Friday, July 28, 2006

Good Luck

Scientists Hope to Unravel Neanderthal DNA

July 21, 2006
By NICHOLAS WADE
NYTimes

Researchers in Germany said Thursday that they planned to collaborate with an American company in an effort to reconstruct the genome of Neanderthals, the archaic human species that occupied Europe from 300,000 years ago to 30,000 years ago, until being displaced by modern humans.

Long a forlorn hope, the sequencing, or decoding, of Neanderthal DNA suddenly seems possible because of a combination of analytic work on ancient DNA by Svante Paabo, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a new method of DNA sequencing developed by a Connecticut company, 454 Life Sciences.

The initial genome to be decoded comes from 45,000-year-old Neanderthal bones found in Croatia, though bones from other sites may be analyzed later. Because the genome must be kept in constant repair and starts to break up immediately after the death of the cell, the material surviving in Neanderthal bones exists in tiny fragments 100 or so DNA units in length. As it happens, this is just the length that works best with the 454 machine, which is also able to decode vast amounts of DNA at low cost.

Recovery of the Neanderthal genome, in whole or in part, would be invaluable for reconstructing many events in human prehistory and evolution. It would help address such questions as whether Neanderthals and humans interbred, whether the archaic humans had an articulate form of language, how the Neanderthal brain was constructed, if they had light or dark skin, and the total size of the Neanderthal population. [...]

95 percent of [DNA found] in the Neanderthal bones belongs to ancient bacteria, said Michael Egholm, a vice president of 454 Life Sciences. But bacterial sequences can be recognized and discarded, he said.

Because Neanderthal DNA is so scarce, Dr. Paabo and the 454 Life Science researchers developed their methods on ancient DNA from cave bears and mammoth. [...]

The first goal of the project will be to sequence three billion units of Neanderthal DNA, corresponding to the full length of the Neanderthal genome. This will require decoding 20 times as much DNA, because so much of the DNA in the Neanderthal bones belongs to bacteria.

Genomes usually must be decoded several times over to get a complete and accurate sequence, but the first three billion bases of Neanderthal should “hit all the essential differences,” Dr. Egholm said. [...]

One of the most important results that researchers are hoping for is to discover, from a three-way comparison of chimp, human and Neanderthal DNA, which genes have made humans human. The chimp and human genomes differ at just 1 percent of the sites on their DNA. At this 1 percent, Neanderthals resemble humans at 96 percent of the sites, to judge from the preliminary work, and chimps at 4 percent. Analysis of these DNA sites, at which humans differ from the two other species, will help understand the evolution of specifically human traits “and perhaps even aspects of cognitive function,” Dr. Paabo said.

The degree of resemblance between humans and Neanderthals is fiercely debated by archaeologists, and even issues like whether Neanderthals had language have not been resolved. Dr. Paabo believes that genetic analysis is the best hope of doing so. He has paid particular attention to a gene known as FOXP2, which from its mutated forms in people seems to be involved in several advanced aspects of language.

A longstanding dispute among archaeologists is whether the modern humans who first entered Europe 45,000 years ago, ultimately from Africa, interbred with the Neanderthals or forced them into extinction. [...]
Evidence from the human genome suggests some interbreeding with an archaic species, [says Bruce Lahn, a geneticist at the University of Chicago], which could have been Neanderthals or other early humans. [...]

Dr. Stephen O’Brien, a geneticist at the National Cancer Institute, said that having the Neanderthal genome would be “a very exciting prospect” because it would serve as a reference point for deciding which genes had been selected for in recent human evolution.

The chimpanzee, with which humans shared an ancestor who lived some five million years ago, is one such reference point but the Neanderthals, who split from the modern human lineage some 500,000 years ago, would provide a much more helpful signpost to recent evolutionary events, Dr. O’Brien said, like adaptations as modern humans dispersed from their African homeland and the genetic differences between the three major human ethnic groups of Africans, Asians and Europeans. [...]

If Dr. Paabo and 454 Life Sciences should succeed in reconstructing the entire Neanderthal genome, it might in theory be possible to bring the species back from extinction by inserting the Neanderthal genome into a human egg and having volunteers bear Neanderthal infants. This might be the best possible way of finding out what each Neanderthal gene does, but there would be daunting ethical problems in bringing a Neanderthal child into the world again.

Dr. Paabo said that he could not even imagine how such a project could be accomplished and that in any case ethical concerns “would totally preclude such an experiment.”

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I'm quite curious about what happened to the Neanderthals. Hopefully it was a "make love, not war" scenario, but based on human history, I don't think that that's likely.

3 Comments:

Blogger Bret said...

"...there would be daunting ethical problems in bringing a Neanderthal child into the world again."

Nah. If we can put chimpanzees in zoos, why not breed a colony of neanderthal's for zoos too?

July 28, 2006 4:00 PM  
Blogger Harry Eagar said...

Free Asiago Cheese!

No peace until Asiago Cheese is released!

Down with oppressors of Asiago Cheese!

July 28, 2006 7:39 PM  
Blogger Oroborous said...

I'm afraid that I cannot join your rally against the oppressors, as I'm an Asiago cheese exploiter myself.

Bret:

Yeah, I had the same thought - why not bring some Neanderthals into the world ?

If they are very much like us, they can be integrated into modern society, and if they are not like us, we can establish a colony and preserve for them in Costa Rica or Papua New Guinea, or somesuch.

But obviously, we can't just have one or two, if we bring them back we have to have at least several dozen of them, for companionship.

July 28, 2006 10:41 PM  

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