It it difficult to work out what is happening at The Economist. They used to ignore the concept of intelligence, or certainly did not include it in their discussions of economic progress. They never referred to national intelligence levels as a factor in innovation, and did not bother to review those books which linked intelligence and scholastic achievement to a nation’s gross national product. They were the citadel of Blank Slate-ism.
Now things are changing, and today 10 May under the chapter heading “Genes and intelligence” their headline reads “The 3% Solution”.
What they are touting is research which suggests that one gene accounts for 3% of the total variance in intelligence, which is a considerable amount for one little gene. You might imagine I would pounce on this finding as part of “I told you IQ was genetic”. To the contrary, this Damascene conversion of an economics magazine, while welcome, does not blind me to the improbable claims being made.
KL-VS did not curb decline, but it did boost cognitive faculties regardless of a person’s age by the equivalent of about six IQ points. If this result, just published in Cell Reports, is confirmed, KL-VS will be the most important genetic agent of non-pathological variation in intelligence yet discovered.
Gene hunters doing their genome wide searches are happy if they find a collection of genes which each account for a fraction of 1% of the variance. The more genes that get compared to a variable like intelligence the higher the chance of spurious associations. False positives require large sample sizes and 100,000 people is now standard. The Dubal and Mucke study has a sample size of 718. Yes, their techniques are different from GWAS but it is a little early to declare a result.
Perplexed, I decided to get into the Psychological Comments network of loyal readers, and quickly got a response from a notable researcher in the field:
I hope the finding is true — and the mouse story is interesting — but we have reasons to be sceptical because the effect size is so large it should have popped out of GWA studies.
The hunt (for many, many genes of small effect) continues.