Tuesday, December 11, 2007

Human Evolution is Accelerating

Back when I was in graduate school the general consensus was that human evolution had generally halted or at least slowed in the early Holocene. It was believed that the strong evolutionary pressures that had operated on early hunter - gatherer populations had eased with the transition to agricultural economies and settled life.

Estimable University of Wisconsin professor and anthropology blogger John Hawks is a member of a team who's research has stood this former consensus on its head. In a just published paper Hawks and his colleagues show that the rate of change in the human genome has been increasing:

"By examining more than 3 million variants of DNA in 269 people, researchers identified about 1,800 genes that have been widely adopted in relatively recent times because they offer some evolutionary benefit.

Until recently, anthropologists believed that evolutionary pressures on humans eased after the transition to a more stable agrarian lifestyle. But in the past few years, they realized the opposite was true — diseases swept through societies in which large groups lived in close quarters for a long period.

Altogether, the recent genetic changes account for 7 percent of the human genome, according to the study, published in the Proceedings of the National Academy of Sciences.

The advantage of all but about 100 of these genes remains a mystery, said University of Wisconsin at Madison anthropologist John Hawks, who led the study. But the research team was able to conclude that infectious diseases and the introduction of new foods were the primary reasons that some genes swept through populations with such speed."

RTWT as they say. Hawks has more on the paper posted at his blog.

I was also intrigued by this fact that Hawks throws out, related to the mystery of the adaptive advantage of most of these genetic changes:

"Nobody 10,000 years ago had blue eyes," Hawks said. "Why is it that blue-eyed people had a 5 percent advantage in reproducing compared to non-blue-eyed people? I have no idea."


Matt Mullenix said...

I think I'm devolving.

Chas S. Clifton said...

I have seen news summaries of this reseach, and I am confused.

Evolving how? Where on the nature/nurture issue is the leverage to be exerted.

And how would we know what color eyes people had 10,000 years ago. They were not painting portraits in the caves of Chauvin.

Is the media response just hopeful optimism:"We're going to evolve our way out of this crisis, by golly!"

Peculiar said...

Chas, you might check out John Hawks' blog: http://johnhawks.net/weblog/

He's promising an FAQ, and meanwhile has an "infrequently Asked Questions", which are probably very enlightening if you know a lot more about genetics than I. Interesting blog in any case.

Chas S. Clifton said...

I looked at the blog, and I will bookmark it.

But so much of the discussion seems like theoretical hand-waving at this point -- not that that is not necessary.

Can we yet say, for instance, that humans are more or less susceptible to Disease X? And what about those blue eyes?

I am waiting for the Executive Policymaker summary, I guess.