Ezra Klein asks "How Quickly Do Genes Change?" in response to Andrew Sullivan gushing over Greg Clark's new book, A Farewell to Alms. Clark offers the hypothesis that the industrial revolution in England was catalyzed in part by changes in behavior which might have been reinforced by selection for particular alleles. In terms of the specific hypothesis, I'm skeptical and would probably bet that Clark has overplayed his hand and put too many eggs in one basket. But, in response to Ezra's question I threw down a flurry of comments (with a lot of grammatical errors due to my haste) which you can see over at the post. The short answer of course is:
the rate of change of allele frequencies depends on the parameters
. Molecular genetics is often about positing deterministic biophysical pathways, but evolutionary genetics is just as interested in the fluctuations and variations of alleles over time, and those variations are contingent on a host of factors. There isn't one specific answer, just a range depending on your assumptions or the empirical realities (e.g., selection coefficient, heritability of the character, demographic history, meta-population dynamics, etc.). So whether Clark's hypothesis is right or wrong as an empirical question, not a theoretical one. One can't rule it out a priori.