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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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If you’re at ASHG, a session you might want to attend, Scale Effects and Recent Brain Evolution: Theory and Preliminary Evidence. Here’s the abstract:

What forces have driven human evolution since the grand human diaspora? In this paper, I argue that the scale effects so central to endogenous growth theory in the field of economics (e.g., Kremer’s widely-cited “Population Growth and Technological Change: 1,000,000 B.C. to 1990,” Quarterly Journal of Economics, 1993) have been important drivers of human brain development since the diaspora. Scale effects have made prominent appearances in recent explanations of continent-level outcomes. For instance, in Kremer’s model, big continents create larger, denser, faster-growing populations. In Diamond’s Guns, Germs, and Steel model, wide continents raise the chance that an innovation will arise at a given latitude, an innovation which can then disperse across that latitude, enriching those who live on wider continents. In both models, the Malthusian nature of pre-Industrial Revolution existence imposes strong conditions on the general equilibrium outcome. My model takes those channels as given, and works out the theoretical implications for the divergent evolution of human brains on these continents. Brains are biologically costly, so evolution will only select for larger brains if there is a substantial payoff. And since larger brains tend to have higher levels of intelligence [corr(Brain Size, IQ)= 0.4 in recent in brain-scan studies], larger brains tend to have more processing and memory power. Under certain parameter values, Kremer’s and Diamond’s models both imply that the payoff to a big brain—a brain that can better adopt someone else’s ideas—will be higher on wider, larger continents. Thus, we would expect human populations living on larger, wider continents to develop larger, more powerful brains. I model this relationship formally. This result should only hold on average: intra-group diversity is central to evolutionary theory, and massive intra-group diversity is an important fact of quantitative human genetics. The main purpose of the paper is to set forth the model, but I include some tests of its implications. I discuss whether, as the model predicts, human brain size and average IQ correlate positively with continent size and continent width. Indeed, evidence generally supports this hypothesis. Further empirical testing of the model’s predictions will occur as future researchers employ genetic diversity databases. I plan to present the results in a manner intelligible to non-economists.

Here’s the info:
Session Title: Evolutionary and Population Genetics Session

Session Location: Exhibit Hall II, Convention Center Session Time: Wed 9:30AM-3:30PM

Program Number: 643/W Poster Board Number:301 Presentation Time: Wed, Oct 21, 2009, 1:00PM-2:00PM

• Category: Science • Tags: Evolution, Human Biodiversity 
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The GSS variable GENENVO4:

Character, personality, and many types of behavior are influenced both by the genes people inherit from their parents and by what they learn and experience as they grow up. For each of the following descriptions, we would like you to indicate what percent of the person’s behavior you believe is influenced by the genes they inherit, and what percent is influenced by their learning and experience and other aspects of their environment. The boxes on handcard D1 are arranged so that the first box on the LEFT (which is numbered 1) represents 100% genetic influence (and 0% environment). The next box (numbered 2) represents 95% genes (and 5% environment), and so on. The RIGHTMOST box (numbered 21) represents 100% environmental influence (and no genetic influence). After each description, please type the number of the box that comes closest to your answer. Please use the numbered scale on handcard D1 to indicate, FOR EACH OF THE BEHAVIORS DESCRIBED, what percent of the person’s behavior you think is influenced by the genes they inherit, and what percent is influenced by their learning and experience. After each question, type the number of the box that comes closest to your answer. Remember, the higher the number, the more you think the behavior is influenced by learning and experience; the lower the number, the more you think it is influenced by genes 981. George is a Black man who’s a good all-around athlete. He was on the high school varsity swim team and still works out five times a week. (Please type in a number from 1 to 21):

In other words, if someone gives the response 1, they think that George’s athleticism is 100% a function of genes. 21, 100% a function of environment. The N for this variable is in excess of 2,000, and the question was asked in 2004. I decided to recode a bit so that responses were aggregated across 25% intervals like so: GENENVO4(r:1-6 “75% or more”;7-11 “50% or more”; 12-16 “25% or more”; 17-21 “less than 25%”). If you want to poke around the GSS you can just cut & paste that into the “ROW” box. I was surprised at some of the results, first, the lack of difference across ages, as well as the similarity between liberals and conservatives. On the other hand, the dumb and uneducated were more likely to put an emphasis on genes, which went along with my expectations. The data are below in table form, and as well as a line graph (just to show you visually which ones deviate from the others).

% Genetic All Whites Black Male Liberal Conserv No College Degree College Degree Dumb Average Smart
75-100 21.1 19.3 29.6 21 21.7 19.6 24.2 13.8 28.2 23 15.1
50-75 27.8 28.7 28 26.4 29.4 24.6 26.5 31.1 31.9 26.8 27.6
25-50 22.4 23.4 16.2 23.1 24.8 24.5 20.5 27.1 11.2 22.4 25.6
0-25 28.6 28.6 26.2 29.4 24.1 31.3 28.9 28 28.7 27.8 31.7

At first when I saw little difference between liberals & conservatives and across age groups I wondered if it was coded wrong. But the outcomes for intelligence & education seem to fit. Perhaps it has something to do with George being a black athlete, so the intelligent and educated know what they should say about this sort of question?

Note: Dumb = WORDSUM 0-4, average WORDSUM 5-7 and smart WORDSUM 8-10.

• Category: Science • Tags: Human Biodiversity 
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Neuroskeptic reviews new research which reports that East Asians and Europeans perceive facial expressions differently. Yes, differences do seem to exist, at least within the small sample studied, but there is a great deal of overlap. Of course much of the phenomena of interest are on the margins anyhow. Speaking of which, Genetic and Molecular Basis of Individual Differences in Human Umami Taste Perception:

Population diversities of SNPs in TAS1R1 and TAS1R3 have been reported by Kim et al…Minor allele frequencies of the SNP at 372 in TAS1R1 vary among eight populations; 10% in Cameroonian, 0% in Amerindian (native Americans), 25% in North European, 35% in Japanese, 5% in Russian, 35% in Hungarian, 40% in Chinese and 6% in Pakistani, whereas those at 757 in TAS1R3 showed no obvious difference among populations. These results suggest that there may be differences in umami sensitivity related with TAS1R1-A372T among populations in the world.

• Category: Science • Tags: Culture, Human Biodiversity 
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The Duffy-null state is associated with a survival advantage in leukopenic HIV-infected persons of African ancestry:

Persons of African ancestry, on average, have lower white blood cell (WBC) counts than those of European descent (ethnic leukopenia), but whether this impacts negatively on HIV-1 disease course remains unknown. Here, in a large natural history cohort of HIV-infected subjects we show that although leukopenia…was associated with an accelerated HIV disease course, this effect was more prominent in leukopenic subjects of European than African ancestry. The African-specific -46C/C genotype of Duffy Antigen Receptor for Chemokines (DARC) confers the malaria-resisting, Duffy-null phenotype, and we found that the recently described association of this genotype with ethnic leukopenia extends to HIV-infected African Americans (AA). The association of Duffy-null status with HIV disease course differed according to WBC but not CD4+ T cell counts, such that leukopenic but not non-leukopenic HIV+ AAs with DARC -46C/C had a survival advantage compared with all Duffy-positive subjects. This survival advantage became increasingly pronounced in those with progressively lower WBC counts. These data highlight that the interaction between DARC genotype and the cellular milieu defined by WBC counts may influence HIV disease course, and this may provide a partial explanation of why ethnic leukopenia remains benign in HIV-infected African Americans, despite immunodeficiency.

Duffy status is a highly ancestrally informative trait. This is a case where the relatively low between population variance found among humans does not apply. Rather, it seems that the Duffy null phenotype is a recent adaptation to malaria among West Africans. Because malaria has such a strong fitness implication many independent genetic adaptations have emerged, many of them with other negative side effects. On net individuals with side effects may still have higher fitness in an environment where malaria is endemic. Sometimes the net benefit is most evidence on a population wide scale, sickle-cell anemia is a deleterious homozygote which exists because of the much higher frequency of heteryzogytes vis-a-vis wild type homozygotes. Many malaria adaptations exhibit the large effect dynamic and suboptimal characteristic which one might except from the early stages of natural selection in a Fisherian model. You deal with the adaptive pressures of the present and let the future take care of itself. In this case, the future involved HIV:

The researchers found that leukopenia was generally associated with a faster disease progression from HIV to AIDS, independent of known predictors of AIDS development. “On average, leukopenic European Americans progressed nearly three times faster than their non-leukopenic African or European counterparts,” explained Hemant Kulkarni, MD, first author of this study. “However, leukopenic African Americans had a slower disease course than leukopenic European Americans, even though twice as many African Americans in the study had leukopenia.”

The investigators found that the DARC variation, not race, explained the differences in WBC counts in African Americans with HIV. Among those who were leukopenic, only those with the DARC variation experienced a significant survival benefit. Additionally, this survival advantage became increasingly pronounced in those with progressively lower WBC counts, suggesting that the interaction between DARC and WBC counts was the primary influence on slowing HIV disease progression in African Americans.

There are no doubt details in the genetic architecture of those with the null genotype worth future investigation.

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IQ Explains Some Of The Difference In Heart Disease Between People Of High And Low Socio-economic Status:

Authors of the study published in the European Heart Journal on 15 July…analysed data from a group of 4,289 former soldiers in the USA. They found that IQ explained more than 20% of the difference in mortality between people from socio-economically disadvantaged backgrounds compared to those from more advantaged backgrounds. Importantly, this was in addition to the classical, known risk factors for heart disease, such as smoking and obesity.

“The difference between the second and third analyses showed that IQ alone explained a further 23% of the differences in mortality between the higher and lower ends of the socio-economic spectrum, in addition to the other, known risk factors,” said Dr Batty. “IQ wasn’t a magic bullet in this study, but this psychological variable had additional explanatory power on top of the classic variables such as smoking, high blood pressure, high blood glucose and obesity. It has partially explained the differences in death from heart disease and all causes.”

…there could be three possible explanations for Dr Batty’s findings: “(i) intelligence might lead to greater knowledge about how to pursue healthy behaviours; (ii) intelligence may “cause” socioeconomic position, i.e. more intelligence leads to more education, income, occupational prestige . . .; and (iii) intelligence may be a marker for something else, and it is that something else, early life exposures, for example, that leads to mortality.”….

When correlations between socioeconomic status and health outcomes emerge, generally there is an assumption that the differences are due to disparate access to health care, or, more vaguely to the mysterious effect of low social status on someone’s health. Matt Ridley actually posited the second explanation in Genome. As noted above intelligence does not explain everything, but its role is unfortunately not considered all too often. If, for example, intelligence has some correlation with time preference, and time preference modulates one’s risk calculus, the causal chain which might result in disparate health outcomes is obvious. In The Myth of the Rational Voter Bryan Caplan has a reasonable number of references to the literature which show that the more intelligent may not be particularly rational in any absolute sense, but they are far more rational than the conventionally dull in a relative sense.

• Category: Science • Tags: Human Biodiversity, IQ 
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Look before you leap: Are women pre-disposed to be more risk averse than male adventurers?:

“It’s not at all that women are risk averse,” says Jody Radtke, program director for the Women’s Wilderness Institute in Boulder, Colorado. When men are confronted with challenging situations, they typically produce adrenaline, which is what causes them to run around, hollering like frat boys at a kegger. An adrenaline rush is a good feeling, but when confronted with the same situation, women produce a different chemical, called acetylcholine.

“Pretty much what (acetylcholine) does is it makes you want to vomit,” says Jody.

Because women don’t have the same positive chemical reward, they tend to be less pumped about confronting stressful situations. This leads them to rely on decision-making. Essentially, they want the whole picture before they go diving in.

Research, Jody says, shows women have more cross-networking between the two hemispheres of the brain, which subconsciously allows them to evaluate different sensory cues, facts and emotions when making decisions. The cause of this difference probably lies somewhere in the debate of nature versus nurture and the history of evolution.

Marvin Zuckerman, professor emeritus at the University of Delaware, has studied risk for decades. He found men are typically more likely to take risks when seeking novel or exciting sensations, and that comes from both genetics and environment.

What’s important seems to be the environment that isn’t shared by siblings in the same family,” he says.

The above was originally published by Women’s Adventure Magazine. The last reference is to the repeated finding that non-shared environment matters a great deal but isn’t well accounted for. Obviously both men and women vary in terms of psychological attributes, and there have been plenty of attempts to adduce the variation to different quantities of neurochemicals (the “chemical soup” model is easy to translate into prose).

The content of the piece isn’t too surprising, you see it all the time. Suggesting innate differences between men and women is totally acceptable so long as it is perceived to be neutral, or, better yet, casts women in a positive light. Michael Lewis’ recent article on the Icelandic financial turmoil hints to sex differences and male psychology as a root problem. He presented a rather conventional stereotype of men as financial cowboys willing to take outsized risks for reward, while women were risk averse socialists. During the run up to the Iraq War and afterward I recall many people, mostly but not always women, calling into Leftish radio shows promoting a sex determinist theory that war was the result of the male nature, and the fact that men are head of states of most nations was the ultimate problem (this argument crops up in science fiction as well).

The interesting point to me is the sort of articles which highlight “different ways of thinking” between the sexes and how they might be rooted in biological differences have implications which point in different directions in terms of positive or negative valuation depending on your perspective and circumstance. As a specific example, the risk taking predispositions of many males can be seen to be folly and lack of prudence, but, risk often entails both an upside and a downside. Decisions which may seem foolish and wrongheaded viewed through a conventional mainstream lens are often lauded in hindsight as visionary. Unfortunately the nature of uncertainty is such that one has little idea which risks will pay off and which will simply extract a downside cost. It is likely that human societies dominated by those who are only risk averse, or those who are only risk accepting, would not be those which we would truly wish to live in. Variation in human personalities is probably beneficial in an aggregate sense when it comes to human progress. There are downsides risks to both the risk averse and risk accepting strategy, so it is probably best to have some of both. In an economic scenario what I’m talking about is straightforward; consider two individuals with degrees in computer science, one who goes to work for IBM and another who founds a start-up. You wouldn’t want everyone to aspire to become a corporate employee, where would the innovation which drives productivity growth come from? On the other hand, there are only so many start-ups which succeed and there is a need for individuals who work in less sexy sectors who service older established technologies which are at the heart of the current economy. In other words, you want to be able to squeeze more juice from the oranges you have, as well be funding research which might result in the discovery of jucier varietals.

Addendum: Obviously what I’m saying here isn’t too novel. It’s rooted in human nature itself: our minds are cobbled together from disparate competencies and subfunctions, and our unitary consciousness is a delusion very successfully promoted by the prefrontal cortex. But even when it comes to concepts and assumptions which are the purview of the prefontal cortex its priority isn’t usually to keep its story straight. Rather it seem geared toward generative ad hoc narratives which are only proximately consistent. Yes it can engage in rationality, but most of the time its forte is rationalization. And why not? Rationalizing the contradictory feels good! It was almost certainly highly adaptive in the past, and likely is today, in terms of keeping everyone in the group on the same page.

• Category: Science • Tags: Genetics, Human Biodiversity, Sex Differences 
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Serotonin Transporter Genotype Modulates Social Reward and Punishment in Rhesus Macaques (paper is OA, so click through for stats & charts):

Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonin transporter gene (5-HTTLPR) has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans.

In contrast to monkeys with two copies of the long allele (L/L), monkeys with one copy of the short allele of this gene (S/L) spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a “pay-per-view” task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos.

ScienceDaily has an interesting tidbit:

In a series of experiments, the S version of the gene in monkeys was found to influence their risk-taking when faced with particular social stimuli.

“Based on work in humans, we interpreted this to reflect an induction of a fearful emotional state, which often leads people to become risk averse,” said Karli Watson, Ph.D., of the Duke Department of Neurobiology, lead author on the paper.

In human populations of European ancestry, 48% are S/L and 36% are L/L. The rest are S/S. The S allele is more common in Asian populations, Watson noted.

More on 5-HTTLPR.

• Category: Science • Tags: Human Biodiversity 
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Everyone & their mother is emailing me about Jonathan Haidt’s new commentary in Edge, FASTER EVOLUTION MEANS MORE ETHNIC DIFFERENCES:

I believe that the “Bell Curve” wars of the 1990s, over race differences in intelligence, will seem genteel and short-lived compared to the coming arguments over ethnic differences in moralized traits. I predict that this “war” will break out between 2012 and 2017.

There are reasons to hope that we’ll ultimately reach a consensus that does not aid and abet racism. I expect that dozens or hundreds of ethnic differences will be found, so that any group – like any person -Â can be said to have many strengths and a few weaknesses, all of which are context-dependent. Furthermore, these cross-group differences are likely to be small when compared to the enormous variation within ethnic groups and the enormous and obvious effects of cultural learning. But whatever consensus we ultimately reach, the ways in which we now think about genes, groups, evolution and ethnicity will be radically changed by the unstoppable progress of the human genome project.

Yes, psychopathy might have adaptive “strengths” in a frequency dependent context, but I don’t think that’s what Haidt meant! One difference with the IQ wars when it comes to personality is that it seems every single dopamine receptor has already been implicated in behavior genetic variation, while we’re still a long way from IQ loci results which have been reproduced, though one might double-check on the details of the statistical analyses on suggestive findings from behavior genetics. In any case, since the heritability of behavior in economic games has already been established, it would be interesting if GWAs found some loci which tracked the variation. My own hunch is that personality variation is less continuous than IQ (characterized by a few morphs hanging around fitness peaks), with an underlying architecture of larger effect QTLs. Perhaps altruism is just way simpler to modulate than general intelligence?

• Category: Science • Tags: Human Biodiversity 
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• Category: Science • Tags: Human Biodiversity 
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Post-Columbian population movements and the roots of world inequality:

Why should we care about the apparently powerful influence that population origins exert on country and sub-national incomes levels?

First, if this influence is indeed as significant as our findings suggest it to be, then efforts to sort out the roles that geographic, institutional, and other factors play in explaining income levels and growth rates may produce misleading results unless we properly control for it.

Second, the influence of population origins suggests that there is something that human families and communities transmit from generation to generation — perhaps a form of economic culture, a set of attitudes or beliefs, or informally transmitted capabilities — that is of at least similar importance to economic success as are more widely recognized factors like quantities of physical capital and even human capital in the narrower sense of formal schooling. If we understand which culturally transmitted factors are important and what contributes to their emergence and propagation, we might be able to design policy interventions that could help less successful groups and countries to close their developmental gaps.

Also, Ancestors and incomes: More on the roots of world inequality. I don’t doubt all sorts of implicit cultural norms, information, etc., are transmitted from generation to generation. But there’s also something else which is passed from generation to generation which might come to mind….

• Category: Economics, Science • Tags: Economics, Human Biodiversity 
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Steve has a modestly titled post up, Height and Weight, where he analyzes data from Anthropometric Reference Data for Children and Adults: 2003-2005 (PDF). This is government data on American men, women and children who are Non-Hispanic White, Non-Hispanic Black and Mexican American. I invite readers to peruse the raw data themselves. Steve did a little comparison of various parameters for males and females of the three populations. I thought it would be illustrative to plot the distributions of some the metrics so as to illustrate more intuitively the variation within the populations (the X axis are percentiles). Half Sigma pointed to Steve’s post, and the discussion is unsurprisingly vibrant. I think it’s safe to assume there is “structure” in something like weight within these populations due to geography and SES. You can see this even in New York City, just start from Bergdorf Goodman (especially around the Holidays) and walk north and east into the Upper East Side. Mean BMI starts dropping. In any case, like Steve I thought focusing on the 20-39 demographic was convenient, in part due to the nature of the readership of this weblog. Here’s the CDC’s BMI Calculator.

The data I used is here.

• Category: Science • Tags: Health, Height, Human Biodiversity 
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Distance from Africa, not climate, explains within-population phenotypic diversity in humans:

The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan Africa. Using a large database of male and female skull measurements, we apply an explicit framework to quantify the relative role of climate and distance from Africa. We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity, while climate plays no role. By selecting the most informative set of traits, it was possible to explain over half of the worldwide variation in phenotypic diversity. These results mirror those previously obtained for genetic markers and show that ‘bones and molecules’ are in perfect agreement for humans.

The use of skull-traits is a little 1930s…but a trait is a trait. For you anatomy nerds (of which, I am not one), the list of traits is below the fold. And no, cephalic index is not on the list….
1. Maximum cranial length (GOL)
2. Nasion-opisthocranion (NOL)
3. Cranial base length (BNL)
4. Maximum cranial breadth (XCB)
5. Minimum frontal breadth (M9)
6. Maximum frontal breadth (XFB)
7. Biauricular breadth (M11)
8. Biauricular breadth (AUB)
9. Biasterionic breadth (ASB)
10. Basion –bregma height (BBH)
11. Sagittal frontal arc (M26)
12. Sagittal parietal arc (M27)
13. Sagittal occipital arc (M28)
14. Nasion-bregma chord (FRC)
15. Bregma-lambda chord (PAC)
16. Lambda-opisthion chord (OCC)
17. Basion prosthion length (BPL)
18. Breadth between Frontomalare temporale (M43)
19. Bizygomatic breadth (ZYB)
20. Middle facial breadth (M46)
21. Nasion prosthion height (NPH)
22. Interorbital breadth (DKB)
23. Orbital breadth (M51)
24. Orbital breadth (M51a)
25. Orbital height (OBH)
26. Nasal breadth (NLB)
27. Nasal height (NLH)
28. Nasal height (M55)
29. Palate breadth (MAB)
30. Mastoid height (MDH)
31. Mastoid width (MDB)
32. Breadth between Frontomalare orbitale – Frontal chord (M43(1))
33. Frontal subtense (No 43c)
34. Minimum horizontal breadth of the nasalia (sc) – Simotic chord (M57, WNB)
35. Simotic subtense (No 57a, SIS)
36. Breadth between zygomaxillare anterius – Zygomaxillary chord (M46b, ZMB)
37. Zygomaxillary subtense (No 46c, SSS)

• Category: Science • Tags: Human Biodiversity 
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I really don’t have much to add that’s original, I’ve long tired of the “definition wars.” Early this year Steve wrote a column rebutting some criticisms that Malik makes of his definition of race in Strange Fruit: Why Both Sides are Wrong in the Race Debate. The book is out in the United States now…I’m halfway through it, and there’s nothing new to anyone who reads this weblog. The fundamental problem is that it is too easy to use the statistical inferences which are generated by human population genetics as a launching point for a thousand verbal shell games. Like the species concept debate I think pragmatists are well advised to be instrumentalists.

Here is what L. L. Cavalli-Sforza said 2 years ago after I asked him about Lewontin’s Fallacy:

Edwards and Lewontin are both right. Lewontin said that the between populations fraction of variance is very small in humans, and this is true, as it should be on the basis of present knowledge from archeology and genetics alike, that the human species is very young. It has in fact been shown later that it is one of the smallest among mammals. Lewontin probably hoped, for political reasons, that it is TRIVIALLY small, and he has never shown to my knowledge any interest for evolutionary trees, at least of humans, so he did not care about their reconstruction. In essence, Edwards has objected that it is NOT trivially small, because it is enough for reconstructing the tree of human evolution, as we did, and he is obviously right.

In other words, between group differences may be both small and important. Whether this is so is an empirical matter.

• Category: Science • Tags: Human Biodiversity 
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Asian-White IQ variance from PISA results:

The NE Asians performed about .5 SD better on average (consistent with IQ test results), and exhibited similar (slightly higher) variance.

Interestingly, the Finns performed quite well on the exam, posting a very high average, but their SD is slightly smaller. The usual arguments about a (slightly) “narrow bell curve” might apply to the Finns, but apparently not to the NE Asians.

Read the whole post to see if you follow the logic of the inferences; I’ve done some digging on this before to spot check the Europeans-higher-variance meme and didn’t find much to support it, and some data to disprove it (though you could explain away that data because of clumping of distinct populations, etc.). That’s the main reason I get irritable whenever this meme pops up in the comments, it’s one of those “facts” which exhibits circular citation dynamics and spreads like wildfire. Of course, it isn’t as if the meme is totally emerging out of a vacuum: if East Asians are so smart why aren’t they as scientifically creative??? It seems to me that the most plausible explanation has to be that individual intelligence isn’t sufficient for intellectual creativity, though it is likely a necessary precondition. Some of the other variables might be rooted in individual psychology (personality), but I suspect others manifest on a larger scale (e.g., the top-down paternalism and emphasis on conformity which is the norm in most East Asia societies).

• Category: Science • Tags: Human Biodiversity, IQ 
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My friend Jake Young has a post up, Contrasting Views on the Gender Disparity in Science:

Second, one of my primary arguments against innate differences in ability between men and women is that you are dealing with traits that have distributions and those distributions largely overlap. Making a statement about any individual man or woman is largely useless. The odds of a women or man selected at random being better or worse at math are not particularly different. This argument applies just as well to differences in preference. Maybe there are differences on average, but they are still distributions that overlap. The key question becomes: to what degree do those distributions overlap? How different on men’s and women’s preferences on average?

James Crow’s Unequal by nature: a geneticist’s perspective on human differences is apropos here:

There is actually a simple explanation that is well known to geneticists and statisticians, but not widely understood by the general public or, for that matter, by political leaders. Consider a quantitative trait that is distributed according to the normal, bell-shaped curve. IQ can serve as an example. About one person in 750 has an iq of 148 or higher. In a population with an average of about 108 rather than 100, hardly a noticeable difference, about 5 times as many will be in this high range. In a population averaging 8 points lower, there will be about 6 times fewer. A small difference of 8 points in the mean translates to severalfold differences in the extremes.

My conclusion, to repeat, is that whenever a society singles out individuals who are outstanding or unusual in any way, the statistical contrast between means and extremes comes to the fore. I think that recognizing this can eventually only help politicians and social policymakers.

• Category: Science • Tags: Human Biodiversity 
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PULITZER WINNER: Harmon of ‘NYT’ Studied DNA After Birth of Child . Recall that Harmon interviewed a contributor to this weblog as well as Half Sigma for a recent article.

Via Jonathan Eisen.

• Category: Science • Tags: Human Biodiversity 
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Just got a note from someone I trust that a massive QTL for IQ has been discovered, on the order of 10 points in effect for a substitution of the the major allele for the minor (it’s additive and independent, so homozygote minor allele ~ 20 points greater than homozygote major allele). The novel variant is found in an ethnic-religious minority population and no other phenotypic effects are discernble for those who carry the IQ boosting polymorphism. Everything is very preliminary at this point…but they’ve checked and re-checked and this seems to be real. There are two genes previous implicated in neurological pathologies in this region of the genome, so a molecular genetic & physiological story should be easy to extract.

I’m being a little vague on the details for obvious reasons; no one wants to be scooped. But word is spreading through the labs though, so my friend thought it might be good to prep the public and those at GNXP who are interested in this topic. Expect a Nick Wade article as soon as possible. Exciting times….

Update: Yes, April Fool’s. Obviously I wasn’t going to do something like taking down the site and pretending someone was going to sue us; you might recall that several GNXP readers sent the befuddled sysop of the Gene Expression Omnibus some irate emails….

• Category: Science • Tags: Human Biodiversity, IQ 
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About a year ago a paper came out, Low Levels of Genetic Divergence across Geographically and Linguistically Diverse Populations from India. The authors used Asian Indian groups from the United States, ergo, the caste/class representativeness is not is very typical. Additionally, there is a strong skew to Gujaratis since this group represents 1/2 of American Asian Indians. One could offer the reasonable opinion that the low amount of between population variance is simply a function of the fact that higher status groups across South Asia are not particularly differentiated from each other. I don’t have a final opinion, but I would be moderately skeptical of this because I’ve seen enough work in the past suggesting that Brahmins, for example, are not particularly closely related to each across regions (and many of these regional Brahmin groups show strong evidence of gene flow with other local caste groups, though there usually there is some differentiation).

In any case, that’s just a preface to the fact that a provisional paper has come out from the same group, Prevalence of common disease-associated variants in Asian Indians. If you’re interested in the topic of the paper, all I have to say is that it seems that the major inference one might make is that more studies need to be done with Asian Indians because they likely have a whole lot of population-specific disease variants which aren’t well known yet. Human biodiversity has some practical medical implications. But that’s not what I want to focus on. In Table 4 they have some data on frequency of the minor frequency allele on SLC24A5, which in the case of South Asians is the ancestral variant. That is, the allele which is fixed in Africans and East Asians, and absent in Europeans, is the one shown in the table.

Language N Frequency of ancestral allele
Assamese 26 0.260
Bengali 27 0.293
Gujarati 181 0.208
Hindi 29 0.105
Kannada 24 0.268
Kashmiri 24 0.020
Konkani 43 0.058
Malayalam 25 0.259
Marathi 26 0.296
Marwari 25 0.041
Oriya 27 0.154
Parsi 25 0.100
Punjabi 28 0.052
Tamil 29 0.036
Telugu 28 0.000

There’s nothing that surprising here. I wouldn’t take some of the frequencies as scripture; I suspect that some of these linguistic groups are not representative (the frequency for the Gujaratis I can believe since I’ve seen it elsewhere, while the northwestern groups are in line with the ones from the HGDP populations). It seems likely that a strong NW-SE cline on the variation of this gene exists just as it does on many genes in South Asia. There is data which shows that in Sri Lanka the frequency of the ancestral allele is 0.75 for Tamils, and 0.50 for Sinhalese. I wouldn’t read too much into these data either; but I’ve seen results elsewhere which would imply that you shouldn’t be surprised at seeing a ancestral allele frequency around ~0.25 for South Asians on SLC24A5. I know this is a provisional paper, and this might get yanked, but I want to point this out:

The MAF [minor allele frequency] for the SLC24A5 g.13242G>A polymorphism [the ancestral allele] (0.114) in the Indian population is closer to that of Caucasian European populations (0.000-0.020) than to that of East Asians (0.979-0.989) and Africans (0.730-0.980)…This is surprising given that, as a whole, people of Indian origin have darker skin tone compared to Europeans. The East Asian and African populations share a similarly high frequency of the minor allele of the SLC24A5 g.13242G>A SNP, which in itself is surprising as East Asians are typically of much lighter skin than Africans. It is also interesting that the t-test suggested a greater similarity in MAF between Indians and those of populations in the Americas (Puerto Rican, Mexican, and Amerindian), who are of a similar skin tone….

No shit it’s surprising. We know that SLC24A5 polymorphism can account for about 1/3 of the skin color variation in South Asians. It isn’t as if it doesn’t affect skin color in this population due to some modifier locus. The frequencies of SLC24A5 alleles in Latin American populations is just a proxy for European and non-European admixture; the non-European groups in Latin America are Amerindians and Africans, both of whom tend to carry the ancestral variant.

In any case, contrary to the impressions of those of you who only know of South Asians from Bollywood, Indians are on average darker-skinned than Puerto Ricans or Mestizos. SLC24A5 has been under selection within the last 10,000 years. It explains 25-40% of the between group difference in complexion of Europeans and Africans (checked via an admixture study with African Americans). But there’s no way I think that light skin was being selected in southern India within the last 10,000 years. Something else is going on….

• Category: Science • Tags: Human Biodiversity 
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Most of you probably know about the “species problem.” The short of it is that even though the level of the species is probably the most justifiable one within the hierarchy of taxonomic systems (as opposed to say genus or order), it is not a cut & dried category. I tend to agree with evolgen that the nature of the species concept you use is going to be guided by instrumental concerns. If you are are focused upon taxonomy I have no doubt that the phylogenetic species concept is the bomb. On the other hand, if you are an evolutionary geneticist interested in speciation the details of the structure of the tree of life is less important. You would be more interested in how the branching occurs, in which case the biological species concept and its cousins are of more relevance. During the 18th and 19th century some taxonomists argued that their discipline had a claim to being the Queen of Sciences precisely because it was window into the mind and intentions of God’s Creation. For these pre-evolutionary thinkers there was a religious and metaphysical significance in species; inappropriate classification would have distorted God’s intent and obscured the grand beauty of his plan. Today we don’t species aren’t loaded with some metaphysical importance; our conception of the world does not hinge upon the battles between lumpers & splitters.

Which brings me to a lower taxonomical category; that of race. Or whatever you want to call it, you know what I mean! Obviously over the years on this weblog we’ve put the spotlight on specific issues such as Lewontin’s Fallacy, which though seemingly abstruse can resolve confusions and misinformation being perpetuated in other domains. We’ve also pushed into more controversial territory like between group differences in behavioral tendencies & IQ, as well as less radioactive topics such as tissue matching problems across populations for transplantation. There’s a lot of ground over the past 5+ years. But I believe there are 4 primary dimensions of variation, which though related (they aren’t really orthogonal), get at different concerns.

1) First, there’s the phylogenetic/total genome content angle. This is simply a form of Steve Sailer’s race is an extended family argument. The tens of thousands of genes an individual has all exhibit their own distinct phylogenies; but they’re not totally independent as a practical matter. We don’t live in a perfectly panmictic world, population substructure is real. Just open up History and Geography of Human Genes; the classical autosomal markers exhibit correlations, which allow one to make assertions about population histories and relationships.

2) Second, there are the functional loci under selection. The story of lactase persistence in Europe & Asia is the best illustration of what I’m talking about here. From the North Sea to the Punjab a haplotype which likely arose around the Volga region has swept to high frequency within the last 10,000 years because of gene-culture coevolution. If you look at most other markers Middle Eastern populations will be closer to Europeans than peoples from the Punjab in northwest India (see the Fst values in History and Geography of Human Genes for example). But not on this locus. In fact, on this locus Danes are closer to Punjabis than they are to Sicilians, on average!1 Though most recently selected alleles will not break the cladograms you derive from neutral markers to ascertain phylogenetic relationships of populations, there will be plenty of peculiarities on the margins, and I have argued that these deviations are not trivial to our understanding of the history of the shape of human variation. Who can deny that the nature of genetic variation (or lack of) of indigenous New World groups was not of particular importance in relation to Old World people as a whole, as opposed to the undoubted phylogenetic reality that New World native peoples were a subset of East Asian Siberian populations.

3) This brings me to the dimension of salient phenotypic traits. No need for complex exposition of what I mean about this. Insofar as one looks at total genome content Melanesians are closer to the peoples of East Asia than they are to those of Africa. But if most people in the world were shown portraits of individuals from these three groups, and asked to generate an outgroup, I think most would assume that East Asians differed from the other two groups more than either did from each other. This is not to say that Melanesians and Africans look the same, or that Melanesians and Africans do not exhibit a great deal of within group variation in physical appearance, it is simply that the human brain strong affected by particular characteristics when generating classifications. Folk biology has a universal rationale, and is shaped by innate biases. Skin is our largest organ, and it is something that we as humans notice because there are strong adaptive reasons to scrutinize the skins of our conspecifics (fitness, disease, a rough & ready ascertainment of age). I agree with Steve Sailer that the monomanical focus on skin color which reigns in the American social discourse on race is a bit ridiculous, but I also think it is entirely expected and reasonable that skin color would loom large in any folk racial classification system. Many of the peoples which Europeans during the Age of Discovery encountered were referred to as “blacks.” They were very different from each other, and Europeans recognized this. Today we know that all the non-African blacks are genetically closer to Europeans than they are to African blacks (who are characterized by a great deal of within group population substructure as well), but it is no surprise that a skin color terminology came to the fore. The West & Central Asian Muslims who ruled India during the medieval and early modern periods referred to themselves as white, and the natives as black. The Chinese would sometimes refer to the Khmer peoples as black as well, because that was a salient contrast. Of course other traits were recognized, and there is also a long tradition of Europeans suggesting that the peoples of South Asia were not truly black, but rather a very pigmented form of their own kind due to similarities of hair form and facial features. This sort of counter-argument was aided by the fact that a non-trivial proportion of South Asians even exhibit a brunette white complexion (usually along the northwest fringes).

4) This brings me to the last of the major ways in which we perceive human variation, and that is through the socially biased and constrained lens. Obviously this is affected by and contingent upon #3 to a great deal, but the boundary conditions are ill
ustrative. In high school I was taking calculus with a friend whose mother was Scottish American and father was a Palestinian Arab. His name was an Arab one, but his physical appearance is by any definition “white.” His skin is white, his hair is brown, his eyes hazel, and his features favored his Scottish as opposed to Levantine side (I had a 1/4 Lebanese friend who had a more recognizable Arab visage). Another friend, who was of vanilla Anglo origin as most of my classmates were, observed that we were the only two non-whites in the class, referring to myself and my aforementioned friend. Here’s the irony: by any standard my Anglo friend was darker than my non-white friend, he had dark brown eyes, dark brown hair, and less of a pink pallor to his complexion. I recall kind of laughing at that assertion, and the teacher bitched me out about being disruptive and I laughed again. The point here is that the idea that taxonomical perceptions are colored by power hierarchies is not totally incorrect! In fact, it seems trivially obvious. I’ve been reading a fair amount on the Chinese & Japanese interaction with Western powers between 1500-1800. It is interesting that in the earlier commentaries on Asian peoples many Europeans observed that the Chinese and Japanese were white, unlike the peoples of South or Southeast Asia. After the last wave of Sinophilia receded after the mid-18th century there was a noted shift toward a perception of East Asians as being non-white. In other words, the whiteness of East Asian peoples (even if that whiteness was a different kind) inversely tracked the European sense of superiority to them.

I think #1 and #4 are pretty easy to understand. Thinking of race as an extended family simply co-opts our native intuitions about genealogical relations. In other words, it’s an extension of preexistent software. As far as #4 goes, there’s enough pointers from the current academic dispensation that we can comprehend the nuances. The main point is to map the dynamics more accurately upon reality and not elide the complexities inherent within socially constructed categories which are only partly informed by folk biology. A tendency to pretend as if whites and non-whites are the only two relevant categories prevents the acknowledgment of the realities of how various groups relate to each other (e.g., the social science data which suggests most American non-white groups prefer whites to other minorities).2 Since #3 is derived pretty directly from folk biology and some gross social cues it isn’t too difficult. It’s the practical definition of human variation which people in the United States have in their head.

#2 is a tricky one. I think it’s really the most interesting one at this point, but I don’t know how to really communicate it to people outside of a more technical framework. Alluding to selective sweeps and QTLs of large effect seems kind of important. #3 is actually a visible subset of this, and so I think when it comes to the general concept of how a functional locus may not reflect the evolutionary history of the whole genome that’s a good place to start. LCT is also important, it’s very well elucidated in all sorts of ways and so you can speak with confidence. Skin color is also a good case because people are generally aware of the trait and the general outline of inheritance patterns, and its putative adaptive significance. A lot of the work on recent human evolution is related to this dimension, so I think it’s important for intelligent people to keep this angle in mind.

The main issue is not to conflate the various facets of human variation. There are ideological reasons that people will privilege one or the other, but in terms of utility that depends on where you stand. I’m obviously pretty interested in questions and issues where #2, to some extent #1 and #3, are very operationally the relevant background definitions. #4 is not something I deny, but it’s not particularly interesting to me, nor does it speak to the questions I’m focused on. #4 has come to the fore with the ubiquity of international trade and travel, along with a host of social and political movements. That’s all real, and it’s all significant, but it isn’t really normally part of my brief. It intersects with my interests only a specific case of psychological issues, or an indicator of social dynamics.

1 – By this I simply mean that if you draw a random Sicilian, Dane and Punjabi, and are asked to predict which group will be the outgroup when it comes to the most recent common ancestor on the locus LCT, it would be the Sicilian. On most of the other loci, it would be the Punjabi.

2 – I recall listening to a radio show about tensions between South Asians and people of black African origin. Several white callers were shocked and outraged, and asserted that such tension and racial antogonism between non-white groups was by definition ludicrous and incoherent. Both groups were non-white, ergo, they had common interests by definition. There’s a little bit of the sense that some whites view non-whites as objects which only operate within the bounds of some deterministic framework, as opposed to conscious agents who act in response to specific conditions and their own perceived self-interest.

• Category: Science • Tags: Human Biodiversity 
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"