IQ and genetics

Just watched an interesting lecture on IQ and genomics which makes a number of interesting claims. First, that IQ is as inheritable as height, which is to say that genes are 70% responsible. Second, that it appears to be the result of many different genes, each of which contributes a little bit. (With height, they’ve found 200 such genes.) And third, that although no IQ genes have been discovered, we’ll likely have discovered many of them within the next decade.

This raises many interesting questions, but from an evolutionary standpoint, I see one big one. If IQ is mostly genetic, and it is a major influence in life success (both of which are claimed), why isn’t everyone high-IQ? Is there an evolutionary advantage to a lower IQ (e.g. lower caloric requirements, thus more likely to survive a famine; or lower birthrate?)

This also raises some interesting quandaries. It’s standard practice to do genetic testing on fetuses, to screen for particularly nasty disorders. It’s possible to sequence the entire fetal genome. By the time my kids are grown up, there’s a good chance they’ll be able to do prenatal IQ testing which won’t be as accurate as a real IQ test, but will have decent predictive power.