Monday, April 14, 2008

Svante Paabo interview in PLoS Genetics

Svante Paabo is best known for his work with ancient DNA, including Neanderthals.

Two of the more interesting parts of the interview:

1) How to determine if there's DNA in an ancient sample:

What you actually do is a several stage process, where you first take very small samples, of say 10 mg, and just see if there are amino acids preserved—the amino acid profile of collagen. If there is no collagen preservation, it turns out there is hardly ever DNA. We can already exclude a lot of remains that way. And then we take samples of 100–200 mg, extract DNA, and see if we can find Neanderthal DNA. And then for the genome project where we need larger samples, we use bones that have very little morphological information.

So in the Museum in Zagreb, which houses the Vindija remains, we screen bones of which it cannot be said from the morphology if they are human or animal. By doing extraction from 100 mg, you can determine the species from the mitochondrial DNA. So the paleontologists gain something—they learn what species the different bones come from, and so it is easy to justify taking half a gram from them if they turn out to be Neanderthal bones.
2) and, given his interest in Egypt, he talks about this idea of looking at geography and genes along the Nile, which sounds very interesting:
But coming back to Egypt again, what I would really like to do is have a boat and sail along the Nile from the Mediterranean, where people are really “European-like” to the source of the Nile in Lake Victoria, where people are really “African-like”, and sample every 50 kilometers along this corridor through the Sahara and just see how this transition occurs. Are there sharp borders or is there a gradient? And that would be a powerful thing to look at, and it would be feasible.

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