As previously noted, J. Philippe Rushton has made the argument that the brain size of “Blacks” is about 1267 cc’s, and for whites it is about 1347 CC’s. It has also been noted that Rushton claims that the average IQ of Blacks is 85 and he average IQ of whites is 100. But does Rushton say that there is a link between the two?
Yes, explicitly so. In his widely distributed editions of Race, Evolution, and Behavior : A Life History Perspective (2nd Special Abridged Edition), Rushton makes the claim that the African IQ is 70, and that the reason that “Black” American IQ is 80 is because of the genetic admixture of Africans and Whites to form the subgroup African-American.
So the Rushton model is very clear: Genes cause differences in brains that are manifest as brain size differences that can be sorted out by race. These brain differences then cause differences in IQ that can be sorted out by race. The close connection between genes on one hand and brain size and IQ on the other hand is so tight and so bound by racial membership that one could actually predict (based on genetic studies he cites) that the African American IQ would be 85 on average. And it is.
It is important to note that most racist (as in race-based, and race presumptive) studies in psychology and related fields that assert the close connection that Rushton makes in his work take this association as strong and well proven. In other words, most studies that link brain size, race, and IQ or some combination thereof either directly or indirectly use these results without any sort of negative criticism.
Or at least, I have been unable to find any such criticism in the mainstream race-based literature.
Therefore, we have to assume that Rusthon’s model represented by the data shown in the above table and as outlined in Race Evolution and Behavior (any edition) is either very well established and virtually unassailable, or has simply been accepted uncritically because it is convenient to do so (and perhaps an example of the phenomenon sometimes called “Aggregation of Evidence” also knon, in the Evolution-Creationism debate, as the “Gish Gallop“.) Selectively picking and choosing among varied evidence, and then constantly repeating those selected (or biased) conclusions can produce what looks like a “lot” of “science” supporting a particular conclusion. Are those who support Rushton’s model doing any of this, or are they carrying out valid scientific research in a fair and accurate fashion?
How can IQ be so different between these different groups, and still be genetic? Intelligence is said to be the hallmark of the human species, but this is a big difference in intelligence. Rushton accounts for this by making the specific claim that Africans and non-Africans split from each other about 200,000 years ago, and that it is likely that evolution is a progressive process with change happening in the direction, long term, of a particular ideal of “advancement.” Specifically, Whites are more evolved in the ‘advanced’ direction while Africans remain primitive.
Well? Is the research unassailable? If not, what’s wrong with it? Are the brain size measurements accurate and valid? Are the IQ measures valid? Is the link between brain size and IQ direct (i.e., measured on the same samples)? Is the brain size to IQ link validated? Is the gene to brain size or IQ link validated? Does evolution work the way Rushton claims it works?