Genes 2 Brains 2 Mind 2 Me

Image by Colin Purrington via Flickr

Just piling on to the many comments on today’s NY Times profile of David Goldstein who justifiably points out a dearth of whole-genome-snp-scanning success. One interesting debate is whether natural selection had anything to do with expunging the much sought-after (impossible to find) deleterious, disorder-promoting variants (he suggests yes) which means that whilst separate human cultures adapted to separate climate, predators, diets etc. one might expect to identify separate genetic variants that define racial or cultural subgroups (he says no). Huh?

According to the article, Goldstein “says he thinks that no significant genetic differences will be found between races because of his belief in the efficiency of natural selection. Just as selection turns out to have pruned away most disease-causing variants, it has also maximized human cognitive capacities because these are so critical to survival. “My best guess is that human intelligence was always a helpful thing in most places and times and we have all been under strong selection to be as bright as we can be.””

We have a free and open article describing the relationship of a common variant in the COMT gene with human intelligence, which is also supported by a recent meta-analysis on COMT. These findings certainly do not refute Dr. Goldstein’s conclusions, but rather make me wonder why the common valine/methionine variant in COMT might exert a tiny, but measurable, effect on intelligence. Balancing selection possibly ?