Is evolution speeding up? - December 11, 2007
Evolution has accelerated in the last 40,000 years as a result of natural selection, according to a paper published this week in PNAS. Some experts are already questioning the claims however.
Using the 3.9-million HapMap SNP dataset, John Hawks, of the University of Wisconsin, Madison, and colleagues focused on so-called linkage disequilibrium. This is where genetic variations occur more often than would be predicted by chance, and where it is therefore likely that changes bring a selection advantage. Recent change is then identified by long segments of LD that have not been remodeled by DNA reshuffling (press release).
This led Hawks and co to find evidence of recent selection on about 7% of all human genes. “We are more different genetically from people living 5,000 years ago than they were different from Neanderthals,” he says.
Not that this necessarily makes us better than our great-to-the-power-n grandparents.
“Some of the mutations let us do better. We can eat simple carbohydrates, which hunter-gatherers never did. But we may also be accumulating damaging stuff,” co-author Henry Harpending of the University of Utah, told Wired.
Not everyone is convinced. Jonathan Pritchard, of the University of Chicago, told the NY Times, “My feeling is that they haven’t been cautious enough.” This sentiment has been echoed by others. There’s some interestingly technical criticism at one post on the Gene Expression blog, although another post on the same blog is more convinced.
The research paper should appear later this week.
Image: Getty