# Can the Black-White racial IQ gap in the US be environmentally explained? **URL:** \ **Category:** Great Debates\ **Created:** [July 1, 2012, 4:56am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877 "2012-07-01T04:56:56Z")\ **Posts on this page:** 20\ **Page:** 10
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 10, 2012, 5:31pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/181 "2012-07-10T17:31:13Z")
That Scarr finding (and btw, it was a long time ago, has anyone every repeated it? I think any epidemiological study is suspect until it’s been examined by a number of disinterested parties) … doesn’t negate the possibility that there could be an “on/off” genetic cluster that anyone with \>x% West African ancestry has. ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [July 10, 2012, 5:32pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/182 "2012-07-10T17:32:28Z")
> [@NojNoj](#): > > That Scarr finding (and btw, it was a long time ago, has anyone every repeated it? I think any epidemiological study is suspect until it’s been examined by a number of disinterested parties) … doesn’t negate the possibility that there could be an “on/off” genetic cluster that anyone with \>x% West African ancestry has. Yes it does. Think about it. ---
**Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 10, 2012, 5:35pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/183 "2012-07-10T17:35:33Z")
> [@Evil\_Economist](#): > > Yes it does. Think about it. Not if everyone in the sample was \>x (And here’s reference on why one should be dubious about these sorts of statistical studies: [http://www.nytimes.com/2012/04/17/science/rise-in-scientific-journal-retractions-prompts-calls-for-reform.html?pagewanted=all](http://www.nytimes.com/2012/04/17/science/rise-in-scientific-journal-retractions-prompts-calls-for-reform.html?pagewanted=all) Another skeptic took a large data set and just by carefully choosing a subset he was able to “prove” that listening to the beatles lowered a subject’s biological age by 1.5 years. ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [July 10, 2012, 5:45pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/184 "2012-07-10T17:45:34Z")
> [@NojNoj](#): > > Not if everyone in the sample was \>x > > (And here’s reference on why one should be dubious about these sorts of statistical studies: [http://www.nytimes.com/2012/04/17/science/rise-in-scientific-journal-retractions-prompts-calls-for-reform.html?pagewanted=all](http://www.nytimes.com/2012/04/17/science/rise-in-scientific-journal-retractions-prompts-calls-for-reform.html?pagewanted=all) > > Another skeptic took a large data set and just by carefully choosing a subset he was able to “prove” that listening to the beatles lowered a subject’s biological age by 1.5 years. Which of these is more likely: a) There is a magic gene that only appears in black people with \>x% West African ancestry, that only has the impact of lowering IQ, and no one in the data set has \ **Author:** ![NojNoj](https://avatars.discourse-cdn.com/v4/letter/n/2bfe46/32.png) [@NojNoj](https://boards.straightdope.com/u/NojNoj)\ **Post date:** [July 10, 2012, 7:50pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/185 "2012-07-10T19:50:53Z") I choose b) in this case… ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 11, 2012, 6:29am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/186 "2012-07-11T06:29:29Z")
> [@Evil\_Economist](#): > > I haven’t found a link to the original paper yet, but here’s what I have: [http://www.eurekalert.org/pub\_releases/2009-12/uop-gsc121809.php](http://www.eurekalert.org/pub_releases/2009-12/uop-gsc121809.php) :rolleyes: Way to miss the point. ---
**Author:** ![Weirdering](https://avatars.discourse-cdn.com/v4/letter/w/4af34b/32.png) [@Weirdering](https://boards.straightdope.com/u/Weirdering)\ **Post date:** [July 11, 2012, 7:44am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/187 "2012-07-11T07:44:01Z")
> [@Evil\_Economist](#): > > Never mind, my error; I linked to the wrong study. I should have linked to Scarr, Pakstis, Katz and Barker. I can’t find an online link, but see: [http://books.google.com/books?id=UW9cjBo\_nCIC&pg=PA147#v=onepage&q&f=false:](http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA147#v=onepage&q&f=false:) This was 1977. Do you know how reliable their method of estimating ancestry was? ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [July 11, 2012, 12:44pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/188 "2012-07-11T12:44:06Z")
> [@MrDibble](#): > > :rolleyes: Way to miss the point. Uh…OK, I guess I see your point: a link to a study about the genetic ancestry of African Americans is certainly missing the point of a question about the genetic ancestry of African Americans. > [@](#): > > The similarity of the West African component of African-American ancestry to the profile from non-Bantu Niger-Kordofanian speaking populations, which include the Igbo and Yoruba from Nigeria and the Brong from Ghana > > A comparison of the West African segments of African-American genomes. This is wholly in line with historical documents showing that the Igbo and Yoruba are two of the 10 most frequent ethnicities in slave trade records; however, most African-Americans also have ancestry from Bantu-speaking populations in western Africa. > > … > > We were also able to show that there is little genetic differentiation among African-Americans in the African portion of their ancestry, reflecting the fact that most African-Americans have ancestry from several regions of western Africa. The greatest variation among African-Americans is in their proportion of European ancestry, which has important implications for the design of personalized medical treatments." > > The study focused primarily on the genetic structure of West African populations, as previous genetic and historical studies suggested that the region was the source for most of the ancestry of present-day African-Americans. The results suggest that there are clear and discernible genetic differences among some of the West African populations, whereas others appear to be nearly indistinguishable, even when comparing more than 300,000 genetic markers. The researchers note that a larger sample size would likely reveal further substructure and diversity between these populations. ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [July 11, 2012, 12:45pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/189 "2012-07-11T12:45:26Z")
> [@Weirdering](#): > > This was 1977. Do you know how reliable their method of estimating ancestry was? Feel free to link to a more recent study. ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [July 11, 2012, 12:52pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/190 "2012-07-11T12:52:00Z")
Edited to remove nasty comment ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 11, 2012, 12:52pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/191 "2012-07-11T12:52:31Z")
> [@Evil\_Economist](#): > > Uh…OK, I guess I see your point: a link to a study about the genetic ancestry of African Americans is certainly missing the point of a question about the genetic ancestry of African Americans. My point was that the [Mbuti](https://www.google.com/search?q=mbuti&hl=en&safe=off&client=ubuntu&hs=gax&channel=fs&gl=za&prmd=imvnsb&tbm=isch&tbo=u&source=univ&sa=X&ei=nXb9T5PoE4ixhAfExtDkBg&ved=0CFkQsAQ&biw=1360&bih=569) are a West African population that in no way would be world class sprinters. So speaking about “West Africans” is an imprecise non-starter. It doesn’t map to ethnicity or genetic populations in any way, shape or form. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 11, 2012, 12:53pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/192 "2012-07-11T12:53:49Z")
> [@Evil\_Economist](#): > > By the way, before deciding to use that rolleyes emoticon again, you should educate yourself; it took me about 5 seconds of visiting the Wkiki page you linked to to see that it was discussing people who live in central Africa. Let me repeat that: \*\*central \*\*Africa. So, the following question: > > Has the dual answers: 1) No, and 2) learn geography. Congo is West Africa when you talk about African Americans…(at least, that’s how it’s populations are talked about when talking about US slave provenance) But you’re right. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 11, 2012, 1:12pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/193 "2012-07-11T13:12:39Z")
damnit, I know the difference between its and it’s… ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [July 11, 2012, 6:18pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/194 "2012-07-11T18:18:16Z")
> [@MrDibble](#): > > damnit, I know the difference between its and it’s… I’d blame it on the African genes. 😉 ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 12:20am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/195 "2012-07-13T00:20:50Z")
> [@Belowjob2.0](#): > > No. Mixing two populations may result in the expression of traits that are intermediate between the two groups, or the expression of traits that are stronger or weaker than in either parent group. Mixing, in effect, creates a new population which may differ significantly from either parent group. You’ve got to be kidding me. The genetic component of the trait which we are talking about is mostly additive. As such, the performance of hybrids, _in this trait_, will be intermediate to the parental populations. The formula and a more detailed discussion of this is given [here](http://www.ncbi.nlm.nih.gov/pubmed/15641922). > [@](#): > > Where you get into trouble here is that you take politically defined categories, like black and white, which have varied over time here in the US, and try to map them on to genetic differences in population. Unfortunately, the genetic differences have no meaning without the a priori political definitions - in fact the genetic differences would not exist without the political definitions. Without extensive social engineering, black Americans would have disappeared as a distinct minority group generations ago, the way that the descendants of African slaves disappeared in Mexico and in Argentina. The comment above makes no sense. None. The hereditarian claim is that the mean difference in IQ between the US subpopulation called “Blacks” and that called “Whites” is substantially genetically conditioned just as is the difference between the subpopulation called “upper class” and that called “lower class.” It’s obviously recognized that US “Blacks” represents a genetically admixed population (with approximately 75%, 20%, and 5% West African (Negroid), European (Caucasoid), Amerindian (Amerindian) admixture respectively; after all it’s argued that this issue could (and should) readily be resolved through admixture mapping. Are saying that there can’t be genetic difference between socially defined categories? Is the mean Black-White difference in skin color and craniofacial morphology completely environmentally conditioned? Are there no mean genetic IQ differences between White “Ivy league graduates” and “High school dropouts,” despite the high White heritability of IQ. How does any of that make sense. As for the disappearance of genetic differences, I’m glad that we finally agree that some exist. I would argue that the genetic differences wouldn’t disappear completely, they would just show up under the guise of “colorism” as they due throughout Latin America. > [@](#): > > It’s understandable that you don’t want the US thesis to collapse the way the others have, but I’m afraid this one’s doomed too. Basically, there is no test score gap between self-identified blacks with majority European ancestry, and self-identified blacks of majority African ancestry. As I pointed out, there is a 0.5 SD gap between the darkest Blacks and the lightest Blacks and the correlation between IQ and color in the Black population is 0.15. If you don’t believe me, refer to [this paper](http://home.uchicago.edu/~dannyk/articles/Kreisman_Rangel_2011.pdf) which I helped along. (The authors wrote it in reply to some of my commentary on the subject.) Now it is a fact that color correlates with ancestry in the Black population; the correlation is [0.44](http://www.nature.com/ng/journal/v36/n11s/full/ng1440.html). So IQ will also correlated with ancestry. Of course, we know this since children of one White and one Black parent perform intermediate to those of two White or two Black parents. Given these facts, how could indexes of intelligence not correlate with ancestry? In counter to this evidence you point to studies which, if you look at the results correctly, are consistent with a genetic hypothesis. If you wish to discuss the specifics we can and I will explain in detail how and why they support or do not contradict a genetic hypothesis. (Basically, the authors you cited failed to take into account range restriction.) ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 12:46am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/196 "2012-07-13T00:46:49Z")
> [@Evil\_Economist](#): > > I also see the following (quote marks, but it’s a paraphrase): “mixed race children who lived with a white mother scored 11 points higher than mixed-race children who lived with a black mother. The black-white IQ gap at the time was 15 points” > > And I notice from the footnote that the mixed-race children who grew up with a white mother (and liven in a 2-parent household) had an average IQ of 104.7. > > That study right there seems to absolutely and completely destroy the “genetic” argument. I tracked down that study under reference. It was: Willerman et al. (1974) [Intellectual development of children from interracial matings: Performance in infancy and at 4 years](http://psycnet.apa.org/psycinfo/1974-25006-001). I copied the table from the study [here](http://lesacreduprintemps19.files.wordpress.com/2011/07/screen-shot-2011-07-23-at-2-03-24-pm.png?w=400&h=200) and [here](http://lesacreduprintemps19.files.wordpress.com/2011/07/screen-shot-2011-07-23-at-8-51-18-pm.png?w=393&h=272). The kids with Black mothers did perform below those with White mother, but the kids with White mothers and Black fathers still performed below those with White mother and White fathers. The difference between the biracial kids with White mothers and the White kids was 3 points, which is equivalent to a 6 point between race difference. Which is what you find at around age 4. Again the heritability of IQ is low at age four. So it’s not surprising that there is a large amount of environmental influences at these ages. More informative is the performance of adults or young adults. In the nationally representative NLSY97, there was no difference between biracial kids with White mothers and Fathers and the performance was dead in between that of Whites and Blacks. Whatever the case, the proper procedure when dealing with small Ns is to conduct a meta-analysis. If you want I could link you to all the studies done which have been peer reviewed. You will see that my point holds. The above is a typical example of how contemporary environmentalists work. Cherry picking and spin. ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 12:55am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/197 "2012-07-13T00:55:37Z")
> [@Evil\_Economist](#): > > I’m going through this thread to understand the arguments, and to argue the facts rather than just going to the pit and calling people racist d\*\*\*\*\*\*\*\*s, so please forgive the multiple posts. > > Chuck11 has blog discussing the race/performance gap. A substantial part of the blog is devoted to a discussion of the book “Understanding Human History” I quoted one passage from the book. And I did so because the author was the first to present the point in quantitative form. That said, I don’t necessarily disagree with the NPI’s positions. ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 1:26am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/198 "2012-07-13T01:26:41Z")
> [@Ibn\_Warraq](#): > > Your reasoning is absurd. ] I don’t know if you misunderstand what I’m saying or what. But I will explain this one more time. In zoological terms, nearly all African Americans (or “Blacks”) are racial hybrids. Agreed. They primarily have Negroid and Caucasoid admixture. In social terms, mixed race is used to describe individuals with parents of different socially defined races (e.g., “White” and “Black”). My whole discussion concerns socially defined races, not zoologically defined race. Again, a mixed race person is a person who has one socially defined Black parent and one socially defined White parent. Since on average the European admixture in the Black population is 20%, these individuals have 60% European admixture. Correct? That this, on average, they have more European ancestry than children of two “Black” parents (20%) and less than children of two “White” parents (98%). But, of course, there is a good deal of variance in the Black population. Some “Blacks” have 50% admixture and some have 5% admixture. So some mixed race kids, as socially defined, will have 47.5 % African admixture and some will have 75% (as my nephews). This results in a bias \*against \*a genetic hypothesis, which predicts intermediate performance due to intermediate admixture. Some of the studies might sample very European biracial kids (again socially defined) and some might sample more African biracial kids. The point here is that the variance in admixture works against a genetic hypothesis and so results in support are all that more robust. ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 1:35am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/199 "2012-07-13T01:35:51Z")
> [@Ibn\_Warraq](#): > > Agreed. Race is a myth and while “black” and “white” may be useful cultural terms they’re not scientific and they’re not terribly meaningful biologically. This is a non sequitur. You are arguing that all Black are mixed race on account of being zoological hybrids (i.e., both Negroid and Caucasoid) and then using this point to argue that there are no zoological or otherwise biologically defined races. If there are no biological races, then there are only social races (with genetic differences). If there are only social races, then Black are only a mixed race if they are socially considered to be so. But most people don’t refer to Blacks (at least those who have 2 Black parents) as being so, so your point is refuted. Your point only stands if you grant that there are relatively “pure” biological races for Blacks to be a mix of. ---
**Author:** ![Chuck11](https://avatars.discourse-cdn.com/v4/letter/c/96bed5/32.png) [@Chuck11](https://boards.straightdope.com/u/Chuck11)\ **Post date:** [July 13, 2012, 1:44am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/200 "2012-07-13T01:44:52Z")
> [@Belowjob2.0](#): > > False analogy. All modern humans belong to the same subspecies. We’re all one race, in biological terms. Zoological race is a subtype of biological race; the terms are not equivalent. Two other biological race concepts are “breeding populations” and “ecotypes.” Unquestionably, there are human biological races of the latter two types. As such, your conclusion can not stand. [Previous page](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877.md?page=9) [Next page](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877.md?page=11)