Based on the study linking various SNPs (single nucleotide polymorphisms) of the DTNBP1 gene, I created the following chart summarizing data from the DTNBP1 study and the HapMap Project. (Sorry about the horizontal scrollbar.):
|IQ benefit||Asian freq||White freq||Nigerian freq||Asian IQ||Nigerian IQ|
The chart above shows the IQ benefit of carrying at least one uncommon allele, and the percent of population having at least one uncommon allele. The righthand columns calculate the IQ difference with respect to the white population.
The net result shows -6.3 IQ points for the Nigerian population group compared to the whites, and -0.1 IQ points for Asians compared to white. Asians are supposed to have higher IQs than whites, so I suspect that other intelligence genes such as the CHRM2 gene, will be found to boost Asian IQ.
The really strange SNP is rs2619538, because that shows -5.1 IQ for Asians compared to whites. Most of the other SNPs show a higher IQ for Asians and a lower IQ for Nigerians. I wonder what else that SNP does?
DTNBP1 explains 1/3 of the black-white IQ gap.
Looking at the allele frequencies, all but one of the SNPs have the white population group in the middle compared to the Asian and Nigerian population groups, tending to confirm J. Philippe Rushton's r/K selection theory.
Human biodiversity deniers say "races have 99.9% same genes blah blah blah more variance withing races than between races blah blah blah," but as we see, it only takes a few SNPs out of billions to to explain 1/3 of the black-white IQ gap.
I will be studying some of the other IQ genes in the future to get a better picture. I suspect that half of the Asian-white-black IQ gaps will be explained by currently known IQ genes.
More than two years after I wrote this, this post suddenly appeared on the front page of reddit.
I was just playing around with the HapMap project when I wrote this post. Although I do believe that the ability to accurately predict a person's IQ based on their genotype will be possible in the not-too-distant future, there aren't yet enough genes identified in the literature for an armchair geneticist to determine the average racial IQs differences between whites, Asians and Nigerians.
HOWEVER, what the existing research and the HapMap project demonstrate is that (1) various SNPs have been identified which are associated with brain function and intelligence; and (2) the frequency of occurrence of these SNPs differ dramatically between races. I am sure that there will soon be more compelling DNA-based proof that the average black isn't as intelligent as the average white. The non-DNA-based proof is compelling.
You should read my post Response to comments on race and intelligence in which I probably responded to the comment you wanted to write.
I already admitted I was just over-exuberantly playing around with the HapMap project and I’m now aware that the method was flawed. At the blog Gene Expression, you can read a more detailed explanation of why this specific analysis doesn’t prove much.
But once again, the bigger point of it all is that (1) there are SNPs associated with brain function; and (2) these genes have a very different distribution in different racial gene pools. This demonstrates that there’s a sound basis for the theory that IQ differences and other behavioral differences between races has a genetic explanation.