Sunday, April 06, 2008

Swarming loci; the genetics of height   posted by Razib @ 4/06/2008 03:08:00 PM

Identification of ten loci associated with height highlights new biological pathways in human growth & Genome-wide association analysis identifies 20 loci that influence adult height. ScienceDaily has a long review.

Update: I was pretty sure Genetic Future would hit this, so I didn't say much. Well, here's what he notes:
ScienceDaily puts a positive spin on the story ("Scientists are beginning to develop a clearer picture of what makes some people stand head and shoulders above the rest"), but the real story is this: despite the massive scale of these studies, they're still only capturing less than 5% of the total variance in a trait that is almost entirely (90%) genetic. This is a powerful demonstration of the inability of current GWAS technology to access the genetic variants responsible for the vast majority of heritable variation in at least some complex traits, for reasons I have previously discussed in detail.

The bolded parts are exactly right in my estimation; of course nearly a century of biometric analysis of human height should lead us to expect this. In contrast, 50 years ago there was pedigree based work which implied that skin color was going to resolve itself so that about half a dozen loci of large effect explaining most of the variance. That's what we see.

But I think height is important & interesting. Our species has shrunk since the last Ice Age (even modern nutrition hasn't brought us all the way back). Why? Cross-cultural evidence seems to suggest that tall men are more reproductively fit, but the fact that there is a normal range of variation within populations tells us that strong directional selection hasn't been effective over the long term. Otherwise, variation would quickly be exhausted. But it seems likely that some of the between-population differences are due to genetic differences.

Related: Why you be short or tall (well, a little bit) & Why Asians are so short (perhaps).