# From a purely genetic standpoint, how does it make sense that the average IQ of African Ams is 85? **URL:** \ **Category:** Great Debates\ **Created:** [October 23, 2013, 5:08pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041 "2013-10-23T17:08:53Z")\ **Posts on this page:** 20\ **Page:** 13
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [October 28, 2013, 7:40pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/241 "2013-10-28T19:40:35Z")
> [@Ibn\_Warraq](#): > > That’s an extremely odd comment for someone referencing Malcolm Gladwell. > I’ll assume that just as you weren’t aware of Rushton promoting the idea that white men have small penises you weren’t familiar with Gladwell 's 10,000 hour rule. > > According to Gladwell it takes around 10,000 hours to become an elite level basketball player so it makes little sense to reference him when claiming that “the africans” who’d never played basketball would “in short order” beat the Inuit who’d been playing their whole lives. To be clear: I am maintaining that Gladwell is completely wrong. If you don’t have the right genes, no amount of practice will overcome that. The right genes will let you rapidly overtake an individual with crummier genes for that skillset, even if they have substantially more training invested in it. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [October 28, 2013, 7:48pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/242 "2013-10-28T19:48:33Z")
I just like how discussions of “elite” groups (by definition small, unrepresentative and tightly selected) are meant to imply things about large populations. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [October 28, 2013, 7:57pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/243 "2013-10-28T19:57:47Z")
> [@Bryan\_Ekers](#): > > I just like how discussions of “elite” groups (by definition small, unrepresentative and tightly selected) are meant to imply things about large populations. That’s a good point… even if elite NBA players are disproportionately black due to some genetic advantage (and this is far from settled), this says little about any disproportionate athleticism between _average_ black people and average people of another group (like the Inuit). ---
**Author:** ![Budget\_Player\_Cadet](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/budget_player_cadet/32/205_2.png) [@Budget\_Player\_Cadet](https://boards.straightdope.com/u/Budget_Player_Cadet)\ **Post date:** [October 28, 2013, 8:01pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/244 "2013-10-28T20:01:23Z")
> [@Chen019](#): > > I think Rindermann et al found the African average was about 77, while Wicherts found it was about 82. So it’s not that far out from the African-American average. And if you can’t see, immediately, what is wrong with this proposal - if you feel it reasonable to entertain that this figure means what these researchers would imply it means - then I welcome you to join Brazil84 in the pit. ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [October 28, 2013, 8:03pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/245 "2013-10-28T20:03:35Z")
> [@Bryan\_Ekers](#): > > Great. When you find a gene that is a specific and reliable indicator for intelligence, let us know. I don’t think there is any such thing. Use of the term “intelligence” is shorthand for what is essentially a western concept, anyway. What I argue is that different groups have different outcomes for different skillsets because of the substantial contribution that their disparate genes make in addition to the contribution of nurturing. Bodies and minds work differently between individuals, and for groups with long enough separation, average differences among groups appear as the gene pools diverge. When you have a good postulate for why genes related to how our minds work would be exempt from evolution in groups separated for tens of thousands of years when every other characteristic has evidence of having been altered by evolution, let me know. And when you find a good reason why children of black parents who are well-educated and relatively wealthy substantially underscore white and asian children from uneducated and poor families on the SAT, let me know. When you have good data showing no differences among SIRE groups in physiologic functions such as blood levels for testosterone, let me know. When you find a broad pattern anywhere in the world under any political history, any historical context or any dominant population that is an outstanding example of an exception to the generally observed pattern (patterns such as blacks winning sprinting events in numbers disproportionate to the starting pools for that pursuit), let me know. When you have a good study showing that gene clustering by SIRE groups does not occur, and that positive selection pressure is not a reasonable postulate for driving the high penetration in a SIRE group to create that clustering, let me know. It is not necessary to identify an exact geneset to create a reasonable postulate that genes drive outcomes. What is necessary is to normalize for nurturing variables. The “show me the gene” argument is the refuge for those who want to dodge the obvious. I can’t even show you “the” gene for tallness. But I can assure you that tallness is governed by genes as well as nurture, and that different groups have different average heights because (having reasonably accounted for nurture) their gene pools are different. ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [October 28, 2013, 8:06pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/246 "2013-10-28T20:06:33Z")
> [@iiandyiiii](#): > > That’s a good point… even if elite NBA players are disproportionately black due to some genetic advantage (and this is far from settled), this says little about any disproportionate athleticism between _average_ black people and average people of another group (like the Inuit). I take it, then, we won’t see over-representation of black athletes anywhere along the basketball chain until the NBA? It doesn’t exist in grade schools, high schools, colleges and church leagues? ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [October 28, 2013, 8:19pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/247 "2013-10-28T20:19:47Z")
> [@Chief\_Pedant](#): > > The “show me the gene” argument is the refuge for those who want to dodge the obvious. Huh. I always figured gene arguments in general were refuges for people who wanted to dodge the obvious effects of culture and environment. ---
**Author:** ![Hank\_Beecher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hank_beecher/32/7275_2.png) [@Hank\_Beecher](https://boards.straightdope.com/u/Hank_Beecher)\ **Post date:** [October 28, 2013, 8:23pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/248 "2013-10-28T20:23:35Z")
> [@Chief\_Pedant](#): > > I take it, then, we won’t see over-representation of black athletes anywhere along the basketball chain until the NBA? > > It doesn’t exist in grade schools, high schools, colleges and church leagues? ISTM this is proportional to interest. Basketball is wildly popular among white kids, and ubiquitous among black kids. Where the popularity of the sport is more proportional so is the representation, like in baseball, or at the other end of the spectrum, hockey. ---
**Author:** ![SlackerInc](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slackerinc/32/275_2.png) [@SlackerInc](https://boards.straightdope.com/u/SlackerInc)\ **Post date:** [October 28, 2013, 9:19pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/249 "2013-10-28T21:19:30Z")
> [@Bryan\_Ekers](#): > > Huh. I always figured gene arguments in general were refuges for people who wanted to dodge the obvious effects of culture and environment. I don’t know of anyone who completely disregards the importance of environment on one’s intelligence and development. What I do see is people who are more extreme on the other (“nurture”) side, framing the issue in the way Steven Pinker calls the “standard model” or “blank slate.” These people in the radical “nurture” camp (and I was raised by two of them, a sociologist and an anthropologist) almost completely discount genetics outside of extreme cases of retardation. They act outraged by the position of Pinker and others in his camp and cast them as radicals when it in fact is (or should be seen as) the moderate position, finding somewhere between a 40% and 60% role for each side: nature _and_ nurture. Instead, we hear hisses and boos and accusations that our position is racist, fascist, right wing, etc. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [October 28, 2013, 9:31pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/250 "2013-10-28T21:31:00Z")
Tragic, but there’s a distinction to be made between looking at an individual and theorizing that genetics plays a significant role in his or her physical and mental capacities, and looking at an entire society or racial/ethnic group and saying genetics is why they have more or fewer doctors or more or fewer criminals. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [October 28, 2013, 10:00pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/251 "2013-10-28T22:00:32Z")
> [@Bryan\_Ekers](#): > > Tragic, but there’s a distinction to be made between looking at an individual and theorizing that genetics plays a significant role in his or her physical and mental capacities, and looking at an entire society or racial/ethnic group and saying genetics is why they have more or fewer doctors or more or fewer criminals. Something tells me you aren’t going to convince them. Can we go back to “Africa has no cities” or “Africans can’t read- Gotcha!”? Or are we going to move on to the next half-thought-out talking point on the list? ---
**Author:** ![Budget\_Player\_Cadet](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/budget_player_cadet/32/205_2.png) [@Budget\_Player\_Cadet](https://boards.straightdope.com/u/Budget_Player_Cadet)\ **Post date:** [October 28, 2013, 10:45pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/252 "2013-10-28T22:45:17Z")
Those arguing that we shouldn’t need to find a gene: _no_. Either you design a test which effectively eliminates _all_ environmental factors, or you find a gene, because otherwise your theory has _no grounding in reality_. It is all entirely conjecture. And I’m sorry, but conjecture is not good enough, especially given the absolutely ludicrous conclusions many of the “scientific authorities” on your side have offered - “scientific authorities” being researchers often entirely discredited. ---
**Author:** ![Tethered\_Kite](https://avatars.discourse-cdn.com/v4/letter/t/a5b964/32.png) [@Tethered\_Kite](https://boards.straightdope.com/u/Tethered_Kite)\ **Post date:** [October 28, 2013, 11:51pm UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/253 "2013-10-28T23:51:23Z")
> [@SlackerInc](#): > > I don’t know of anyone who completely disregards the importance of environment on one’s intelligence and development. What I do see is people who are more extreme on the other (“nurture”) side, framing the issue in the way Steven Pinker calls the “standard model” or “blank slate.” > > These people in the radical “nurture” camp (and I was raised by two of them, a sociologist and an anthropologist) almost completely discount genetics outside of extreme cases of retardation. They act outraged by the position of Pinker and others in his camp and cast them as radicals when it in fact is (or should be seen as) the moderate position, finding somewhere between a 40% and 60% role for each side: nature _and_ nurture. Instead, we hear hisses and boos and accusations that our position is racist, fascist, right wing, etc. Anecdote: I walked right into this one in 1968. Sociology 101, I a college sophomore who had only just heard of the blank slate concept and to whom it hadn’t yet occurred that there were political implications hidden within. When the young instructor finished his lecture I thought that it gave gave short shrift to genetic influences, so I raised my little smartypants hand and said so. The angry dressing down I got seemed so out of proportion to the innocence and, to me, logical nature of my observation. Made mental note not to challenge the instructors. It took me another couple of years before I figured out the man must have thought I was a Nazi. (At least he treated me with that level of scorn one would reserve for a stupid and rude person.) I had the pleasure a couple of years ago when I ran into him downtown one afternoon of reminding him of that day (which of course he didn’t remember) and asking him if he had some time to discuss his ideas about the blank state as it was today. But he was in a terrible hurry at the moment. 😃 ---
**Author:** ![Chen019](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@Chen019](https://boards.straightdope.com/u/Chen019)\ **Post date:** [October 29, 2013, 2:35am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/254 "2013-10-29T02:35:15Z")
> [@Budget\_Player\_Cadet](#): > > Those arguing that we shouldn’t need to find a gene: _no_. Either you design a test which effectively eliminates _all_ environmental factors, or you find a gene, because otherwise your theory has _no grounding in reality_. It is all entirely conjecture. And I’m sorry, but conjecture is not good enough, especially given the absolutely ludicrous conclusions many of the “scientific authorities” on your side have offered - “scientific authorities” being researchers often entirely discredited. Again, it’s worth repeating that when [polled very few researchers](http://en.wikipedia.org/wiki/The_IQ_Controversy,_the_Media_and_Public_Policy_(book))actually think the gap is entirely due to environmental variation. Even fewer think it is solely due to genetic variation. Far more consider it due to _both_ genetic and environmental variation. In terms of environmental factors note that controlling for [SES does not eliminate gaps](http://commons.wikimedia.org/wiki/File:1995-SAT-vs-Income-Education.png). Also, there is no evidence of any[’X-factor’ that is uniquely depressing scores for some groups](https://www.google.co.nz/?gfe_rd=ctrl&ei=FR5vUpyWHKmN8QexpYH4BA&gws_rd=cr#q=Are+the+Developmental+Processes+Similar%3F+David+C.+Rowe+(1997)+.). Further, heritability is similar across groups. Individual differences are both due to genetic and environmental factors, so if you aggregate those differences it makes sense that part of the difference is due to genetic factors + environmental factors. Certainly, preliminary genomic studies suggest differences seen across countries have some grounding in evolutionary factors. > [@](#): > > These are (most probably) not intelligence coding genes, > but proxies of evolutionary development with potential relevance to cognitive ability. > Correlations and regression analyses with a general developmental indicator (HDI) revealed > that seven haplogroups were empirically important predictors of national cognitive ability (I, > R1a, R1b, N, J1, E, T[+L]). Based on their evolutionary meaning and correlation with cognitive > ability these haplogroups were grouped into two sets. Combined, they accounted in a > regression and path analyses for 32–51% of the variance in national intelligence relative to the > developmental indicator (35–58%). This pattern was replicated internationally with further > controls (e.g. latitude, spatial autocorrelation etc.) and at the regional level in two independent > samples (within Italy and Spain). These findings, using a conservative estimate of evolutionary > influences, provide support for a mixed influence on national cognitive ability stemming from > both current environmental and past environmental (evolutionary) factors. [Haplogroups as evolutionary markers of cognitive ability](https://www.google.co.nz/?gfe_rd=cr&ei=7B5vUrv1A-7C8gfGj4CAAQ#q=haplotypes+evolutionary+cognitive) [2012] Rindermann et al. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 29, 2013, 2:41am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/255 "2013-10-29T02:41:06Z")
> [@Chen019](#): > > Again, it’s worth repeating that when [polled very few researchers](http://en.wikipedia.org/wiki/The_IQ_Controversy,_the_Media_and_Public_Policy_(book))actually think the gap is entirely due to environmental variation. Even fewer think it is solely due to genetic variation. Far more consider it due to _both_ genetic and environmental variation. Again, that was 25 year old horse puckey as pointed before: The survey did not include anthropologists or biologists, and few geneticists. Whoever did this survey is playing loose and fast with what an expert in the matter is, as it was in reality a grab bag of diverse fields what they surveyed. This is using a similar tactic as the survey the global warming deniers did showing that 32000 “experts” do not see that humans are causing the current warming that is being observed: [http://climatecrocks.com/2010/01/09/32000-scientists/](http://climatecrocks.com/2010/01/09/32000-scientists/) So, what you had there was just an example on avoiding the surveying of most of the experts that count to get the results they wanted. ---
**Author:** ![Chen019](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@Chen019](https://boards.straightdope.com/u/Chen019)\ **Post date:** [October 29, 2013, 2:49am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/256 "2013-10-29T02:49:02Z")
[quote=“GIGObuster, post:255, topic:672041”] … That’s a good point, they should do the survey again considering those fields. The survey considered the following. > [@](#): > > The 1020 experts were chosen randomly from the following professional bodies: > > American Educational Research Association (120) > National Council on Measurement in Education (120) > American Psychological Association: > Development psychology division (120) > Educational psychology division (120) > Evaluation and Measurement division (120) > School psychology division (120) > Counseling psychology division (60) > Industrial and organizational psychology division (60) > Behavior Genetics Association (60) > American Sociological Association (education) (60) > Cognitive Science Society (60) What’s interesting is that these aren’t exactly groups of extremists or quacks - if evidence of a purely environmental explanation was available I’m sure more would have gone with that. The reason they didn’t is presumably the same reason to date environmental explanations have been inadequate. None of them explain the gaps. They’re also increasingly untenable in light of genomic research, group differences in brain size etc. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 29, 2013, 3:03am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/257 "2013-10-29T03:03:48Z")
> [@Chen019](#): > > That’s a good point, they should do the survey again considering those fields. The survey considered the following. > > What’s interesting is that these aren’t exactly groups of extremists or quacks - if evidence of a purely environmental explanation was available I’m sure more would have gone with that. > > The reason they didn’t is presumably the same reason to date environmental explanations have been inadequate. None of them explain the gaps. > > They’re also increasingly untenable in light of genomic research, group differences in brain size etc. Not good enough, as others pointed in a different thread you are resorting to arguments from ignorance, made worse by the fact that most of the ones in the survey are also mostly ignorant of that the genetic field is doing. Another thing one should consider is that 25-30 years ago a lot of evidence was found to undermine many of the assumptions of the differences among humans, particular the differences in intelligence. A survey then is more likely to catch the view of the “old guard” when the new one was just coming about. And recently there is even more evidence that environmental explanations enter into the picture with a vengeance. [http://online.wsj.com/news/articles/SB10001424127887324492604579083060346652476](http://online.wsj.com/news/articles/SB10001424127887324492604579083060346652476) > [@](#): > > We all notice that some people are smarter than others. You might naturally wonder how much these differences in intelligence depend on genes or upbringing. But that question, it turns out, is impossible to answer. > > That’s because changes in our environment can actually transform the relationship among our traits, our upbringing and our genes. > [@](#): > > In the latest issue of Psychological Science, Timothy C. Bates of the University of Edinburgh and colleagues report a study of the relationship among genes, SES (socio-economic status, or how rich and educated you are) and IQ. They used statistics to analyze the differences between identical twins, who share all DNA, and fraternal twins, who share only some. > > When psychologists first started studying twins, they found identical twins much more likely to have similar IQs than fraternal ones. They concluded that IQ was highly “heritable”—that is, due to genetic differences. But those were all high SES twins. Erik Turkheimer of the University of Virginia and his colleagues discovered that the picture was very different for poor, low-SES twins. For these children, there was very little difference between identical and fraternal twins: IQ was hardly heritable at all. Differences in the environment, like whether you lucked out with a good teacher, seemed to be much more important. > > In the new study, the Bates team found this was even true when those children grew up. IQ was much less heritable for people who had grown up poor. > [@](#): > > But for poor children, haphazard differences in educational opportunity swamp genetic differences. Ending up in a terrible school or one a bit better can make a big difference. And poor children have fewer opportunities to tailor their education to their particular strengths. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [October 29, 2013, 3:14am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/258 "2013-10-29T03:14:13Z")
> [@Chen019](#): > > Certainly, preliminary genomic studies suggest differences seen across countries have some grounding in evolutionary factors. > > [Haplogroups as evolutionary markers of cognitive ability](https://www.google.co.nz/?gfe_rd=cr&ei=7B5vUrv1A-7C8gfGj4CAAQ#q=haplotypes+evolutionary+cognitive) [2012] Rindermann et al. [_Very_ preliminary studies](https://lesacreduprintemps19.files.wordpress.com/2012/05/haprinderm.pdf)…: > [@](#): > > The first limitation of this study is geographic range as haplogroup frequency data were only available for a relatively small number of countries restricted to Europe, the Middle East and North Africa. > […] > The second limitation lies in the analysis of only male lineages, as genes relevant to cognitive development will stem from maternal as well as paternal lineages. Third, single haplogroups are heterogeneous, being composed of a number of diverse subclades, which may in some cases have experienced diverse selective pressures. > […] > This leads to the fourth caveat as contemporary cognitive ability distributions across countries do not necessarily correspond to past environmental challenges and human accomplishment three to thirty thousand years ago: in the meantime there have been larger migrations, in which one set of people was replaced by another or merged via admixture with others. There are also selective pressures operating within countries, which are thought to have positively or negatively altered ability levels over relatively short periods of time (Woodley, 2012). Therefore not only absolute levels (Flynn-effect) but also differences between nations are at least somewhat subject to change. > Fifth, while this study sheds light on possible evolutionary influences on national differences in cognitive ability today, it tells us nothing about the genetic basis (i.e. common polymorphisms) of intelligence differences, which thus far remain largely unidentified (those that have been identified explain only a small fraction of variance) (e.g. Deary, 2012; Meisenberg, 2003). Therefore, while these findings are intriguing, there can be no certainty about the ways in which genes influence the neurological processes and structures undergirding cognitive ability until the genes responsible are elucidated. The missing link still needs to be found. ---
**Author:** ![Chen019](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@Chen019](https://boards.straightdope.com/u/Chen019)\ **Post date:** [October 29, 2013, 3:14am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/259 "2013-10-29T03:14:18Z")
> [@GIGObuster](#): > > Not good enough, as others pointed in a different thread you are resorting to arguments from ignorance, made worse by the fact that most of the ones in the survey are also mostly ignorant of that the genetic field is doing. > > Another thing one should consider is that 25-30 years ago a lot of evidence was found to undermine many of the assumptions of the differences among humans, particular the differences in intelligence. A survey then is more likely to catch the view of the “old guard” when the new one was just coming about. And recently there is even more evidence that environmental explanations enter into the picture with a vengeance. Actually, the last 25-30 years far more evidence has come in to support the likelihood of a genetic basis for individual and group disparities. For instance, in the 1980’s there was great sceptism about twin/adoption studies following the Cyril Burt controversy. Since then there have been thousands of twin/adoption studies which suggest genes play a role in individual differences. Even Eric Turkheimer, whose research noted that heritability was particularly low in poor environments (similar to Bates research you mention), has commented that all behavioural traits are heritable. On top of that the assumption that there has been little genetic change in humans over the past 50,000 years, has been turned on its head. There has been [accelerated change as groups adapted to different environments](http://www.nytimes.com/2006/03/12/weekinreview/12wade.html?pagewanted=all&_r=0). One of the obvious differences I noted above was brain size which is linked to cognitive abilities. The Australian Aborigines are a classic example, with a larger visual cortex and greater spatial memory. That’s not to deny environmental factors - but as noted above - group differences persist and even increase as you control for socio-economic background. ---
**Author:** ![Chen019](https://avatars.discourse-cdn.com/v4/letter/c/f19dbf/32.png) [@Chen019](https://boards.straightdope.com/u/Chen019)\ **Post date:** [October 29, 2013, 3:21am UTC](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041/260 "2013-10-29T03:21:20Z")
> [@Darwins\_Finch](#): > > [_Very_ preliminary studies](https://lesacreduprintemps19.files.wordpress.com/2012/05/haprinderm.pdf)…: Well yes, although they’re only just identifying gene variants for height - which has similar heritabilty to cognitive ability. Steve Hsu [estimated that would take about 10 years to figure out as cost of sequencing falls](http://infoproc.blogspot.co.nz/2011/05/height-breeding-values-and-selection.html): > [@](#): > > 1. Although known alleles for height only account for 5-10% of variance (out of the expected 80-90%), it is very plausible that loci of smaller effect or MAF (minor allele frequency) account for the “missing heritability”. We still lack sufficient statistics to detect most of the individual loci of this type, but it’s a matter of time. See beautiful paper from Visscher’s group. The results described below suggest that loci just below the (arbitrary) significance threshold currently in use might also be height associated. There is a whole distribution of loci with smaller effect sizes and MAF that are just waiting to be discovered – we have only found the tip of the iceberg. > > 2. Even with only a fraction of total additive variance identified, one can still make estimates of breeding value for groups by simply computing the prevalence of known associated loci in each group. How indicative these (large effect/MAF) loci are of the actual breeding values can’t be answered a priori, but I would bet they are a good indicator, and this seems to be the case for height. > > 3. If the results on selection hold up this will be clear evidence for differential selection between groups of a quantitative trait (as opposed to lactose or altitude tolerance, which are controlled by small sets of loci). We may soon be able to conclude that there has been enough evolutionary time for selection to work within European populations on a trait that is controlled by hundreds (probably thousands) of loci. > > 4. With luck we might get to this level of analysis for g in the next 5-10 years. (I originally wrote 3-5 years but one of my more sober collaborators convinced me that would be quite unlikely!) > > \*Genetic Inference: … Europeans differ systematically in their height, and these differences correlate with latitude. The average Italian is 171cm, whereas the average Swede is a full 4cm taller. Are these differences genetic? Have they been under evolutionary selection in recent human history? > > Michael Turchin gave some pretty convincing answers to these questions, using genetic data from the 129 thousand individuals in the GIANT consortium. He compared the frequencies of alleles that are known to increase height, and found that they are more common in Northern Europe. Interestingly, he found the same relationship for alleles that have weaker evidence for height association, showing that there are still a large number of common height variants hiding in the genome, which are also more frequent in Northern Europe. > > Height differences are thus heritable, but have they been under evolutionary selection? Or are these differences merely down to genetic drift? This can also be tested using the GIANT data, which shows significant statistical evidence of selection on height variants in recent history. On top of that, the magnitude of the selection is correlated with the effect size of the height variant, providing strong evidence that these variants are being selected specifically for their impact on height. > > This is a textbook example of how an evolutionary study should be done; you show a phenotypic difference exists, that it is heritable, and that it is under selection. This opens the question as to why height has been selected in Northern Europe (or shortness in Southern Europe). Could the same data be used to test specific hypotheses there? \* [Previous page](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041.md?page=12) [Next page](https://boards.straightdope.com/t/from-a-purely-genetic-standpoint-how-does-it-make-sense-that-the-average-iq-of-african-ams-is-85/672041.md?page=14)