Sorry for the light posting of late. I’ve been down with the flu.

Be sure to read Nicholas Wade’s Sunday New York Times article,  The Twists and Turns of History, and DNA,  which follows Gregory Cochran’s lead in outlining the role of evolution in recent human history.  The centerpiece is a recently published analysis by population geneticist, Jonathan Pritchard, which found "700 regions of the genome where genes appear to have been reshaped by natural selection in recent times." In case you’re wondering what "recent" means in this context, note that for East Asians the average date of the formative "selection events" was just around 6,600 years ago. 

Wade is, of course, well attuned to the sociopolitical discomfiture attending consideration of the sociobiological inconstancy of human nature, and he frames the news with requisite delicacy:

Trying to explain cultural traits is, of course, a sensitive issue.
The descriptions of national character common in the works of
19th-century historians were based on little more than prejudice.
Together with unfounded notions of racial superiority they lent support
to disastrous policies.

But like phrenology, a wrong idea that
held a basic truth (the brain’s functions are indeed localized), the
concept of national character could turn out to be not entirely
baseless, at least when applied to societies shaped by specific
evolutionary pressures.

Fortunately, Cochran is on hand to drive home the real implications:

"Since it looks like there has been significant evolutionary change
over historical time, we’re going to have to rewrite every history book
ever written," said Gregory Cochran, a population geneticist at the
University of Utah. "The distribution of genes influencing relevant
psychological traits must have been different in Rome than it is
today," he added. "The past is not just another country but an entirely
different kind of people."

Wade touches upon theories of temperamental selection applied in various ethnographic instances, like with the Yanomamo,  whose wafaring reputation may have an evolutionary basis (Yanomamo men who kill in battle have three times more offspring than men who do not). And he devotes careful consideration to the case of Ashkenazi Jews, whose conspicuously high intelligence and predisposition toward certain diseases has provoked some of the most fascinating speculation about the power of Darwinism to shape human nature, even on the cusp of modernity:

The most recent example of a society’s possible genetic response to
its circumstances is one advanced by Dr. Cochran and Henry Harpending,
an anthropologist at the University of Utah. In an article last year
they argued that the unusual pattern of genetic diseases found among
Ashkenazi Jews (those of Central and Eastern Europe) was a response to
the demands for increased intelligence imposed when Jews were largely
confined to the intellectually demanding professions of money lending
and tax farming. Though this period lasted only from 900 A.D. to about
1700, it was long enough, the two scientists argue, for natural
selection to favor any variant gene that enhanced cognitive ability.

One
theme in their argument is that the variant genes perform related
roles, which is unlikely to happen by chance since mutations hit the
genome randomly. A set of related mutations is often the mark of an
evolutionary quick fix against some sudden threat, like malaria. But
the variant genes common among the Ashkenazi do not protect against any
known disease. In the Cochran and Harpending thesis, the genes were a
response to the demanding social niche into which Ashkenazi Jews were
forced and the nimbleness required to be useful to their unpredictable
hosts.

900 to 1700 A.D.  That’s like yesterday, man.  Is it coming into focus, now? I thought so.  Better not tell your friends in that Jared Diamond book club.