(based on article in The Scientist)
About half of intelligence differences between individuals can be attributed to genetics—specifically, the sum of many small effects from hundreds or even thousands of genes.
“The value of this paper is that it is the first clear and empirical demonstration that part of intelligence comes down to something which is writ in DNA,” said Patrick Sullivan, a psychiatric geneticist at University of North Carolina Chapel Hill, who was not involved in the study.
This may well elicit as much anti science on the left as global warming has created on the right.
In his book, “The Mismeasure of Intelligence,” Stephen Jay Gould . an outspoken evolutionary biologist and a liberal, derided the idea of genetics controlling intelligence as bad science contaminated by racism.
All this came to a head when a former professor of mine, Harvard psychologist Richard J. Herrnstein (deceased before the book was released) and American Enterprise Institute political scientist Charles Murray, published their best selling book “The Bell Curve.” The central claim for Herrnstein and Murray was that the genetic component of intelligence is a critical predictor of social and economic status. From Wikipedia: “The book also argues that those with high intelligence, the “cognitive elite“, are becoming separated from those of average and below-average intelligence, and that this is a dangerous social trend with the United States moving toward a more divided society similar to that in Latin America.”
The new study explains why we have never found a single “intelligence gene”but also says Gould was wrong. It appears, at least in this sample of about 3,500 adults aged 18 to 90 from the United Kingdom and Norway, that hundreds or even thousands of genes each contribute a small amount to intelligence.
Put another way, family does matter … at least among older white folks in Northern Europe. .
Some geneticists will argue that the study is flawed because the researchers sampled only a small subset of markers in the human genome. These markers, called “single nucleotide polymorphisms (SNPs), are not actually genes. Instead SNPs are frequent .. usually non functional, variations in DNA sequence. Because these variations are not functional, they are common and allow us to look at how different bits of the DNA get passed in families. Put another way, … SNPs can only trace genes that most of which are not in the actual genes that are fairly common.
SNPs, however, can mark pieces of DNA that do contain functional mutations. Recent studies suggest that most familial variation is not due to the common SNPs but to much rarer mutations do affect gene function. Because many different rare variants can affect any one gene, familial properties may exist that can not be detected by SNPs.
The bottom line is that this study, assuming it is reproducible, suggests that intelligence, like athletic prowess in horses, does have a large genetic component. The left is likely to deny this because we worry that the facts will lead to eugenics and racism. The eugenics is, of course, quite possible and we could learn that racial groups differ in some degree in natural intelligence. Unfortunately for America’s persistent racists, their definition of race by skin color is what it appears to be … bigotry.
Davies, G., et. al, “Genome-wide association studies establish that human intelligence is highly heritable and polygenic,” Molecular Psychiatry, doi: 10.1038/mp.2011.85, 2011.