“My! What a Sloping Forehead You Have!”
Scientists in Germany and the U.S. have set off on an ambitious project to recreate the Neanderthal genome:
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.
Here’s what the scientists hope to learn:
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. Interbreeding could have been genetically advantageous to the incoming humans, says Bruce Lahn, a geneticist at the University of Chicago, because the Neanderthals were well adapted to the cold European climate — the last ice age had another 35,000 years to run — and to local diseases.
Evidence from the human genome suggests some interbreeding with an archaic species, Dr. Lahn said, which could have been Neanderthals or other early humans.
However, there’s a controversy here, and it’s enough to make the current blathering over stem cells look like an argument over “less filling” or “tastes great”:
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.”
Dr. Lahn described the idea as “certainly possible but futuristic.”
The most serious technical problem would be creating functional chromosomes from Neanderthal DNA. But ethical questions may be less surmountable. “My first consideration would be for a child born alone in the world with no relatives,” said Ronald M. Green, an ethicist at Dartmouth College. The risk would be greater if, following the plot line of Mary Shelley’s “Frankenstein,” a mate were created as a companion for the lonely Neanderthal. “This was a species we competed with,” Dr. Green said. “We would not want to recreate a situation of two competing advanced hominid species.”
But if we did manage to bring Neanderthals back, there’d be no shortage of Division I football coaches willing to be the first to break the species barrier. Could you imagine one of these guys playing linebacker for your team?