# 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:** 11
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [July 13, 2012, 1:51am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/201 "2012-07-13T01:51:44Z")
> [@Chuck11](#): > > Unquestionably, there are human biological races of the latter two types. As such, your conclusion can not stand. Unquestionably, there are not, so you claim is refuted. ---
**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, 2:00am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/202 "2012-07-13T02:00:07Z")
> [@Evil\_Economist](#): > > Doing a bit of research, I find the following from the Minnesota Transracial Adoption Study’s author (discussing The Bell Curve): > > Let’s take a look at the money portion of that quote again: > > Whoops, that sounds like another nail in the coffin for the “genetic” team. I discussed this study: > [@](#): > > Scarr et al. (1977) tested the genetic hypothesis in two ways. First, they looked to see if g was associated with an index of African ancestry and found a statistically non-significant -.05 correlation and, second, they divided their subjects into thirds based on their index of ancestry and compared the g scores of the top third to the bottom third; the latter analysis showed a non-significant difference of .11 SD between the groups. Scarr et al. concluded: “ **An extrapolation from the contrast between extremes within the hybrid group to the average differences between the races predicts that not more than one third of the observed difference between the races could be due to genetic differences. In view of the negligible correlations between estimated ancestry and intellectual skills even this seems unlikely**.” > > It’s easy to see why the results don’t support the conclusion: > > a. According to Scarr et al. the difference between the upper and lower thirds of the distribution was 0.11 SD. Assuming a normal curve approximation, the upper and lower thirds of a distribution are 2.2 SD apart. If the upper and lower thirds are 2.2 SD apart and the correlation between IQ and ancestry is, according to Scarr et al. 0.05, we would expect that the difference between the thirds would be 0.11 SD (2.2 x o.05). So the “negligible” correlation is consistent with the mean difference, which Scarr et al tell us is consistent with a population difference of 1/3rd of a standard deviation – which is hardly negligible. > > b. Now it’s clear that Scarr et al.’s index of ancestry was unreliable so we have to correct for that. Based on partial correlations, Jensen (1981) calculated the validity of the index to be 0.49. We can calculate it alternatively by simply dividing the skin color-ancestry correlation found in the US Black population when using modern methods (0.44) by the skin color-ancestry correlation which Scarr et al. found (.27). We get a validity of .61, which might be an overestimate, as some of the correlation between skin color and Scarr et al.s index of ancestry could be due to the correlation between blood groups and skin color genes as the authors noted. > > c. Using the higher estimated reliability (.61), the corrected mean difference is 0.18 (0.11/.61). > > d. Plugging this into Scarr et al.’s formula above (expected BGH x 0.23 = 0.18), we get a between group heritability of 0.78. > > Quote: “The rough calculation for the estimate of the difference between upper and lower thirds of the black group proceeds as follows. If the resultant difference in standard deviations is 0.9 between the races when the mean difference in degree of Caucasian ancestry is about 0.77 (0.99 – 0.22 = 0.77) then the difference between upper and lower thirds of the black group alone should be about 0.23SD when the difference in Caucasian ancestry is about (0.35 – 0.15) = 0.20. Furthermore, if three-fourths of that mean difference is due to racial genetic differences alone the smallest expected difference is (0.75 x 0.23) = 0.18.” > > Following Scarr et al. we could conclude that given the mean difference between the upper and lower thirds of the Black population and given the commensurate correlation between IQ and ancestry, a genetic difference over one half of a standard deviation seems likely. You can refer to the original paper [here](http://lesacreduprintemps19.files.wordpress.com/2011/07/scarr-1977.pdf). Refer also to Jensen’s technical discussion of it in the G-factor (1998). And to Edward Reed’s discussion of it: Reed (1997) The Genetic Hypothesis: It Was Not Tested but It Could Have Been > [@](#): > > Scarr et al. (1977) used Black twins from the Philadelphia area, and the number (181) was large enough, using both Fy ~ and Fy b of the Duffy group, to give a useful estimate ofP w. Gm serum groups were determined (testing for four factors) and could also have given a useful estimate of P,. Ten other groups were also tested. Scarr et al. attempted to obtain for each individual a measure of individual ancestry to associate with an estimate of cognitive ability, but this measure is deeply flawed. They used an “odds coefficient,” log[AtAzA3…/BtBzB3…], in which A was one ancestral population (e.g., African) and B was the other ancestral population, and the subscripts were the loci of the different blood and serum groups. A t was the frequency of an individual’s phenotype (group) at Locus 1 in Population A, Bt was the frequency of his or her phenotype in Population B at that locus, and so on. This coefficient was intended to give a rank ordering of individuals according to their degree of ancestry from one population, say A. Now consider the effect of one uninformative Locus X, for example the MN blood groups, on this coefficient. Because A/B x varies essentially at random, and Ax/B x multiplies all the other ratios, the odds coefficient acquires considerable randomness. Add the random effects of other only slightly informative loci, such as the ABO, and the coefficient will necessarily lose much of its potential for ancestry identification. Scarr et al.’s (1977) procedure for dealing with zero phenotype frequencies—replacement by .0001- further distorts the coefficient, particularly for the informative Duffy and Gm groups. This is because, with the usual sample sizes, absence of a phenotype at Locus Y does not mean that its true frequency is not of the order of.01 -.001. This procedure would often bias log(A/By) by about ± 1 to ± 2. With the above problems, it is not surprising that the correlations between the odds coefficient and the measures of cognitive skills were nonsignificant; it would be surprising if they were otherwise. (Incidentally, although Scarf et al. thanked me and others for “consultation on the design and analysis of the study” [p. 86], I did not have any part in the design or analysis.) This is yet another one of those often cited studies which, on closer inspection, provides no support for an environmental hypothesis. But yet is continually recycled. It’s amazing. ---
**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, 2:12am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/203 "2012-07-13T02:12:04Z")
> [@Evil\_Economist](#): > > The entire block you posted appears to be from some guy’s blog. > > The Wiki link you posted has the following statement: > > So, agreed, the study didn’t clarify anything. But that’s not good news for the “genetic” team; doesn’t this mean that the evidence for a genetic explanation is precisely…nothing? The authors also noted: “We think that it is exceedingly implausible that these differences are either entirely genetically based _or entirely environmentally based_. The true causes of racial-group differences in IQ, or in any other characteristic, are likely to be too complex to be captured by locating them on a single hereditarianism-environmentalism dimension.” Early childhood experience only explained 13% of the variance in IQ scores by age 17. And the biracial kids had earlier placements than the White kids, so early placement or adoptive experience could not explain that difference. Whatever the case, in my discussion I merely noted that this study was consistent with a genetic hypothesis and argued that it, along with other findings, suggested that the gap could not be explained by home environmental factors. I don’t put much weight on single studies. ---
**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, 2:33am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/204 "2012-07-13T02:33:14Z")
> [@Evil\_Economist](#): > > This kind of sounds to me like you are saying that American people with black skin don’t “share a common genetic heritage.” So, we would not expect “American people with black skin” to “vary in terms of their genetic component of intelligence” because people with black skin do not form a group of “people with similar genetic heritage.” > > Welcome to the club; you are now an “anti-racist”. This is a moronic point. As for “people of color” in general there could be a pleiotropic effect between IQ and skin color, causally leading people with darker skin to have, on average, lower IQs. Alternatively, convergent evolutionary could have selected for lower IQ and darker skin, leading dark people in general to have lower IQs. Alternatively, the darker people in the US could be an unrepresentative sub sample,with respect to IQ, of the dark people in the world. Perhaps only the low IQ coloreds are here. There are a numbers of possible reasons for why “people of color” in the US could be genetically less intelligent than people who lack color. But that’s not what we’re talking about. We are restricting our claims to African Americans, who are defined in terms of genealogy. ---
**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, 2:50am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/205 "2012-07-13T02:50:58Z")
> [@monavis](#): > > I don’t think it is an IQ gap, just the opertunity to have good food etc. growing up, and the way some people think of it. All so called races have high and low IQ people. Judging people by their color is a low IQ way of looking at it! Given the IQ difference, the existence of which is established, not judging people by the color of their skin leads to “disparate impact.” Their are laws against this, which require discrimination on the basis of color. Do you consider this to be justified? In terms of IQ, the variance between to within Blacks and Whites is 20% to 80%. So yes, it’s recognized that all “races have high and low IQ people” and that the difference between is not great. ---
**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, 2:54am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/206 "2012-07-13T02:54:47Z")
> [@tomndebb](#): > > Unquestionably, there are not, so you claim is refuted. Are you saying that there are no breeding populations (i.e., Dobzhansky’s race concept )? I thought so. ---
**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, 3:03am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/207 "2012-07-13T03:03:39Z")
> [@Evil\_Economist](#): > > OK, let’s assume that there is a “a trait common and unique to all West-Africans broadly.” Let’s call this the negative intelligence gene (everything here hypothetical), so that West Africans broadly have an average IQ of 85 and Europeans broadly have an average IQ of 100. > > Does this lead to testable implications? > > Let’s start with this one: does this indicate that people with a mix of West African and European genes should have an average IQ between 85 and 100? Yes, let’s discuss. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [July 13, 2012, 3:04am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/208 "2012-07-13T03:04:38Z")
> [@Chuck11](#): > > 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. Wait, what?! Where are you getting the term “zoological race”?! ---
**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, 3:09am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/209 "2012-07-13T03:09:37Z")
> [@Evil\_Economist](#): > > OK, so let’s examine this, to see if we can find testable implications. > > For our hypothetical “negative intelligence” gene, which of the following statements do you believe to be accurate: > > a) anyone with any West African heritage at all will be affected by the negative intelligence gene (and will have an average IQ of 85) > > b) The more West African heritage a person has, the more likely they are to be affected by the negative intelligence gene. Those affected will have an average IQ of 85 and those unaffected will have an average intelligence of 100 > > c) Anyone with any European heritage at all will be unaffected by the negative intelligence gene > > d) Other The answer is obviously (d) unless you [accept the gene of large effect theory](https://lesacreduprintemps19.files.wordpress.com/2012/05/racial-differences-and-the-probability.pdf). Difference within and between populations are highly polygenic. ---
**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 13, 2012, 4:06am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/210 "2012-07-13T04:06:34Z")
> [@Chuck11](#): > > I discussed this study: > > > [@](#): > > > > Scarr et al. (1977) tested the genetic hypothesis in two ways. First, they looked to see if g was associated with an index of African ancestry and found a statistically non-significant -.05 correlation and, second, they divided their subjects into thirds based on their index of ancestry and compared the g scores of the top third to the bottom third; the latter analysis showed a non-significant difference of .11 SD between the groups. Scarr et al. concluded: “An extrapolation from the contrast between extremes within the hybrid group to the average differences between the races predicts that not more than one third of the observed difference between the races could be due to genetic differences. In view of the negligible correlations between estimated ancestry and intellectual skills even this seems unlikely.” > > > > It’s easy to see why the results don’t support the conclusion: > > > > a. According to Scarr et al. the difference between the upper and lower thirds of the distribution was 0.11 SD. Assuming a normal curve approximation, the upper and lower thirds of a distribution are 2.2 SD apart. If the upper and lower thirds are 2.2 SD apart and the correlation between IQ and ancestry is, according to Scarr et al. 0.05, we would expect that the difference between the thirds would be 0.11 SD (2.2 x o.05). So the “negligible” correlation is consistent with the mean difference, which Scarr et al tell us is consistent with a population difference of 1/3rd of a standard deviation – which is hardly negligible. Everything you said above is wrong. Do you know what statistically insignificant means? In this case it means those numbers cannot be distinguished from zero. To state that those correlations are statistically insignificant and to then use them to perform calculations is just completely and utterly wrong. ---
**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 13, 2012, 4:23am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/211 "2012-07-13T04:23:04Z")
> [@Chuck11](#): > > Reed (1997) The Genetic Hypothesis: It Was Not Tested but It Could Have Been > > This is yet another one of those often cited studies which, on closer inspection, provides no support for an environmental hypothesis. But yet is continually recycled. It’s amazing. And yet when I look at your study I see the following: “The author argues that this error nullifies the negative finding of the studies, and leaves open the question of whether definitive tests of the genetic hypothesis are possible.” So you’ve quoted a paper stating that it might not be possible to link genetics to IQ at all. And it’s especially curious that you would quote this paper immediately after trying to calculate the effects of genetics on IQ(while making a bunch of obvious errors). You have contradicted yourself within one post. ---
**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 13, 2012, 4:31am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/212 "2012-07-13T04:31:46Z")
> [@Chuck11](#): > > The authors also noted: > > “We think that it is exceedingly implausible that these differences are either entirely genetically based _or entirely environmentally based_. The true causes of racial-group differences in IQ, or in any other characteristic, are likely to be too complex to be captured by locating them on a single hereditarianism-environmentalism dimension.” I want the context; link to the paper directly, please. ---
**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 13, 2012, 4:32am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/213 "2012-07-13T04:32:52Z")
> [@Chuck11](#): > > The answer is obviously (d) unless you [accept the gene of large effect theory](https://lesacreduprintemps19.files.wordpress.com/2012/05/racial-differences-and-the-probability.pdf). Difference within and between populations are highly polygenic. So, you think you cannot make the calculations you made in post #202? So, why did you make them? ---
**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 13, 2012, 4:37am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/214 "2012-07-13T04:37:22Z")
> [@Chuck11](#): > > I I don’t necessarily disagree with the NPI’s positions. > [@](#): > > On April 8, 2008, the SPLC’s Mark Potok[3] condemned the National Policy Institute as a “white supremacist” organization, and wrote that its report, The State of White America-2007, “paints ‘a statistical and narrative portrait of the war on white America,’ in the website’s words. Nicholas Stix’s introduction [4] to the article describes the Supreme Court’s 1954 Brown vs. Board of Education ruling outlawing school segregation as ‘arguably the worse [sic] decision in the Court’s 216 year history.’ He claims later civil rights legislation was unconstitutional. ‘\*ntegration and the civil rights movement led directly to the destruction of great cities,’ he concludes.” Let’s clarify; are you a white supremacist? ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [July 13, 2012, 5:29am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/215 "2012-07-13T05:29:40Z")
> [@Chuck11](#): > > Are you saying that there are no breeding populations (i.e., Dobzhansky’s race concept )? I thought so. When Dobzhansky used the word race in the 1920s through 1950s, he was usually describing what we would now call populations and when he did refer to the older understanding of the three or five races, he was simply employing the terminology of the times, before Cavalli-Sforza demonstrated that there was no legitimate scientific support for such broad classifications. The word race too often is used in bait-and-switch tactics where someone gets an agreement that a relatively small, localized population has a trait, using the word race to identify that population, then falls back on nonsense claims about “Caucasians” or “Negroids” when such extremely large groups of populations simply fail to have sufficient coherence to justify lumping them together. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [July 13, 2012, 5:31am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/216 "2012-07-13T05:31:55Z")
> [@BrainGlutton](#): > > Wait, what?! Where are you getting the term “zoological race”?! It has a scatalogical source. 😛 ---
**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 13, 2012, 6:08am UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/217 "2012-07-13T06:08:49Z")
[Here’s](http://www.brookings.edu/views/papers/dickens/20060619_IQ.pdf)an interesting paper: > [@](#): > > All existing data suggest that since the 1960s, black children have made > large IQ gains relative to whites even if the timing of those gains is uncertain. > > … > > The constancy of the black/white IQ gap is a myth. Blacks have gained 5 or 6 IQ > points on whites over the last 30 years. If you’re going to posit a genetic cause for IQ differences between blacks and whites, you’re going to have to explain why that gap is disappearing. My suggestion: genetic mutations affecting all black people that will inexorably lead to flying, invulnerable blacks. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [July 13, 2012, 1:53pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/218 "2012-07-13T13:53:05Z")
> [@Chuck11](#): > > That said, I don’t necessarily disagree with the NPI’s positions. What?! Dude, seriously?! [These](http://www.npiamerica.org/about/) are their positions! > [@](#): > > In this way, the dispossession of White Americans will have catastrophic effects for the entire world, not just for our people. > > As the late Samuel Francis, a co-founder of NPI, noted, > > > [@](#): > > > > If the people or race who created and sustained the civilization of the West should die, then the civilization also will die. > > > > As long as whites continue to avoid and deny their own racial identity, at a time when almost every other racial and ethnic category is rediscovering and asserting its own, whites will have no chance to resist their dispossession. > > Rediscovering our identity—becoming who we are—is the central mission of The National Policy Institute. > > We hope that you will join us in this world-historical struggle—for our people, our culture, our future. They might just as well quote the [Fourteen Words](http://en.wikipedia.org/wiki/Fourteen_words)! :rolleyes: ---
**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, 8:00pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/219 "2012-07-13T20:00:37Z")
> [@BrainGlutton](#): > > Wait, what?! Where are you getting the term “zoological race”?! A google search gives me 338 hits, so I’m not the only one who uses it. Race is a generic term. “Zoological” modifies it. “Zoological race” specifically refers to the race concept in zoology. There are other race concepts in biology, such as ecotype and breeding population. And there are other biologically based races concepts in anthropology, such as Brues’ race concept, which is still cited now and them. My point was that even if there are no “zoological races” there still would be “biological” ones. Precision is important in these discussions. ---
**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 13, 2012, 8:31pm UTC](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877/220 "2012-07-13T20:31:19Z")
Dude, 338 Google hits is basically non-existent, considering more than 75% of those hits are referring to completely unrelated stuff like actual footraces or just spamming word aggregations. [Previous page](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877.md?page=10) [Next page](https://boards.straightdope.com/t/can-the-black-white-racial-iq-gap-in-the-us-be-environmentally-explained/626877.md?page=12)