Department of Horticulture, Michigan State University, East Lansing, Michigan, USA.
Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, Michigan, USA.
Am J Phys Anthropol. 2021 Jun;175(2):465-476. doi: 10.1002/ajpa.24216. Epub 2021 Feb 2.
Debate about the cause of IQ score gaps between Black and White populations has persisted within genetics, anthropology, and psychology. Recently, authors claimed polygenic scores provide evidence that a significant portion of differences in cognitive performance between Black and White populations are caused by genetic differences due to natural selection, the "hereditarian hypothesis." This study aims to show conceptual and methodological flaws of past studies supporting the hereditarian hypothesis.
Polygenic scores for educational attainment were constructed for African and European samples of the 1000 Genomes Project. Evidence for selection was evaluated using an excess variance test. Education associated variants were further evaluated for signals of selection by testing for excess genetic differentiation (F ). Expected mean difference in IQ for populations was calculated under a neutral evolutionary scenario and contrasted to hereditarian claims.
Tests for selection using polygenic scores failed to find evidence of natural selection when the less biased within-family GWAS effect sizes were used. Tests for selection using F values did not find evidence of natural selection. Expected mean difference in IQ was substantially smaller than postulated by hereditarians, even under unrealistic assumptions that overestimate genetic contribution.
Given these results, hereditarian claims are not supported in the least. Cognitive performance does not appear to have been under diversifying selection in Europeans and Africans. In the absence of diversifying selection, the best case estimate for genetic contributions to group differences in cognitive performance is substantially smaller than hereditarians claim and is consistent with genetic differences contributing little to the Black-White gap.
关于黑人和白人之间智商分数差距的原因，遗传学、人类学和心理学领域一直存在争议。最近，有作者声称，多基因评分提供了证据，表明黑人和白人之间认知表现差异的很大一部分是由于自然选择引起的遗传差异造成的，这就是“遗传假说”。本研究旨在展示过去支持遗传假说的研究在概念和方法上的缺陷。
为 1000 基因组计划中的非洲和欧洲样本构建了教育程度的多基因评分。使用超额方差检验评估了选择的证据。通过测试过度遗传分化（F 值）来进一步评估与教育相关的变体是否存在选择信号。在中性进化情景下计算了人口的预期平均智商差异，并与遗传假说进行了对比。
使用多基因评分进行的选择测试未能发现自然选择的证据，而使用家族内 GWAS 效应大小的偏差较小的方法时也是如此。使用 F 值进行的选择测试也没有发现自然选择的证据。即使在高估遗传贡献的不现实假设下，预期的平均智商差异也远小于遗传学家所假设的差异。
鉴于这些结果，遗传假说至少没有得到支持。认知表现似乎没有在欧洲人和非洲人中受到多样化选择的影响。在没有多样化选择的情况下，对认知表现群体差异的遗传贡献的最佳估计值远小于遗传学家所声称的，并且与遗传差异对黑人和白人差距的贡献很小是一致的。
