This commentary highlights previous literature focusing on cultural and environmental explanations for the racial/ethnic group hierarchy of intelligence. Assumptions underlying definitions of intelligence, heritability/genetics, culture, and race are noted. Historical, contextual, and testing issues are clarified. Specific attention is given to studies supporting stereotype threat, effects of mediated learning experiences, and relative functionalism. Current test development practices are critiqued with respect to methods of validation and item development. Implications of the genetic vs. culture-only arguments are discussed with respect to the malleability of IQ. Rushton and Jensen (2005) review decades of literature to support a genetic basis for the racial/ethnic group hierarchy in intelligence, a position they have held unwaveringly for over 30 years. Their report gives little mention to findings that point to the impact of environment and race (i.e., race as a social construction) on intellectual development or performance—what they term the culture-only perspective. We are not among the culture-only adherents as characterized by

argument that the long-standing, worldwide Black–White average differences in cognitive ability are more plausibly explained by their hereditarian (50 % genetic causation) theory than by culture-only (0 % genetic causation) theory. This commentary evaluates the relevance of their evidence, the overall strength of their case, the implications they draw for public policy, and the suggestion by some scholars that the nation is best served by telling benevolent lies about race and intelligence. Rushton and Jensen (2005) review the last 30 years of evidence on an important but spurned question: Is the average Black–White difference in phenotypic intelligence partly genetic in origin? Much relevant scientific evidence has accumulated since Jensen first asked the question in 1969, but openly addressing it still seems as politically unacceptable today as it was then. Taking the question seriously raises the possibility that the answer might be yes, which for some people is unthinkable. It is therefore no surprise that such research and researchers are often evaluated first against moral criteria and only secondarily, if at all, against scientific ones. My commentary therefore examines the Rushton–Jensen article against both the scientific and moral criteria typically applied to such work. The Hereditarian Hypothesis: What Is It? Rushton and Jensen’s (2005) hereditarian hypothesis is that Black–White differences in general intelligence (IQ, or the general mental ability factor, g) are “substantially ” genetic in origin, which they quantify as 50 % genetic and 50% environmental. They specify 50 % genetic because they hypothesize that race differences are simply aggregated individual differences and because researchers commonly summarize within-group IQ heritability as 50%. Rushton and Jensen do not attempt to prove conclusively a genetic component but to show that their hypothesis is more plausible than the culture-only hypothesis long favored by social scientists, which entails 0 % genetic and 100 % environmental causation.

African-Americans and Whites were asked to solve problems typical of those administered on standard tests of intelligence. Half of the problems were solvable on the basis of information generally available to either race and/or on the basis of information newly learned. Such knowledge did not vary with race. Other problems were only solvable on the basis of specific previous knowledge, knowledge such as that tested on conventional IQ tests. Such specific knowledge did vary with race and was shown to be subject to test bias. Differences in knowledge within a race and differences in knowledge between races were found to have different determinants. Race was unrelated to the g factor. Cultural differences in the provision of information account for racial differences in IQ.

J. P. Rushton and A. R. Jensen (2005) ignore or misinterpret most of the evidence of greatest relevance to the question of heritability of the Black–White IQ gap. A dispassionate reading of the evidence on the association of IQ with degree of European ancestry for members of Black populations, convergence of Black and White IQ in recent years, alterability of Black IQ by intervention programs, and adoption studies lend no support to a hereditarian interpretation of the Black–White IQ gap. On the contrary, the evidence most relevant to the question indicates that the genetic contribution to the Black–White IQ gap is nil. Rushton and Jensen’s (2005) article is characterized by failure to cite, in any but the most cursory way, strong evidence against their position. Their lengthy presentation of indirectly relevant evidence which, in light of the direct evidence against the hereditarian view they prefer, has little probative value, and their “scorecard ” tallies of evidence on various points cannot be sustained by the evidence. The Current Difference in Intelligence Between Blacks and Whites One of the most serious misrepresentations in Rushton and Jensen’s (2005) article is their claim that the current difference in IQ between Blacks and Whites is slightly more than 15 points, or 1 standard deviation. The best evidence we have indicates that that value is out of date and that the Black–White IQ gap has lessened considerably in recent decades (Grissmer, 1994; Grissmer, Flanagan, &

arising from their analysis of alleged genetic bases for group mean differences in IQ. This article argues that none of these implications in fact follow from any of the data they present. The risk in work such as this is that public-policy implications may come to be ideologically driven rather than data driven, and to drive the research rather than be driven by the data. The quest to show that one socially defined racial, ethnic, or other group is inferior to another in some important way, such that “the public must accept the pragmatic reality that some groups will be overrepresented and other groups underrepresented in various socially valued outcomes ” (Rushton & Jensen, 2005, p. 283), has what I believe to be a long, sad history. Since ancient times, cynical political, religious, and other leaders have used such arguments to justify discriminatory ideological positions. Does science want to provide them the ammunition? Scientists might argue that their work is value free and that they are not responsible for the repugnant or even questionable values or actions of opportunistic

In a previous study (Rushton & Jensen, 2005), we examined 10 categories of technical research and concluded that the mean Black-White IQ difference in the United States is about 80% heritable. We reviewed evidence that (a) the distribution of IQ scores around the world shows averages of 106 for East Asians, 100 for Whites, 85 for U.S. Blacks, and 70 for sub-Saharan Africans; (b) race differences are most pronounced on the more g-loaded subtests (g being the general factor of mental ability); (c) race differences are most pronounced on the subtests whose scores show the most heritability; and (d) racial differences in brain size parallel the IQ differences. We also reviewed corroborating studies of (e) racial admixture, (f) trans-racial adoption, (g) regression to different racial means, (h) 60 related life-history traits, (i) human origins, and (j) the inadequacy of environmental explanations of the racial IQ difference. (In Africa,

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Despite repeated claims to the contrary, there has been no narrowing of the 15- to 18-point average IQ difference between Blacks and Whites (1.1 standard deviations); the differences are as large today as they were when first measured nearly 100 years ago. They, and the concomitant difference in standard of living, level of education, and related phenomena, lie in factors that are largely heritable, not cultural. The IQ differences are attributable to differences in brain size more than to racism, stereotype threat, item selection on tests, and all the other suggestions given by the commentators. It is time to meet reality. It is time to stop committing the “moralistic fallacy ” that good science must conform to approved outcomes. In our target article (Rushton & Jensen, 2005), we proposed a hereditarian model—50 % genetic–50 % environmental—to explain the 15- to 18-point average IQ difference (1.1 standard deviations) between Blacks and Whites. We reviewed the worldwide distribution of test scores, the g factor of mental ability, the heritability of within- and between-groups differences, the relation of brain size to intelligence and of race differences in brain size, regression to the mean, crossracial