Posted on April 1, 2017

The Genetic Potential for Intelligence

Christopher McCallum, American Renaissance, April 1, 2017

For the general public, the question of whether genes contribute to a person’s intelligence is a matter of controversy. Among intelligence researchers, there is no doubt that variation in intelligence is partly attributable to genes. In fact, the purpose of the very first twin study, done back in 1924, was to study the contribution of genes to intelligence.

Today, researchers can predict how similar the IQ scores of people will be based on how similar their genes are. Such work has confirmed what twin studies have long shown: In adulthood, the majority of variation in intelligence is caused by genes. We now know about many genes that can be used to predict intelligence. Geneticists can determine which version of these genes someone has and, based on how many IQ-enhancing and IQ-deflating gene variants there are, assign a “polygenic score” (a score based on the effect of many genes) that correlates at about 0.3 with IQ scores, which is moderate by conventional standards.

If ancient DNA is sufficiently well preserved, we can make similar comparisons between people who are alive today and people who lived thousands of years ago. This would be an interesting way to judge the extent to which the history of human progress may be the history of the biological evolution of intelligence. Of course, in some sense, everyone knows the two are related. Humans have evolved to be more intelligent than chimps; we have great civilizations and chimps do not. However, many people think that important genetic changes to humans stopped around 100,000 years ago, or that evolution is so slow that even if it has not stopped, the difference between now and then is negligible.

In fact, standard equations from population genetics suggest that evolution can have significant effects in five or ten generations. Sophisticated analysis can determine the relative ages of different genetic clusters in the modern human genome, and such studies have shown that ever since the Neolithic Revolution of approximately 10,000 years ago, the human genome has been changing 100 times faster than what normally occurred during evolution. It was only after the Neolithic Revolution that important traits such as lactose tolerance and the white skin of Europeans appeared. It is therefore reasonable to suggest that our genetic potential for intelligence may have changed recently, too.

This was the focus of a recent paper by Dr. Michael Woodley and his colleagues. First, they tested the DNA of 99 ancient Eurasians who lived between 2540 B.C. and 809 A.D. to determine their “polygenic scores” for intelligence, based on three sets of genes known to predict intelligence. They then compared these scores to a sample of contemporary Europeans. For all three sets of genes, modern genomes had a higher polygenic score. The ratio of IQ-enhancing gene variants to IQ-depressing gene variants was higher in contemporary European genomes than in ancient ones. This strongly suggests that modern Europeans have higher genotypic intelligence. Dr. Woodley’s team found a positive correlation between the age of an ancient genome and its polygenic score, which suggests that genotypic IQ increased somewhat linearly over time.

Why would Europeans have evolved to be smarter than they were 2,000 years ago? At the group level, populations of smarter people may have been more likely to make technological innovations which helped them outfight and outbreed other groups. At the individual level, we know today that IQ is an excellent predictor of job performance as well as scientific innovation, so there is reason to think it might have been true then, too.

More productive people are often wealthier, and if intelligence led to wealth in the past as it does today, it probably led to longer lives and larger families. The work of economist Gregory Clark demonstrates that this was the case for much of English history. During the centuries preceding the Industrial Revolution, differential survival and fertility rates led to poor people being bred out of the population and replaced by the sons and daughters of the wealthy. Prof. Clark argues that this eugenic process partly explains why the Industrial Revolution took place in the West rather than somewhere else.

In this sense, Western civilization and Western man were several thousand years in the making. Unfortunately, today we may be undoing this work. Multiple studies in several different nations have shown the higher the genetic potential for intelligence, the fewer children a person is likely to have. Partly this is because intelligent people put off marriage until they complete their education, which increasingly includes graduate school. By this time, many highly intelligent people don’t have all that many years left for child rearing. At the same time, in First World countries the welfare state lets even poor people have as many children as they want.

Until very recently, large improvements to the environment masked this fall in genotypic intelligence. Improved nutrition and education resulted in higher tested levels of intelligence even though the genetic potential for intelligence was declining. This rise, known as the Flynn effect, occurred all over the world for most of the 20th century and led to measured IQ rising by about 3.5 points per decade. However, the effects of better nutrition and education have reached their limit and the rise seems to be over. Recent studies have shown a decline in IQ in Britain, France, Norway, Denmark, the Netherlands, and Estonia. Fortunately, this new decline in genotypic intelligence is not very large. Given the current association between IQ and fertility, we are estimated to lose roughly 0.82 genotypic IQ points per generation in the United States.

If current trends continue, we will lose just over 15 points of genotypic IQ in 19 generations, or about 400 years. That is roughly the IQ gap between blacks and whites in America, and about half the gap between Europeans and Africans. Some people argue that evolution is so slow it could not possibly have produced the black-white IQ gap. In fact, evolutionary forces at work today could produce a gap of this size in as little as 19 generations, and Europeans left Africa somewhere between 2,000 and 4,000 generations ago.

The egalitarian case is especially difficult to make if the high genotypic IQ of Europeans was achieved in the last few thousand years. If civilization both leads to and is the result of gradual increases in genotypic IQ, it is hard to see how Africans and Europeans could be exactly equal; Europe produced a rich civilization whereas Africa did not.

More generally, if genotypic intelligence is as flexible as it seems to be — if it rises and falls over the centuries due to slight associations between IQ and fertility — then it would be truly miraculous if, at this very moment in time, all the races just happened to have landed on the exact same average level of genotypic intelligence.

The foundation of modern political thought is based on a cosmic coincidence for which there is absolutely no evidence. Research on the genetics of intelligence is steadily attacking that foundation.