes. And contrary to American stereotypes of Latin American ease and openness about race, Cuba was a relatively stratified society, albeit not characterized by hypodescent. Slavery was not abolished on the island until 1884. Additionally, Cuba did experience a relatively large wave of Spanish immigration in the early 20th century. I have taken the claims of “pure Spanish ancestry” on face value in the past because of this history. But further genomic evidence makes me reconsider the biases in the reporting of ancestry. For example, I have heard singer Gloria Estefan mention that her heritage was of recent Spanish immigrants from Cuba, but Wikipedia indicates that this is the origin of her maternal lineage. It leaves her paternal lineage unaccounted for. I have no doubt that her father’s family were white Cubans, but if their roots on the island were somewhat deep, I am also sure that they had non-trivial African, and possibly Amerindian, ancestry.
The reason for some of these assertions from are the genomic results, like figure below from the paper mentioned above (reedited for some clarity and specificity).
In the recent ‘do human races’ exist controversy Nick Matzke’s post Continuous geographic structure is real, “discrete races” aren’t has become something of a touchstone (perhaps a post like Cosma Shalizi’s on I.Q. and heritability).* In the post Matzke emphasized the idea of clines, roughly a continuous gradient of genetic change over space. Fair enough. But in the map above I traced two linear transects. I would suggest that anyone who has a general understanding of the demographics of South-Central Eurasia would immediately anticipate that these transects would reveal a relatively sharp break in allele frequencies. True, there are intermediate populations between the two end points, in Nepal, and on the fringes of India’s northeastern states. But clearly about halfway through the southwest-northeast transect you’ll see a rapid shift in allele frequencies. The blue transect is different, insofar as the change occurs very near its eastern pole. In Bengal, 85% of the length of the transect from its western terminus, the populations will still be far closer genetically to those on the western pole than those just to the east!
I’m too busy to really blog today, but I thought of putting up a post, the gist of which was actually expressed in Ian’s comment below:
When I was younger, I thought of human races as archetypes, and the variation between them a product of mixing. I blame it on the fact that I read Coon when I was about 14. Still, as a (half)Indian, it’s hard to see reconcile the reality of a billion people in the subcontinent with models that try to classify people into 3-5 races. As I learned more biology, I came to the conclusion that human variation was clinal, and race was really an artefact of where you chose to sample along the continuum…as a plant ecologist, I think about things like that a lot. (I’m also somewhat skeptical of ecozones.)
Thanks to a number of convergent strands (of which Razib’s blogging has been a key element), I have come to a rather different conclusion. Race, in my opinion, is more a feature of agriculture than evolution.
Consider two possible models of race: Model 1, in which sharp distinctions existed before the Neolithic, and have been maintained and enhanced as certain groups adopted agriculture and displaced their hunter-gatherer neighbours; and Model 2, in which variation was clinal prior to the Neolithic, but that the immense demographic expansion of certain groups expanded THEIR specific points on the continuum, and brought them into contact (or nearly into contact) with other expansionist agriculturalists.
To me, the Model 2 seems more plausible than Model 1. Is that an argument against race? No, but it does suggest that races shouldn’t really be seen as “locally adapted optima” and rather, should be seen more as transient phenomena produced by historic contingency. Whether this means that race is “real” or not is, to me, a little beside the point. But I’m not convinced by Coyne’s argument that these differences represent the “accumulation of genetic differences between isolated populations”.
After my post on the ‘race question’ I thought it would be useful to point to Jerry Coyne’s ‘Are there human races’?. The utility is that Coyne’s book Speciation strongly shaped my own perceptions. I knew the empirical reality of clustering before I read that book, but the analogy with “species concept” debates was only striking after becoming more familiar with that literature. Coyne’s post was triggered by a review of Race?: Debunking a Scientific Myth and Race and the Genetic Revolution: Science, Myth, and Culture. He terms the review tendentious, and I generally agree.
In the early 20th century Western intellectuals of all political stripes understood what biology told us about human taxonomy. In short, human races were different, and the white European race was superior on the metrics which mattered (this was even true of Left-Socialist intellectuals such as H. G. Wells and Jack London). In the early 21st century Western intellectuals of all political stripes understand what biology teaches us about human taxonomy. Human races are basically the same, and for all practical purposes identical, and equal on measures which matter (again, to Western intellectuals). As Coyne alludes to in his post these are both ideologically driven positions. One of the main reasons that I shy away from modern liberalism is a strong commitment to interchangeability and identity across all individuals and populations as a matter of fact, rather than equality as a matter of legal commitment. In a minimal government scenario the details of human variation are not of particular relevance, but if you accept the feasibility of social engineering (a term I am not using in an insulting sense, but in a descriptive one) you have to start out with a model of human nature. So this is not just an abstract issue. For whatever reason many moderns, both liberals and economic conservatives, start out with one of near identity (e.g., H. economicus in economics).
I want to highlight a few sections of Coyne’s post:
Recently Jason Antrosio began a dialogue with readers of this weblog on the “race question.” More specifically, he asked that we peruse a 2009 review of the race question in the American Journal of Physical Anthropology. Additionally, he also pointed me to another 2009 paper in Genome Research, Non-Darwinian estimation: My ancestors, my genes’ ancestors. Normally I don’t react well to interactions anthropologists who are not Henry Harpending or John Hawks. But Dr. Antrosio engaged civilly, so I shall return the favor.
I did read all the papers in the American Journal of Physical Anthropology special issue, as well the Genome Research paper. My real interest here are specific questions of science, not history or social science. But I will address the latter areas rather quickly. I am not someone who comes to this totally naked of the history or social science of the race question. I’ve read many books on the topic. And as a colored person who has moderate experience with racism I get rather bored and irritated with excessively patronizing explanations of how racism afflicts us coloreds from white academics (non-white academics who focus on this subject are usually careerists or activists who don’t have to make much pretense toward scholarly substance and can be duly ignored, at least in my experience). The main point which I think we can all agree upon is that colloquial understanding of race has only a partial correlation with any genetic understanding of race. I myself have ranted against the confusions which have ensued because of the conflation of the two classes, and it is certainly a legitimate area of study, but it is not my primary concern. And importantly, I have no great primary interest in battling racism.
Many of our categories are human constructions which map upon patterns in nature which we perceive rather darkly. The joints about which nature turns are as they are, our own names and representations are a different thing altogether. This does not mean that our categories have no utility, but we should be careful of confusing empirical distributions, our own models of those distributions, and reality as it is stripped of human interpretative artifice.
I have argued extensively on this weblog that:
1) Generating a phylogeny of human populations and individuals within those populations is trivial. You don’t need many markers, depending on the grain of your phylogeny (e.g., to differentiate West Africans vs. Northern Europeans you actually can use one marker!).
2) These phylogenies reflect evolutionary history, and the trait differences are not just superficial (i.e., “skin deep”).
The former proposition I believe is well established. A group such as “black American” has a clear distribution of ancestries in a population genetic sense. The latter proposition is more controversial and subject to contention. My own assumption is that we will know the truth of the matter within the generation.
I was holding my 1-year-old, ambling about downtown with some friends. White friends. She must have thought my boy belonged to one of them.
There’s a simple explanation: I’m black but my son, Ashe, is white. At least he looks it.
But things are more complicated than that.
I’m actually half black and half white. It should come as no surprise, though, that even as sophisticated as we’ve become about people of mixed parentage, I’m pigeonholed as black. If someone asks and I don’t have time to go deeper, that’s what I call myself.
Ashe is mixed too. His mother, my wife, Vanashree, is half white and half South Asian, with roots in India. She has olive skin, and Ashe is slightly lighter than she is.
This surprised us. When Ashe was born, one of the first things I said to Vanashree was, “Honey, he’s so light!” We chuckled, poking fun at our assumptions.*
One of the reasons I post regularly on the genetics of mixed-race people and their physical appearance is that I don’t think the media does a good job. There’s a “freak show” element which titillates but does not illuminate. This in a period in the United States where the absolute number of people of mixed origin is increasing rapidly due to intermarriage. In fact for years I’ve gotten inquiries from the parents of mixed-race children about the scientific details of the genetics, because they are regularly questioned in depth as to how the children came to look how they look (the emails are always from women, more on that later). A relatively well written article in The New York Times illustrates some of the issues, insofar as the focus is totally on social context and dynamics, with not even a small nod to the science. The story is about a mixed-race woman (mother white and father black) who is married to a white man, whose children don’t “look black.” Specifically, her two daughters are very light-skinned, and the younger one is boldly blonde.
Here’s the jump off point of the piece:
“How come she’s so white and you’re so dark?”
The question tore through Heather Greenwood as she was about to check out at a store here one afternoon this summer. Her brown hands were pushing the shopping cart that held her babbling toddler, Noelle, all platinum curls, fair skin and ice-blue eyes.
The woman behind Mrs. Greenwood, who was white, asked once she realized, by the way they were talking, that they were mother and child. “It’s just not possible,” she charged indignantly. “You’re so…dark!”
It was not the first time someone had demanded an explanation from Mrs. Greenwood about her biological daughter, but it was among the more aggressive….
Of course it’s possible. The science behind this is trivially plain. The biological mother has alleles which code phenotypes distinctive of Europeans and Africans. Because her father is African American she is even likely to have more European ancestry than African ancestry (median African American is ~80% African and ~20% European). Genes which control variation in skin pigmentation at the scale of racial differences are distributed across half a dozen loci, but with blue vs. brown eye color there’s really only one locus which explains most (though not all) of the variation. That probably explains how both the daughters have blue eyes. The mother is probably a heteozygote, and the father is a homozygote. That means that any one of their children has a ~50% chance of having blue eyes and a ~50% chance of having brown eyes. So the chance of both daughters turning out to have blue eyes is ~25%. But obviously the science isn’t the meat of the piece. I just wish they’d given a quick explicit nod to it so that people would know why the outcome is as it is. It’s not rocket science.
I was pointed today to a piece in the BBC titled What makes a mixed race twin white or black?. The British media seems to revisit this topic repeatedly. There are perhaps three reasons I can offer for this. First, it tends toward sensationalism. Even though the BBC is relatively staid, when it comes to science it converges upon the tabloids. Second, because the number of non-whites in Britain is relatively small, there is a higher proportion of intermarriages between minorities and the white majority (from the perspective of minorities). This is especially true of people of Afro-Caribbean ancestry. So of the proportion of minorities a larger fraction are recently mixed in Britain than in the USA. Finally, the United States has a more complex attitude toward race relations than the United Kingdom, because the former has traditionally had a large non-white minority while the latter has only had so since the years after World War II. I suspect that “black-white twins” stories would seem in bad taste on this side of the pond, and bring up certain memories best forgotten.
Now, there are fallacies, confusions, and misleading shadings, in the BBC piece. I’ll hit those first before reviewing what’s going on here when fraternal twins exhibit totally different complexions.
One thing that came to the fore in late 2008 was the worry that a financial regulatory regime which had been exceeding lax was now more conscious of the excesses of the previous era. The problem being that one will not necessarily be prepared for the next crisis. Similarly, terrorist actions such as those of the 9/11 hijackers are probably unlikely in their specific details, because the element of surprise is gone. That’s what makes much of the TSA “security” measures so frustrating for many people, there is a strong suspicion that the authorities are aiming to prevent the previous operation, when real terrorists will naturally alter tactics.
I thought of that when forwarded a link to a new book by a friend, Race and the Genetic Revolution: Science, Myth, and Culture. Here’s the summary:
Do advances in genomic biology create a scientific rationale for long-discredited racial categories? Leading scholars in law, medicine, biology, sociology, history, anthropology, and psychology examine the impact of modern genetics on the concept of race. Contributors trace the interplay between genetics and race in forensic DNA databanks, the biology of intelligence, DNA ancestry markers, and racialized medicine. Each essay explores commonly held and unexamined assumptions and misperceptions about race in science and popular culture.
This collection begins with the historical origins and current uses of the concept of “race” in science. It follows with an analysis of the role of race in DNA databanks and racial disparities in the criminal justice system. Essays then consider the rise of recreational genetics in the form of for-profit testing of genetic ancestry and the introduction of racialized medicine, specifically through an FDA-approved heart drug called BiDil, marketed to African American men. Concluding sections discuss the contradictions between our scientific and cultural understandings of race and the continuing significance of race in educational and criminal justice policy.
In the comments below Antonio pointed me to this working paper, What Do DNA Ancestry Tests Reveal About Americans’ Identity? Examining Public Opinion on Race and Genomics. I am perhaps being a bit dull but I can’t figure where its latest version is found online (I stumbled upon what looks like another working paper version on one of the authors’ websites). Here’s the abstract:
Genomics research will soon have a deep impact on many aspects of our lives, but its political implications and associations remain undeveloped. Our broad goal in this research project is to analyze what Americans are learning about genomic science, and how they are responding to this new and potentially fraught technology.
We pursue that goal here by focusing on one arena of the genomics revolution — its relationship to racial and ethnic identity. Genomic ancestry testing may either blur racial boundaries by showing them to be indistinct or mixed, or reify racial boundaries by revealing ancestral homogeneity or pointing toward a particular geographic area or group as likely forebears. Some tests, or some contexts, may permit both outcomes. In parallel fashion, genomic information about race can emphasize its malleability and social constructedness or its possible biological bases. We posit that what information individuals choose to obtain, and how they respond to genomic information about racial ancestry will depend in part on their own racial or ethnic identity.
We evaluate these hypotheses in three ways. The first is a public opinion survey including vignettes about hypothetical individuals who received contrasting DNA test results. Second is an automated content analysis of about 5,500 newspaper articles that focused on race-related genomics research. Finally, we perform a finer-grained, hand-coded, content analysis of about 700 articles profiling people who took DNA ancestry tests.
Three major findings parallel the three empirical analyses. First, most respondents find the results of DNA ancestry tests persuasive, but blacks and whites have very different emotional responses and effects on their racial identity. Asians and Hispanics range between those two poles, while multiracials show a distinct pattern of reaction. Second, newspaper articles do more to teach the American reading public that race has a genetic component than that race is a purely social construction. Third, African Americans are disproportionately likely to react with displeasure to tests that imply a blurring of racial classifications. The paper concludes with a discussion, outline of next steps, and observations about the significance of genomics for political science and politics.
I would say The Mismeasurement of Man is one of the most commonly cited books on this weblog over the years (in the comments). It comes close to being “proof-text” in many arguments online, because of the authority and eminence of the author in the public mind, Stephen Jay Gould. I am in general not particularly a fan of Gould’s work or thought, with many of my sentiments matching the attitudes of Paul Krugman in this 1996 essay:
….Like most American intellectuals, I first learned about this subject [evolutionary biology] from the writings of Stephen Jay Gould. But I eventually came to realize that working biologists regard Gould much the same way that economists regard Robert Reich: talented writer, too bad he never gets anything right. Serious evolutionary theorists such as John Maynard Smith or William Hamilton, like serious economists, think largely in terms of mathematical models. Indeed, the introduction to Maynard Smith’s classic tract Evolutionary Genetics flatly declares, “If you can’t stand algebra, stay away from evolutionary biology.” There is a core set of crucial ideas in his subject that, because they involve the interaction of several different factors, can only be clearly understood by someone willing to sit still for a bit of math. (Try to give a purely verbal description of the reactions among three mutually catalytic chemicals.)
But many intellectuals who can’t stand algebra are not willing to stay away from the subject. They are thus deeply attracted to a graceful writer like Gould, who frequently misrepresents the field (perhaps because he does not fully understand its essentially mathematical logic), but who wraps his misrepresentations in so many layers of impressive, if irrelevant, historical and literary erudition that they seem profound.
Yes, I am aware that some biologists would disagree with this assessment of Gould’s relevance. But I remain generally skeptical of his arguments, though over the years I have become more accepting of the necessity of openness to a sense of ‘pluralism’ when it comes to the forces which shape evolutionary processes. And certainly there is interesting exposition in a book like The Structure of Evolutionary Theory, but there was no need for ~1500 pages (Brian Switek did fine with a little over ~300 pages in covering similar territory as the first half of the book). Whatever valid positions Gould staked out in opposition to excessive adaptationist thinking on the part of the neo-Darwinian orthodoxy of the mid-20th century, his penchant for self-marketing and repackaging of plausible but not particularly novel concepts was often destructive in my experience to the enterprise of a greater public understanding of science.
When I was in 8th grade my earth science teacher explained to the class proudly that he was not a “Darwinian,” rather, he accepted punctuated equilibrium. One must understand that much of his audience was Creationist in sympathy because of the demographics of the region, but I was frankly appalled by his explicit verbal rejection of “Darwinism,” because I knew how the others would take it (my best friend in the class was a Creationist and he kept chuckling about “monkeys turning into men” throughout the whole period). I remained after to further explore this issue with my teacher. I expressed my bewilderment as best as I could, and it came to pass that my teacher explained that he had arrived to his skepticism of the rejected model of Darwinism via the works of Stephen Jay Gould. With his silver tongue Gould had convinced him that the future of evolutionary science lay with punctuated equilibrium, which had already overthrown the older order. A 13 year old can only go so far, and so I moved on.
The 1970 Census was the first time that a “Hispanic” identifier was used and data collected with the question. The definition of “Hispanic” has been modified in each successive census. The 2000 Census asked if the person was “Spanish/Hispanic/Latino”.
The U.S. Office of Management and Budget currently defines “Hispanic or Latino” as “a person of Mexican, Puerto Rican, Cuban, South or Central American, or other Spanish culture or origin, regardless of race.”
Because Hispanics can be any race, you need to look at their own self-identification. The breakdowns as per the American census are that somewhat over 50% of American Hispanics/Latinos identify as white, most of the rest as “some other race,” with a small minority as black, Native American, etc.
This came to mind when I saw this paper in BMC Genetics, Comparing self-reported ethnicity to genetic background measures in the context of the Multi-Ethnic Study of Atherosclerosis (MESA). The issue is that when you’re doing association studies between genes and diseases you want to control for population structure. For example, if disease X is found in Chinese Americans to a higher degree than the general population, then all the alleles distinctive to Chinese Americans would correlate with disease X in an aggregated pool. Self-reports are pretty good, but on the margin there is now some juice to squeeze out of the data sets by using ancestrally informative markers to “clean up” the outliers within the populations.
Here are the results:
Four clusters are identified using 96 ancestry informative markers. Three of these clusters are well delineated, but 30% of the self-reported Hispanic-Americans are misclassified. We also found that MESA SRE provides type I error rates that are consistent with the nominal levels. More extensive simulations revealed that this finding is likely due to the multi-ethnic nature of the MESA. Finally, we describe situations where SRE may perform as well as a GBMA in controlling the effect of population stratification and admixture in association tests.
Below is a principal component analysis plot which illustrates the largest dimensions of genetic variation in their data set for the individuals from four different populations, African Americans, European Americans, Hispanic Americans, and Chinese Americans. I thought of the above census results when I saw the distributions on the plot: