Sunday, March 8, 2009

Neanderthal Genome

As of now, the sequencing of the "Neanderthal" genome is a little over 60% complete - based upon less than a handfull of genetic samples. One hundred years from now, we'll realize that the "Neanderthals" and the "humans" were/are the same - our technology is fast catching up, once we can get past our 19th century prejudices. There are enough hints in that direction, if only some scientist would be brave enough to connect the dots! At times it seems that Svante Pääbo hints at this... From "The Science Show", February 28, 2009 DNA from Neanderthals listen now download audio Sites in Croatia and Spain have revealed DNA sequences of Neanderthals. They are 38,000 years old. Other sites are in Germany and southern Russia. These date back 70,000 years. New techniques allow sequences to be prepared from less than one gram of material. Random fragments are sequenced and mapped to the human genome. Some known genetic variants are in common with people of today. These reveal features such as lactose tolerance. Neanderthals were not tolerant to lactose. ... Robyn Williams: So who is your closest relative? Well, don't think chimp, think German, Neanderthal, now also popping up in a few other places around Europe. Svante Pääbo of the Max Planck Institute in Leipzig has revealed two-thirds of the Neanderthal genome, an achievement you can read about in this week's Economist magazine. So where did the samples come from? Svante Pääbo: The site where the vast majority of the sequences come from is a cave called Vindija in Croatia, and the bones are around 38,000 years old. One other site which is particularly useful for us is in north western Spain, and that's a deep cave where they excavate now and find the remains of nine Neanderthals that have obviously been butchered and consumed, probably by other Neanderthals. The good thing about that site is that they excavate now, so they can remove the bone fragments under sterile conditions from the stratigraphy, freeze them in the cave and then take we get them in a frozen state directly from the excavation to the lab. The two other sites is, on the one hand, the type specimen site Neanderthal in Germany, which is particularly useful since we can then compare our results from the Croatian Neanderthal to the archetypical Neanderthal, if you like. And the other site is in southern Russia in the Caucasus, which is quite much older than the other ones, 60,000 to 70,000 years old, so we can compare our results to really old Neanderthals. Robyn Williams: I hadn't heard before that they were cannibals. Were you surprised by that? Svante Pääbo: It actually turns out that...particularly Tim White at Berkeley has pointed this out, that the more you know what to look for in sites you see that the bodies have been de-fleshed and the bones with bone marrow in them have been crushed. There is still a discussion, is this some religious reasons for this or is it simply consumption? I think that Tim would argue that it looks like they haven't been treated much different from deer or other prey animals. (This seems to me to be rather typical "demonizing" of something we don't understand. In any event, it is well-documented that "humans" of several other much more recent civilizations engaged in cannibalism - all for religious/and or ritualistic reasons. The people who are guilty of eating dead folks purely for sustenance - how about Americans in the Donner party, heh? Sometime in the 1840's they got stranded in a wagon train up in the Rockies enroute to California, I don't have the exact date at hand. I also recall reading some years back about survivors of a plane crash eating the flesh of the dead in order to survive - I believe that was back in the 1970's. I think that crash was somewhere in South America.) . . . Robyn Williams: And you can actually test particular characteristics, like lactose intolerance, the ability to consume and digest milk. How did you do that? Svante Pääbo: When there are known genetic variants today that one knows are associated with certain features, we can then of course look if we have hit them, and in, say, 63%, sometimes we were lucky or sometimes it's even a bigger region where there are many chances for us to hit variants there. So, for example, we can look at these variants that confer lactose tolerance to adults that's typical of Europeans today, particularly the further north you go in Europe, and we can see very clearly that the Neanderthal did not carry those variants that confer the ability to drink fresh milk as an adult today. Robyn Williams: Yes, which we acquired in the last 10,000 years or so. Svante Pääbo : Yes, but of course it has been selected recently due to agriculture, but probably from some standing variant that existed before that in older times. [Suggesting an earlier common ancestor - standard operating procedure]. Robyn Williams: What did this tell you about the branching away from our ancestry? If the chimps are way back, 6.5 million years, and the Neanderthal, which might be very close to us, which lived 300,000 years ago, how close were they to us? Svante Pääbo: What you see very clearly is that they are so close to us actually genetically speaking that they do fall into our variation. So if we walk along a chromosome then in one part where it's thought I am often, say, closer to Neanderthal than what you are, and then we walk further a little bit and then you will be closer to the Neanderthal than I am. It is in a sense us drawing one of our ancestors 300,000 years ago out of the gene pool and looking at it, and there will be some Neanderthal-specific things, but from the point of view of our history it looks like looking at an ancestor of ours.

1 comment:

ALCHEssMIST said...

Thanks for the post.

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