Wednesday, September 05, 2007

Contamination in Neandertal DNA   posted by p-ter @ 9/05/2007 07:52:00 PM

Almost a year ago, Svante Paabo's group published an article reporting a million base pairs of DNA isolated, in principle, from Neandertal bone. The results were striking, in that Neandertals appeared much closer, genetically, to humans than one might expect. Well, Nature News has an article this week about a paper in PLoS Genetics arguing that the reason for this could actually be quite parsimonious: contamination from modern humans. From the news report:
Svante Paabo, senior author of the Nature paper, concedes that his group at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, had problems with contamination. These prompted him to change laboratory procedures and to add controls late in 2006, after the paper was published. "I agree with [Wall's] analysis," Paabo says. "Their observations are formally correct."
The paper estimates the amount of contamination at about 80%, which is pretty atrocious. The irony here, of course, is that Paabo was one of the people who made sequencing ancient DNA feasible again after fiascoes like reports of "dinosaur DNA"-- the "dinosaur" sequences ended up matching up pretty well with some of the lab members, and it appears Paabo has made the same mistake here. Fortunately, this is likely only to be a minor setback--the other group working on the DNA seems to have avoided the contamination problems, and presumably Paabo's most recent work will be more careful about it.

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