Racial differences in intelligence from the author of The Bell Curve

[Shalmanese]

I stumbled across this article by Charles Murray, the coauthor of the infamous “The Bell Curve” which purports to show innate racial differences in intelligence. This article serves as an update somewhat, integrating some of the latest research into the issue.

Since I’m not nearly well versed enough to offer a balanced critique of the work, I thought I would throw it out here and see what people think. From what I’ve been able to dig up, it seems like some of the evidence Murray presents seems very compelling but I know how easy it is to seem convincing to an outsider so I’m reserving judgement at the moment.

Two issues that particularly interested me are his critique of Lewontin’s claim that “race is a social construct” and his reply to Stephen Jay Gould’s Mismeasure of man.

Turning to race, we must begin with the fraught question of whether it even exists, or whether it is instead a social construct. The Harvard geneticist Richard Lewontin originated the idea of race as a social construct in 1972, arguing that the genetic differences across races were so trivial that no scientist working exclusively with genetic data would sort people into blacks, whites, or Asians. In his words, “racial classification is now seen to be of virtually no genetic or taxonomic significance.”[25]

Lewontin’s position, which quickly became a tenet of political correctness, carried with it a potential means of being falsified. If he was correct, then a statistical analysis of genetic markers would not produce clusters corresponding to common racial labels.

In the last few years, that test has become feasible, and now we know that Lewontin was wrong.[26] Several analyses have confirmed the genetic reality of group identities going under the label of race or ethnicity.[27] In the most recent, published this year, all but five of the 3,636 subjects fell into the cluster of genetic markers corresponding to their self-identified ethnic group.[28] When a statistical procedure, blind to physical characteristics and working exclusively with genetic information, classifies 99.9 percent of the individuals in a large sample in the same way they classify themselves, it is hard to argue that race is imaginary.

Following the cites, I get this article(pdf) and this NYT article which seems to be largely confirming what he’s said. I’ve heard this claim of “race is a social construct” and “the variation within races is greater than the variation between races” and so forth. If I understand the cited articles correctly, this isn’t as big a deal as Murray makes it out to be but it does suggest further avenues to investigate the true variability between races and does mean that Lewontin’s claim is incorrect.

The second thing is Murray’s response to “The Mismeasure of Man” which is buried all the way in the notes:

[65] Factor analysis can be conducted in many different ways, which has led to widespread popular acceptance of one of Stephen Jay Gould’s allegations in his best-selling book, The Mismeasure of Man (1981), namely, that g is a statistical artifact that appears only when certain analytic choices are made. Actually, the opposite is true. A single factor, typically explaining about three times as much variance as all the other factors combined, emerges under all of the normal methods of conducting a factor analysis. The only exception occurs if the factor-analysis program is explicitly instructed to apportion the variance in such a way that a single factor does not emerge. But if you do that and then try to publish your results, the reviewers will point out that if you hadn’t issued that instruction, you would have gotten a dominant single factor. As Richard Herrnstein liked to say, “You can make g hide, but you can’t make it go away.” For a review of this issue with sources, see the Afterword to the softcover edition of The Bell Curve (559-62). For a technical demonstration of the convergent results from alternative ways of conducting a factor analysis, see Ree and Earles (1991). For a wide-ranging set of articles about the current role of g in understanding intelligence, see the articles in the special section of the January 2004 issue of Journal of Personality & Social Psychology commemorating the 100th anniversary of Spearman’s discovery of g. An overview is given in Lubinski (2004).

[66] Gould (1981) still shapes the lay received wisdom about IQ tests, but his denunciation of g was already technically outdated when it was published. For an account of the differing ways in which The Mismeasure of Man was assessed by the media and by scholars, see Davis (1983). For a recent discussion of the nature of g and the issues that Gould was wrong about, see Bartholomew (2004).

For the longest time, I understood the recieved wisdom to be that the Bell Curve was pseudoscience and The Mismeasure of Man was an adequate debunking of it, thus it was safe to ignore everything Murray had to say. Following the citation to Davis got this article which claims that while the reaction to TMoM was overwhelmingly positive in the mainstream press, the scientific community, including Science and Nature, claimed it was a shoddy work. Checking out his claim about the Nature article confirms that it was a stunning denoucement of the validity of TMoM. It’s hard to convey just how negative that review is of the book without reading the entire thing.

And here is somewhere I am on comfortable ground. While Murray can present twisted facts from shoddy journals to bolster his claim, Nature is a reputable journal and this is a piece of evidence that is hard to ignore. It appears that there is at least some legitimate evidence to the claim that TMoM was a poor peice of science. Digging further reveals that Wikipedia also has a decent summary of the criticisms of TMoM.

TMoM has been cited frequently in GD and many other places as a debunking of racial differences. If TMoM is indeed a shoddy piece of pseudoscience, then what does this have to say about the actual validity of the Bell Curve and of all the subsequent arguments that Murray makes in the above article? It’s starting to seem to me that the no-racial-differences side has been arguing in a dishonest fashion and that makes me start to doubt their claims.

But again, I acknowledge that I am not an expert in this field so it’s possible that I have the wrong impression of things. I’d appreciate other, more qualified people’s take on this.

[Shagnasty]

I will set myself up and take it from a slightly higher level. I was in an Ivy League graduate school based in the psychology department when the controversy about The Bell Curve Hit. We had to take a survey course among every area in the department anyway so the resident professor who was an intelligence expert gave us an entire course on the Bell Curve. Like many other people, we picked apart the research methodological flaws and illogical conclusions.

However, we did not stop there. We asked if the the ideas within the book (which are mainly rather well accepted already if a little discouraging) had any basis in reality. Of course they do and they are strong. Black populations of any size, at least in the U.S., always score lower on every type of “intelligence test” you give the groups whether it is IQ tests, standardized school assessment exams, exit exams, the SAT, GRE, and others. The first reaction would be that blacks as a whole get dropped down by some of their very poor brethren. In fact, you can match cohort against cohort and blacks still score lower within the groups.

People tend to assume that any difference between groups such as this must be social or at least environmental and that may be the case some day but nobody has never shown the causes of these rather strong effects very well otherwise.

I am well aware of the problems with the genetic concepts of race and have read virtually every thread here about it for years. However, I will just throw myself to the sharks and give what I see as a flaw in that whole line of thinking. The Out of Africa Hypothesis states that all of mankind was formed when a small band (maybe very small) of a certain group of Africans picked up and started populating the rest of the planet. Therefore, we are all very closely related and only have biological diversity from the past tens of thousands of years.

Sounds good? Wait a second I think. What about all of those other African groups that did not leave Africa and weren’t the most direct ancestors of the other groups. That problem is actually acknowledged when scientists claim that “Africa has more human genetic diversity that anywhere else on the planet.” That statement is usually used as a different kind of evidence but it doesn’t have to be positive and it could easily explain lots of things we see from sports performance in exceptional individuals to lower median test scores. I feel a little scammed.

The last part is almost a question from me but it seems to have merit the more I read.

***All the standard CYA PC disclaimers apply.

[monavis]

As I see it there is only one Race that is the human race,th human race is made up of people of different cultures,colors,sizes shapes,eyes eyc.

It would be a better world in my opinion if people just saw people as fellow passengers of this Space Ship called earth. all wanting love, respect,happiness and equal oppertunities.

Monavis

[ralph124c]

Most black people in the USA actually are of mixed race origin. How doe American black people compare to African black people in these comparisons?

[Gukumatz]

@monavis

As I see it there is only one Race that is the human race,th human race is made up of people of different cultures,colors,sizes shapes,eyes eyc.

It would be a better world in my opinion if people just saw people as fellow passengers of this Space Ship called earth. all wanting love, respect,happiness and equal oppertunities.

Monavis

All perfectly desirable blather, but, alas, this is currently about research. If there ever comes the time and place where someone tries to implement policy on this basis, I’ll be in lockstep with you, hippy flag a’waving. Until then . . .

[eponymous]

A few points I’ll comment on with regards to Lewontin’s claim race is a social construct:

Two issues that particularly interested me are his critique of Lewontin’s claim that “race is a social construct” and his reply to Stephen Jay Gould’s Mismeasure of man.

Quote: Turning to race, we must begin with the fraught question of whether it even exists, or whether it is instead a social construct. The Harvard geneticist Richard Lewontin originated the idea of race as a social construct in 1972, arguing that the genetic differences across races were so trivial that no scientist working exclusively with genetic data would sort people into blacks, whites, or Asians. In his words, “racial classification is now seen to be of virtually no genetic or taxonomic significance.”[25]

Lewontin’s position, which quickly became a tenet of political correctness, carried with it a potential means of being falsified. If he was correct, then a statistical analysis of genetic markers would not produce clusters corresponding to common racial labels.

Notice Murray’s slight jab at Lewontin, indicating that his position “quickly became the tenet of political correctness”. Which may have been true, for all we know, but I don’t know why he would make such a claim given he quoted Lewontin above - “racial classification is now seen to be of virtually no genetic or taxonomic significance.” Where’s the political correctness in this statement? I don’t see it.

As to this sentence - “If he was correct, then a statistical analysis of genetic markers would not produce clusters corresponding to common racial labels.”

This is NOT what Lewontin is saying, or at least, that’s my impression of Lewontin’s statement. I don’t doubt that Lewontin would agree that one could do so, but here’s the kicker - from a genetic/biological basis it would have no genetic or taxonomic significance.

In the last few years, that test has become feasible, and now we know that Lewontin was wrong.[26] Several analyses have confirmed the genetic reality of group identities going under the label of race or ethnicity.[27] In the most recent, published this year, all but five of the 3,636 subjects fell into the cluster of genetic markers corresponding to their self-identified ethnic group.[28]

Which genetic markers are we talking about? And from what category and number of races did people choose? 5? 10? 50? 100? By what criteria were the races pre-selected for individuals to choose from?

When a statistical procedure, blind to physical characteristics and working exclusively with genetic information, classifies 99.9 percent of the individuals in a large sample in the same way they classify themselves, it is hard to argue that race is imaginary.

Which is bullshit - Lewontin and others ARE NOT saying that race is imaginary - what they have said repeatledly is that race is a social construct, that THERE IS NOTHING COHERENT about the concept of race (as it is commonly understood in layman’s terms) from a biological/genetic perspective. Which leaves the question of whether race is coherent or useful from the cultural/sociological perspective unaddressed. I don’t think Lewontin and others are arguing that one CAN’T examine race from this (cultural/sociological) perspective, just that it doesn’t make much sense in examining the concept of race from a genetic/biological perspective.

TMoM has been cited frequently in GD and many other places as a debunking of racial differences. If TMoM is indeed a shoddy piece of pseudoscience, then what does this have to say about the actual validity of the Bell Curve and of all the subsequent arguments that Murray makes in the above article? It’s starting to seem to me that the no-racial-differences side has been arguing in a dishonest fashion and that makes me start to doubt their claims.

I can’t comment cogently on the criticisms of Gould’s Mismeasure of Man as I am not well versed in its arguments (although I have read it), but I do not doubt that there are some valid criticisms of the work. That being said, however, I wouldn’t rely of the Mismeasure of Man as the sole source in critiquing or debunking the claims made by Murray and Hernstein in the Bell Curve. There’s plenty of literature available that have done so, so I hardly think that any criticism of The Mismeasure of Man somehow validates the claims made by the Bell Curve. At best, I suppose one can claim it as “counter-propaganda” in that rather than critiquing the Bell Curve directly, it indirectly critiques it using a different philosophical or political perspective. Which, I suppose, may be a valid criticism by Murray, but others can (and have) made similar claims to Murray’s (and others) work as well.

[Shagnasty]

@eponymous

A few points I’ll comment on with regards to Lewontin’s claim race is a social construct:

Notice Murray’s slight jab at Lewontin, indicating that his position “quickly became the tenet of political correctness”. Which may have been true, for all we know, but I don’t know why he would make such a claim given he quoted Lewontin above - “racial classification is now seen to be of virtually no genetic or taxonomic significance.” Where’s the political correctness in this statement? I don’t see it.

As to this sentence - “If he was correct, then a statistical analysis of genetic markers would not produce clusters corresponding to common racial labels.”

This is NOT what Lewontin is saying, or at least, that’s my impression of Lewontin’s statement. I don’t doubt that Lewontin would agree that one could do so, but here’s the kicker - from a genetic/biological basis it would have no genetic or taxonomic significance.

Which genetic markers are we talking about? And from what category and number of races did people choose? 5? 10? 50? 100? By what criteria were the races pre-selected for individuals to choose from?

Which is bullshit - Lewontin and others ARE NOT saying that race is imaginary - what they have said repeatledly is that race is a social construct, that THERE IS NOTHING COHERENT about the concept of race (as it is commonly understood in layman’s terms) from a biological/genetic perspective. Which leaves the question of whether race is coherent or useful from the cultural/sociological perspective unaddressed. I don’t think Lewontin and others are arguing that one CAN’T examine race from this (cultural/sociological) perspective, just that it doesn’t make much sense in examining the concept of race from a genetic/biological perspective.

I can’t comment cogently on the criticisms of Gould’s Mismeasure of Man as I am not well versed in its arguments (although I have read it), but I do not doubt that there are some valid criticisms of the work. That being said, however, I wouldn’t rely of the Mismeasure of Man as the sole source in critiquing or debunking the claims made by Murray and Hernstein in the Bell Curve. There’s plenty of literature available that have done so, so I hardly think that any criticism of The Mismeasure of Man somehow validates the claims made by the Bell Curve. At best, I suppose one can claim it as “counter-propaganda” in that rather than critiquing the Bell Curve directly, it indirectly critiques it using a different philosophical or political perspective. Which, I suppose, may be a valid criticism by Murray, but others can (and have) made similar claims to Murray’s (and others) work as well.

I agree with you for the most part but I do believe that many people dive down into the specifics right away just to evade what many people think intuitively think is the obvious. I know for a fact that Africa has many different “black” groups that aren’t much related in any way so that we can make a blanket statement about any of them.

I will just throw one controversial statement out here that I am not tied to but I understand is possible. What if the small group of Africans that left Africa and populated the world had some characteristics that most that are left there do not have. Those could include many things including the abilities that were later included by those same groups much later to define IQ and much of our society.

The blacks that exist in America weren’t randomly sampled from blacks around the world. They are kidnapped from smaller groups in West Africa and populated what is now the U.S. as well. Isn’t it completely possible that there were traits and lack of traits that were retained from groups that were never part of the initial migrations?

I have little specific opinion on this matter at all except from the scientific viewpoint. I think that many opinionated people have tried to prove that all groups are exactly equal in all ways and I can think of many valid reasons why this may not be true. I understand perfectly why all people of black skin cannot be lumped together in any coherent way but that does not invalidate any hypothesis that any person brings forth suggesting a difference between two different populations.

[Lissa]

@Shagnasty

People tend to assume that any difference between groups such as this must be social or at least environmental and that may be the case some day but nobody has never shown the causes of these rather strong effects very well otherwise.

That wouuld be my first reaction-- to point to social causes: that black Americans tend to be poor and thus are affacted from childhood by poor nutrition, educational/socialization disadvantages and other environmental factors which would have an impact on adult intelligence.

What other causes could there really be? I’ve never heard any suggestion that the brains of African-Americans have less synapses or any other physical difference which would hinder intelligence.

[BrainGlutton]

I recall reading in The Bell Curve Wars – or perhaps it was another book called The Bell Curve Controversy, which I got from the library a few years ago but now can’t find on Amazon – that many Third-World countries have shown a one standard-deviation increase in measured average IQ since WWII, and without any significant change in their gene pools; the improvement can only be attributed to improved nutrition, education, sanitation and health care. Furthermore, a study of children fathered during WWII by black American soldiers on German women, and raised in Germany as Germans, shows no significant difference between their IQs and the general population’s.

So if black Americans have a measured IQ bell curve significantly to the left of white Americans’ bell curve – and they do, that part is not even controversial – I think the likeliest explanation for that is not that they are mentally inferior by heredity, but that growing up black in America is like growing up an average citizen in an underdeveloped country – you just don’t get the opportunity to fully develop your mind’s potential.

[tomndebb]

@Shalmanese

For the longest time, I understood the recieved wisdom to be that the Bell Curve was pseudoscience and The Mismeasure of Man was an adequate debunking of it, thus it was safe to ignore everything Murray had to say.

Certainly, the popularity of Gould has provided The Mismeasure of Man a podium from which to attack The Bell Curve and, unfortunately, many people will rely on Gould in the way that others rely on Murray, but that was simply the battle for popular opinion. Gould does not effectively take apart The bell Curve, making several errors of his own. The Bell Curve (deliberately published without peer review to get its propaganda out to the public without hindrance) was assaulted by counter propaganda (including that from Gould), initially. However, later actual methodological review has demonstrated that The Bell Curve’s second half was seriously flawed; we should simply look to better reviews than that of Gould to see them.

---

From the NYT link:

But if many—a few hundred—variable genes are considered simultaneously, then it is very easy to do so. Indeed, a 2002 study by scientists at the University of Southern California and Stanford showed that if a sample of people from around the world are sorted by computer into five groups on the basis of genetic similarity, the groups that emerge are native to Europe, East Asia, Africa, America and Australasia—more or less the major races of traditional anthropology.

This refers to the Science article “Genetic Structure of Human Populations” Noah A. Rosenberg, Jonathan K. Pritchard, James L. Weber, Howard M. Cann, Kenneth K. Kidd, Lev A. Zhivotovsky, and Marcus W. Feldman, Science 20 December 2002: 2381-2385.
(And note the “more or less” disclaimer.)

However, the NYT article omits an important aspect of the study. Rosenberg, et al. did find that clusters of loci could identify general geographic points of origin. However, using greater or fewer clusters changed the shape of the geographic distribution. The more clusters that were used, the closer they could get to identifying the actual local region from wich a person came. In other words, relying on six(?) clusters, they could point to Africa or Eastern Asia or the Americas, but using eight they could sometimes take it down to a particular area between two rivers or mountains. The break-off at the continental level, while interesting, did not actually define a group; it simply showed their general place of origin.

As an analogy: if we have three people whose grandparents are named (1) Murphy, O’Brien, Doyle, and Cooley, (2) O’Reilly, Kelly, Corrigan, and McNulty, and (3) Szewcyk, Przbilski, Kowalski, and Michalek, we can prabably determine that persons 1 and 2 have Irish ancestry and person 3 has Polish ancestry. Note, however, that we do not have any information that persons 1 and 2 are actually related beyond having a similar geographic origin. This is why Cavalli-Sforza and others have moved away from the use of “race” and toward the use of the word “population” in their analyses, even though Cavalli-Sforza had “racial” analysis earlier in his career. We can find populations of people who are actually related, but the racial categories are so broad as to be meaningless.

---

I will also basically agree with Shagnasty’s overall points in his second post.

[elucidator]

We should consider the upside. When two superior races like the Scotch-Irish and Cherokee are mingled, the resultant hybrid is markedly superior in every respect, which has led to the dominance of Texans in the social, political and intellectual spheres. Those of us so blessed should make ourselves freely available as providers of superior genetic material. As stern duty demands.

[eponymous]

@Shagnasty

I will just throw one controversial statement out here that I am not tied to but I understand is possible. What if the small group of Africans that left Africa and populated the world had some characteristics that most that are left there do not have. Those could include many things including the abilities that were later included by those same groups much later to define IQ and much of our society.

I don’t think this is necessarily a controversial statement. The problem is - what trait are we looking for, and how is this trait expressed genetically? There hasn’t been enough conclusive research to show just what genes are specifically related to intelligence and how those genes are expressed within a given population that allow one to infer the linkage.

The blacks that exist in America weren’t randomly sampled from blacks around the world. They are kidnapped from smaller groups in West Africa and populated what is now the U.S. as well. Isn’t it completely possible that there were traits and lack of traits that were retained from groups that were never part of the initial migrations?

Not entirely random, but from such a large geographic area that it should be possible to identify differences in the genetic makeup of the African American population in the US. I remeber a television show that traced the lineage of several famous African Americans and scientists were able to pinpoint with a relative high degree of accuracy the area from wher there ancestors cam from (Oprah Winfrey’s ancestors were from around Liberia; Chris Tucker’s ancestors were from Angola; the host of the program - an African American - has a genetic make-up that was more common with various European populations!!).

I have little specific opinion on this matter at all except from the scientific viewpoint. I think that many opinionated people have tried to prove that all groups are exactly equal in all ways and I can think of many valid reasons why this may not be true. I understand perfectly why all people of black skin cannot be lumped together in any coherent way but that does not invalidate any hypothesis that any person brings forth suggesting a difference between two different populations.

I don’t think there is any questions that there are differences with respect to populations. It’s just how one defines the populations (on what basis can we make a valid claim to place person X in a particular category?) According to geneticists, we should look at genetic makeup, rather than how that genetic makeup is expressed morphologically (outward appearance).

[John_Mace]

@Shagnasty

I will just throw one controversial statement out here that I am not tied to but I understand is possible. What if the small group of Africans that left Africa and populated the world had some characteristics that most that are left there do not have. Those could include many things including the abilities that were later included by those same groups much later to define IQ and much of our society.

That’s certainly possible, but until we actually identify genes asscoiated with “intelligence”, it’s going to remain speculation. I just want to empahsize that, and I realize you’re not asserting that it’s anything more.

There are a number of problems with the whole race vs intelligence thing, not the least of which is that we know there are many environmental factors that affect intelligence. We clearly don’t, for example, know what all the factors are so we can’t simply control for them. One recent study (don’t have a cite, but it was in the NYT Sunday magazine article about educational techniques a week or so ago), showed how children’s IQs correlate with the total number of (different) words that they hear at home when they are of pre-school age. The list goes on and on.

But if we wanted to study the heritability of intelligence, scientists wouldn’t start with race as the variable against which to measure it, because race is a poor substitute for relatedness (as **tomndebb **already pointed out). And we certainly wouldn’t use “Black”, in the American sense, since that isn’t even accurate from an ethnicity standpoint (American Blacks being of widely mixed ancestry). Of all the races that are social constructs, American Blacks have to be at the top of the list due to extensive interbreeding with other races. On average, American Blacks are only about 75-80% African by ethnicity, and the standard deviation for that quantity is quite high.

There is some research focused on understanding what behavioral evolution human groups might have undergone since our dispersal out of Africa, and you can read quite a bit about that in the recently published book Before the Dawn by Nicholas Wade . Of course, you have to take much of this research with a grain of salt since one or two academic papers on a given subject do not a scientific concensus make. This is all cutting age stuff and there’s no telling how much of it will stand up to closer scrutiny.

Who knows-- maybe at some future point we will be able to accurately measure “intelligence”, or certain aspect of “intelligence”, and be able to relate that to certain gentic traits found in varying frequency among different ethnic groups. Iintellgence has to have some heritable component, othewise we’d be no smarter than chimps. But we’re a long way from knowing those details, and I wouldn’t put much stock in anyone’s claim that we do know much about it.

And even if we could say that group A and group B have a mean “intelligence” factor that differs by X amount, that still wouldn’t tell us anything about the intelligence of any given individual in those two groups. For example, if we wanted to develop educational methods for different intelligence levels, we’d still have to measure everyone in both groups individually, and not just assign members to intelligence categories based on their membership in the two groups.

[Valteron]

I am sometimes called upon to recommend people for hiring or to hire people for specific contracts. Now as a rule, I hire one or two persons at a time, so I judge them on their interview performance, their skills, or certain tests I administer.

Now as I understand, none of these scientific examinations of race and IQ have ever infered that any given member of one race is necessarily smarter than any given member of another race. So the average IQs of one race compared to another would not be of much use to me in identifying good potential employees.

But if ever the day comes that I am called upon to fill a couple of billion jobs and that I decide to fill them with every member of the white race or the black race or the yellow race, or what have you, I would find these scientific studies of enormous value in making my decision. :rolleyes: :rolleyes: :rolleyes:

[John_Mace]

@eponymous

Not entirely random, but from such a large geographic area that it should be possible to identify differences in the genetic makeup of the African American population in the US. I remeber a television show that traced the lineage of several famous African Americans and scientists were able to pinpoint with a relative high degree of accuracy the area from wher there ancestors cam from (Oprah Winfrey’s ancestors were from around Liberia; Chris Tucker’s ancestors were from Angola; the host of the program - an African American - has a genetic make-up that was more common with various European populations!!).

That is a common misconception. What they were able to do was to trace the maternal and paternal lines of various people back to their likely geographic region of origin. But those would only be 2 ancestors (one famale, one male) out of the many ancestors that person would have had from 200 -300 years ago.

The host of that show, Louis Gates Jr., was found to have had paternal and maternal lines that originated in Europe, but he was still determined to have had about 50% of his ancestory from Africa. It was just really hard to pinpoint where in Africa that genetic component came from. It would be no different than telling a White person with the last name of O’Neill that he was Irish, even if his family had been in the US since long before the Civil War and he had no idea whether he has that last name because of one Irish ancestor from 150 years ago, or whether all of his ancestors hailed from Ireland. Assuming 25 years per generation, that person could be as little as 1/64 Irish.

[pantom]

Sigh.
Note :

Ambrose concludes that bottlenecks occurred among genetically isolated human populations because of a six-year long volcanic winter and subsequent hyper-cold millennium after the cataclysmic super-eruption of Toba. This volcanic winter played a role in recent human differentiation. The resultant combination of founder effects and genetic drift may account for *low human genetic diversity as well as population differences associated with so-called races. The bottleneck hypothesis offers an explanation for why humans exhibit so little genetic variation, yet superficially appear diverse. *

I quote the above not to debate anything about the bottleneck, but to point out that the fact that humans show relatively low genetic diversity is well-known, and something that scientists are looking to explain.

Additionally,note :

Perhaps the strongest evidence against a genetic basis for intergroup differences in IQ is that the average level of mental test performance has changed very significantly for whole populations over time and, moreover, particular ethnic groups within the population have changed their relative positions during a period when there was very little intermarriage to change the genetic makeup of these groups.
While The Bell Curve cites the work of James R. Flynn, who found substantial increases in mental test performances from one generation to the next in a number of countries around the world, the authors seem not to acknowledge the devastating implications of that finding for the genetic theory of intergroup differences. . . .
The national averages have in fact changed by amounts that* are comparable to the fifteen or so IQ points separating blacks and whites in America. *To put it another way, on the average, whites today differ from whites, say, two generations ago as much as whites today differ from blacks today. Given their size and speed, the shifts in time necessarily have been due more to changes in the environment than to changes in the genes.
. . . *When any factor differs as much from Al to A2 as it does from A2 to B2, why should one conclude that this factor is due to the difference between A in general and B in general? *That possibility is not precluded by the evidence, but neither does the evidence point in that direction.(2.)

In short, in order to find that IQ differences are due to race, given the limited genetic variability of humans in general, and not culture or the general advance of group A and B together, where group A maintains an economic and social advantage over group B, you’d have to be predisposed to thinking that group A is inherently superior to group B.
Also, if you’ve ever taken an intro to Linguistics course, and figured out what it takes in terms of mental gymnastics to construct even a simple sentence, something that any normal human being can do without effort, you’d never again take this kind of simple-minded stuff about how people do on an IQ test seriously again.
It should also be pointed out that if Africa has the greatest genetic diversity, then the chances that it’s going to be deficient in whatever gene or genes controls relative intelligence levels, assuming there is one, would be lower for African than it would for non-African populations, just as a matter of logic.

[threemae]

@eponymous

This is NOT what Lewontin is saying, or at least, that’s my impression of Lewontin’s statement. I don’t doubt that Lewontin would agree that one could do so, but here’s the kicker - from a genetic/biological basis it would have no genetic or taxonomic significance.

Which genetic markers are we talking about? And from what category and number of races did people choose? 5? 10? 50? 100? By what criteria were the races pre-selected for individuals to choose from?

Well, read the methods in this paper then:
http://scholar.google.com/scholar?hl=en&lr=&safe=off&cluster=11206474945038194575

"Material and Methods
Subjects
The FBPP is a collaborative effort of four research networks
(GenNet, GENOA, HyperGEN, and SAPPHIRe)
that aims to investigate high blood pressure and related
conditions in multiple racial/ethnic groups (FBPP Investigators
2002). Each network has been funded by the
National Heart, Lung, and Blood Institute (NHLBI) since
1995. In total, DNA samples from 10,527 participants
were genotyped at 326 autosomal genome screen microsatellite
markers by the NHLBI-sponsored Mammalian
Genotyping Service (Marshfield, WI) (screening set 8)
and had sufficient marker data for analysis (i.e., at most
40 missing genotypes).
Race/ethnicity information was obtained by self-description.
HyperGEN focused their recruitment on whites
and African Americans…
Because of its focus on linkage analysis of hypertension,
the FBPP recruited sibships or nuclear families that
typically had at least one hypertensive index subject, although
precise ascertainment criteria varied among networks
(FBPP Investigators 2002). For analyses focusing
on genetic stratification bias with respect to blood pressure,
we selected the hypertensive individual (“case”)
from those families with a single hypertensive subject
and no other relatives and a single, randomly selected
hypertensive individual from families with multiple hy…
pertensive subjects and at most one normotensive subject.
To obtain “controls,” we selected the normotensive
subject from those families with a single normotensive
subject and no relatives and a single, randomly selected
normotensive individual from families with multiple
normotensive subjects and at most one hypertensive individual.
For the networks and field centers that included
only hypertensive subjects, this analysis was not possible.
If a family contained exactly one hypertensive subject
and one normotensive subject or more than one
hypertensive subject and more than one normotensive
subject, the family was not included in this analysis.
Genetic Distance Analysis
We created 18 subpopulations on the basis of the
participants’ SIRE and the recruitment site (the few individuals
who identified their race/ethnicity as “other”
were excluded from this analysis). As a measure of genetic
distance, we computed the “coancestry coefficient”
among groups (Reynolds et al. 1983). The coancestry
coefficient is a measure of distance that is closely related
to an average value of FST across genes. To visualize these
genetic distances, we performed multidimensional scaling
(MDS) analysis (Mardia et al. 1980). In simple terms,
this analysis provides a configuration of 18 points on a
two-dimensional plane, such that the Euclidean distances
among these points match the genetic distance matrix
as closely as possible.
…
"

So, basically looking at microsatellite markers, or some of the “junk” DNA from non-encoding portions of the genome. I suppose that’s a valid critique of the work: it doesn’t address DNA that leads to phenotypic differences, it just deals with the “junk” DNA that changes at relatively consistent rates over time. I’m sure you could do a similar analysis with mitochondrial DNA and get similar results, but I’m not sure that differences in mitochondrial DNA would tell you something interesting about meaningful racial differences, just that indeed there is some genetic basis for race.

http://www.bio.davidson.edu/COURSES/genomics/method/microsatellite.html

[athelas]

@threemae

I’m sure you could do a similar analysis with mitochondrial DNA and get similar results, but I’m not sure that differences in mitochondrial DNA would tell you something interesting about meaningful racial differences, just that indeed there is some genetic basis for race.

Yep, in mol bio lab, we sequenced a fragment of mDNA from each student, then plotted them on a tree. There were few or no black students, but the greatest (highest-level) split was between Asian and Caucasian students. Definitely shows that there is a clear genetic difference.

As for racial differences, the fact that there are visible phenotypic differences, as well as different incidences of different genetic diseases should demonstrate that group variation is not confined to noncoding regions.

[tomndebb]

@athelas

There were few or no black students, but the greatest (highest-level) split was between Asian and Caucasian students. Definitely shows that there is a clear genetic difference.

As for racial differences, the fact that there are visible phenotypic differences, as well as different incidences of different genetic diseases should demonstrate that group variation is not confined to noncoding regions.

Who was classified as “Caucasian” or Asian? How many “Caucasians” were Ukrainian or Georgian who might have had Mongol ancestors? Were the Afghanis, Iranis, Nepalese, Indians, and Saudis considered “Caucasian” or Asian?

In other words, did the tests demonstrate that there were “races” or that people from distant lands (Western Europe and Eastern Asia) were more distinct while not actually addressing the aspect of groups who were geographically proximate?

[The_Flying_Dutchman]

@pantom

It should also be pointed out that if Africa has the greatest genetic diversity, then the chances that it’s going to be deficient in whatever gene or genes controls relative intelligence levels, assuming there is one, would be lower for African than it would for non-African populations, just as a matter of logic.

That would be logical if we assume our genome is fixed.

The last time I looked into this topic about a year ago, the breaking news was the discovery of a brain gene variant of microcephalin that appeared in the human population 37,000 ago outside of Africa. Googling now, there appears to be a lot of scientific speculation that 70% of us inherited this variant from neanderthals who did not inhabit Africa.