New Paper: Genetic diversity and emergence of ethnic groups

Posted by Greg Laden on September 2, 2009
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A new study using both genetic and cultural data shows that ethnic groups in Central Asia are primarily a sociocultural phenomenon.

From the Abstract:

…we used genetic data that … in addition to data from the literature, to understand better the origins of Central Asian groups at a fine-grained scale, and to assess how ethnicity influences the shaping of genetic differences in the human species. We assess the levels of genetic differentiation between ethnic groups on one hand and between populations of the same ethnic group on the other hand …

Our results show that there are more differences between populations of the same ethnic group than between ethnic groups for the Y chromosome, whereas the opposite is observed for mtDNA in the Turkic group. This is not the case for Tajik populations belonging to the Indo-Iranian group where the mtDNA like the Y-chomosomal differentiation is also significant between populations within this ethnic group. Further, the Y-chromosomal analysis of genetic differentiation between populations belonging to the same ethnic group gives some estimation of the minimal age of these ethnic groups. This value is significantly higher than what is known from historical records for two of the groups and lends support to Barth’s hypothesis by indicating that ethnicity, at least for these two groups, should be seen as a constructed social system maintaining genetic boundaries with other ethnic groups, rather than the outcome of common genetic ancestry.

Our analysis of uniparental markers highlights in Central Asia the differences between Turkic and Indo-Iranian populations in their sex-specific differentiation and shows good congruence with anthropological data.

ResearchBlogging.orgTo the extent that ethnicity can be seen as parallel to, equal to, or nascent racial groupings, this is evidence supporting the model that for the most part distinct racial groups are genetic unicorns even if they are hard and stark realities in the political and social world. This is not to say that genetic variation does not exist or that it is not (somewhat) meaningful, especially with respect to understanding historical factors. But, the race-based model of correlated alleles that allow an observer to place a person in an ethnic group and then predict invisible features (like IQ, criminality, math ability, etc) is brought into serious question.

The study concludes:

Since the work of Frederik Barth in the 1970s [12] anthropologists have placed emphasis not only on presumed common ancestry and shared cultural traits, but also on the “boundaries” used by individuals in order to distinguish themselves from members of other ethnic groups. These boundaries can take different forms – racial, cultural, linguistic, economic, religious, and political – and may be more or less porous. The persistence of such boundaries implies rules. One of the most common rules around the world is an endogamous preference for mate choice. In conclusion, our analysis of uniparental markers lends support to Barth’s hypothesis by indicating that ethnicity, at least for two (and marginally three) of the Turkic groups in Central Asia, should be seen as a constructed social system maintaining genetic boundaries with other ethnic groups rather than the outcome of common genetic ancestry.

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Barth F: Ethnic groups and boundaries. The social organization of culture difference. (Results of a symposium held at the University of Bergen, 23rd to 26th February 1967.). Bergen, London: Universitetsforlaget;Allen & Unwin; 1969.

Heyer, E., Balaresque, P., Jobling, M., Quintana-Murci, L., Chaix, R., Segurel, L., Aldashev, A., & Hegay, T. (2009). Genetic diversity and the emergence of ethnic groups in Central Asia BMC Genetics, 10 (1) DOI: 10.1186/1471-2156-10-49

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  1. #1 Sigmund
    September 2, 2009

    This paper seems rather strange in comparison to most population genotyping studies done of late. Why did they not examine multiple markers using a SNP chip, for instance, rather than simply looking at mitochondrial and Y chromosomal markers?
    As for your point:
    “But, the race-based model of correlated alleles that allow an observer to place a person in an ethnic group and then predict invisible features (like IQ, criminality, math ability, etc) is brought into serious question.”
    What model is this?
    I haven’t seen this suggested as a serious model by anyone important in the field of population genetics.
    I’m not even sure the writers of the highly dubious Bell Curve went as far as that.

  2. #2 travc
    September 2, 2009

    SNP chips are pretty damn expensive, especially in the quantities needed to do population genetics. Plus, if you are using a commercial SNP chip (not designing your own, which is very very expensive) then you have to identify markers segregating between the sub-populations of interest on the sex-linked regions… a not inconsequential project unto itself.

    SNP chips (and tiling arrays) are cool, but they aren’t (yet) well suited for a lot of population genetics. It is all about screening populations after all. When costs come down that is likely to change.

    I don’t know humans all that well, but it seems likely there are established markers for these populations already. Someone has probably already designed the primers and protocols for doing molecular tests (probably using parallel PCR techniques) which are cheap and fast enough to screen large numbers of samples.

  3. #3 Greg Laden
    September 2, 2009

    I haven’t seen this suggested as a serious model by anyone important in the field of population genetics.

    So, you don’t consdider James Watson to be important? Well, he’s not really a population geneticist I suppose….

    But anyway, yes, I agree that this sort of bald faced misconception is not commonly found among smart people who know about genetics. That is, of course, a small percentage of scientists in general and an infinitesimal percentage of the rest of the species.

    I’m not even sure the writers of the highly dubious Bell Curve went as far as that.

    Well, I’m quite sure of what they said. They make no biological argument whatsoever. They say that there are groups of people that have certain characteristics, but it is not their job or area of expertise to know how it ended up that way. They just accept the ‘reality’ as it is. Then, they include what essentially is an abridged version of J. Philippe Rushton’s racist book as an appendix and point to that. As authors of the book, then, they are essentially making the claim I refer to here but trying to have it both ways and pretend they are not at the same time.

  4. #4 Vince Whirlwind
    September 2, 2009

    Hang on, am I the only one having trouble with this?

    What is the difference between “visible features” and “invisible features” apart from their visibility? If ANY feature *is* determined by genes – visible or not! – then genetic divergence between populations may result in population-based difference predictability in those features – visible or not!

    If you go to Sweden, Watson could predict you might find a lot of people with a gene expressing blonde hair.
    If you go to China, Watson could predict you might find very few people with a gene for lactose tolerance.

    As for IQ – let’s see the alleles that determine IQ, first, before we agree there can be a model for prediction…for the moment all we know is that there is an uneven geographic distribution for IQ which seems to correlate quite well with poverty.

    Interesting research published the other day found a negative correlation between obesity and IQ. Could be the poverty thing again…

  5. #5 NewEnglandBob
    September 2, 2009

    Mumble-what?

  6. #6 Greg Laden
    September 2, 2009

    negative correlation between obesity and IQ. Could be the poverty thing again…

    Are you referring to the brain shrinkage research? If so, that is not very applicable here. Pathologies are important but not useful except as clues in thinking about evolutionary patterns.

  7. #7 MadScientist
    September 3, 2009

    Perhaps the most bizarre demarcation I’d seen (and the news calls it ‘ethnic’ although it is religious) is the distinction between Serbs and Croats and muslims and christians in that region. As the brother of a Bosnian friend remarked “we’re the same fucking people; I don’t know why we’re so keen to kill eachother”.

  8. #8 Sigmund
    September 3, 2009

    “I haven’t seen this suggested as a serious model by anyone important in the field of population genetics.”

    “So, you don’t consdider James Watson to be important? Well, he’s not really a population geneticist I suppose….”

    He’s not, but if he actually proposed a serious model along the terms of your original statement then I would certainly concede the point.
    Correct me if I’m wrong here Greg but I got the distinct impression that the Watson incident was not one of a scientist proposing a serious model but rather one of a scientist making a remarkably stupid offhand racist comment that he immediately disavowed when it was publicly reported.

  9. #9 toto
    September 3, 2009

    But, the race-based model of correlated alleles that allow an observer to place a person in an ethnic group and then predict invisible features (like IQ, criminality, math ability, etc) is brought into serious question.

    Would.

    The “groups” considered in this study are all very close ethnically and geographically. Colour me not surprised that they didn’t find much between-group genetic distance.

    When you increase the scope, the fact that there exists correlated allele differences between people from vastly different origins is neither surprising, nor controversial. It’s an established fact. If they didn’t, they wouldn’t show up as highly separated clusters on PCA graphs. (Of course that doesn’t mean it should automatically result into genetic behavioural differences.)

    (and the news calls it ‘ethnic’ although it is religious)

    I guess “ethnic” really means anything that allows people to distinguish an “us” from a “them”. Religion in this case is just one such marker. As Dawkins pointed out, the combatants in the Yugoslav wars were not trying to settle a theological point. They were trying to gain territory from (or cleanse their own territory from) “the other”. Such are we.

  10. #10 Chi
    September 7, 2009

    Sigmund,

    What exactly do you disagree with about Watons’ comment?

    1. “He says that he is “inherently gloomy about the prospect of Africa” because “all our social policies are based on the fact that their intelligence is the same as ours – whereas all the testing says not really”, and I know that this “hot potato” is going to be difficult to address.

    Does the testing not say this? It seems quite clear that Watson is correct about the testing showing that. See the Snyerman/Rothman survey (preferably read the book which goes into great detail on the issue) on the views of 661 members of the Behavioural Genetics & American Psychological Associations.

    http://www.gnxp.com/blog/2007/10/james-watson-tells-inconvenient-truth_296.php

    2. His hope is that everyone is equal, but he counters that “people who have to deal with black employees find this not true”. He says that you should not discriminate on the basis of colour, because “there are many people of colour who are very talented, but don’t promote them when they haven’t succeeded at the lower level”.

    This was the objectionable comment because it is forming a stereotype based on anecdotal evidence.

    3. He writes that “there is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically.

    Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so”.

    Do you disagree with this? Recent research suggests that 7% or more of all our genes are mutant versions that replaced earlier variants through natural selection over the last tens of thousands of years. There was little gene flow between continental clusters (“races”) during that period, so there is circumstantial evidence for group differences beyond the already established ones (superficial appearance, disease resistance).

    June 2007 article from Plos Genetics, ‘Localizing Recent Adaptive Evolution in the Human Genome’, provides examples of localized evolution of cognitive function.
    provides examples of localized evolution of cognitive function.

    “Several genes with functional roles in the development and function of the nervous system show very strong evidence (CLR p < 10−5) for a recent selective sweep. For example, SV2B, a gene encoding a synaptic vesicle protein with highest expression during brain development [36], exhibits strong evidence for a selective sweep in the African-American sample. Likewise, the protein encoded by DAB1 plays a developmental role in the layering of neurons in the cerebral cortex and cerebellum [37], and exhibits strong evidence for a selective sweep in the Asian sample. Other nervous system genes with strong evidence for a selective sweep include two candidate genes for Alzheimer disease (APPBP2 and APBA2) that bind the amyloid-beta precursor protein, two genes (SKP1A and PCDH15) with a role in sensory development, and several others with various roles in nervous system development and function (PHACTR1, ALG10, PREP, GPM6A, and DGKI).” June 2007 article from Plos Genetics, Localizing Recent Adaptive Evolution in the Human Genome

    The March 2007 article from Plos Biology, A Map of Recent Positive Selection in the Human Genome:

    “Recent articles have proposed that genes involved in brain development and function may have been important targets of selection in recent human evolution [8,9]. While we do not find evidence for selection in the two genes reported in those studies (MCPH1 and ASPM), we do find signals in two other microcephaly genes, namely, CDK5RAP2 in Yoruba, and CENPJ in Europeans and East Asians [46]. Though there is not an overall enrichment for neurological genes in our gene ontology analysis, several other important brain genes also have signals of selection, including the primary inhibitory neurotransmitter GABRA4, an Alzheimer’s susceptibility gene PSEN1, and SYT1 in Yoruba; the serotonin transporter SLC6A4 in Europeans and East Asians; and the dystrophin binding gene SNTG1 in all populations.”

  11. #11 Greg Laden
    September 7, 2009

    [8]
    He’s not, but if he actually proposed a serious model along the terms of your original statement then I would certainly concede the point. Indeed. I was thinking more of “actual scientist who should know better” than “serious model”

    But it was not really a stupid offhand statement. It was the most recent in a long history of similar expressions. That he disavowed it was a testament to everyone else, not him.

    [9]“It’s an established fact. If they didn’t, they wouldn’t show up as highly separated clusters on PCA graphs.” IT does not matter how Principle Componants match to races in your brain as much as on the ground. Literally. THe null model for geographically distinct samples of muttiple non-independent random variables is separate PCA’s that get more separate as the universe of the sample gets larger. Most studies use very uneven sampling. This guarantees very distinct clusters (from random data).

    The conclusions that can be drawn about populatio movements, and the conclusions that can be drawn about male vs. female behaviors, or about expanding populations vs. bottlnecks, etc. are mostly reasonable from geographical analysis of genes, but the race-like clustering is not a valid conclusion, but either a presumption or an irrelevancy to the study.

  12. #12 Greg Laden
    September 7, 2009

    [10] Regarding point 1, saying it is “quite clear” is hardly sufficient. Watson was speaking through his ass and the testing is not clear at all. In study after study after study that looks at developmentally at risk populations to see if there are developmental differences leading to differential “IQ” scores, those differential IQ scores are found. In study after study that look for multiple different causes of these differences, including heritage, heritage comes in last (indistinguishable from random, or nil) and other factors prevail. No matter how many studies are done, racists interpreters always find a way to ignore the scientific truth and spout their crap. Funny how that works.

    ““there is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically.”

    Straw man warning. The repeated onslaughts of bullshit rarely ask this question. Rather, they simply seek to find inferiorities in intelligence among blacks which can the be used to explain social and cultural lags, inadequacies, and deprivations, real or imagined. It’s called blaming the victim.

    “There was little gene flow between continental clusters (“races”) during that period”… and you say this absurd statement with no basis in fact and huge amounts of data contradicting it … why?

    The studies you cite are interesting but mostly not related to this discussion. I assure you that you are not going to get very far with studies of several abnormalities.