Genetics of IQ: not so simple as one gene or SNP

How far can reductionist eliminative science go ? Are we ever going to be able to explain the complexities of intelligence down to the function of just one gene, or even the more closely examined Single Nucleotide Polymorphism?

I’m generally suspect whenever there’s an effort to explain the complex biological process of behavior, which involves more than one dynamically interacting unit, by trying to identify the presence of just one player.

At least there is a debate (behind the scenes) about whether these types of studies are scientifically legitimate.  And although I have been convinced of simple molecular mechanisms that influence organism behavior, and even those responsible for the progression of disease, identification of genes related to intelligence are still a murky water to attempt to glean any scientific certitude. There are just too many factors that influence intelligence, and at least half of them aren’t reducible to genetic factors, they reside in the environment.

For those who believe that IQ is purely environmental and not genetic, any validation might be short lived because these authors did replicate the recent finding that genetic variants explain about 50% of the variance in IQ. Looking at all SNPs together, there was a strong correlation between “genetic similarity” and similarity in IQ. That independently confirms what the much-criticized twin studies of IQ said – that IQ is about 50% heritable.

For those of us that believe in the genetic origin of intelligence, this study suggests that we simply still have no idea what the important genes really are, yet.  It seems that much of the prior studies have been flawed in some critical ways that make their results irreproducible. This sadly means we’ll probably have tens of hundreds of sensational studies and articles written before we have some consensus on which genes seem to have any effect at all.

And the mill keeps turning…


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You have probably noticed the trend of newspaper articles describing the genetic basis of some particular trait. “Now we know the genetic basis of (altruism)(risk-seeking)(happiness)(religiousity)!” These are all published in legit science journals and come with the stamp of approval of Real Science.

But behind the scenes has been a big scientific debate about whether these types of studies are scientifically legitimate. And now it’s starting to seem like a lot of them are wrong.

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