Open thread, May 17-31 2013

If it's worth saying, but not worth its own post (even in Discussion), then it goes here.

Thought I would repeat something I recently posted buried deep in a digressionary comment thread of an old post:

http://pss.sagepub.com/content/14/6/623.short

http://dl.dropboxusercontent.com/u/67168735/heritability%20of%20iq.pdf

"Socioeconomic status modifies heritability of IQ in young children".

To make a long story short, this analysis of a large cohort of children assigned a 'socioeconomic status indicator' to each family they were following from 0 to 100 based on a large number of factors. They found that the heritability of IQ was a VERY strong positive function of socioenomic status. At the bottom, they think less than 5% of IQ variation is moderated by genetics. At the top of the scale, over 80%.

Obvious interpretation: low socioeconomic status masks genetic predisposition. Alternative restatement: high status environments allow previously cryptic variation to show itself. Low status populations are too genetically diverse for there to be a common factor that doesn't vary between any of them.

I put a HBD chick into play.

16Kaj_Sotala13y

This is, of course, exactly the kind of result that you would expect to get given the way that heritability is defined. When you make environment more uniform in terms of quality, you drive up the heritability, and vice versa. The strength of the effect is still interesting, though.

6Vaniver13y

Is the total amount of variation the same in different populations? How does the magnitude of the variation contributed by genetics compare? (That is to say, one percentage may be very different from another percentage.)