Thursday, July 12, 2007
Wired reports: [edited]
NA passed down through generations of mothers could help answer big questions about the human journey across continents, thanks to a massive new database created by the The Genographic Project.
The project has already yielded some provocative evidence about modern humans' interactions with Neanderthals. The DNA data shows no evidence of mutations known to be common in Neanderthals, which suggests that modern humans - at least those of European descent -- may not have mated with the long-extinct humans.
"We don't see any Neanderthal lineages in the European gene pool," said Spencer Wells, a population geneticist and director of the Genographic Project. "It would be my guess that there was no interbreeding. I can’t imagine that humans and Neanderthals didn't give it a try - maybe they formed infertile offspring. But it's speculative."
The database is the tip of the iceberg for a burgeoning field of science called genetic anthropology, which involves combining DNA data with physical evidence and histories of past civilizations. The database contains more samples than in any previous collection of its kind. As scientists study it further, they expect a detailed history of human migration in Europe will emerge.
Researchers collected mitochondrial DNA, or mtDNA, from nearly 80,000 people, who received a report on how their ancestors came to live where they live.
The scientists analyzed mutations in the samples, which came mostly from people of European descent who could afford the $100 fee (another somewhat controversial arm of the project is analyzing mtDNA mutations in indigenous people).
IBM and the National Geographic Society launched the $40 million project in 2005. The database will become publicly available Friday, and the researchers published their first results in the open-access journal PLoS Genetics.
While many scientists believe the new information will be a boon for research, others take issue with the Genographic Project's methods.
The scientists partially analyzed many mutations in nearly 80,000 samples. Instead, said Hans Bandelt of the University of Hamburg, one of the world's foremost mtDNA experts, it would have been more useful to completely sequence a smaller number of samples to get a more complete picture of mutations that have emerged since the Ice Age.
"For the time span of 15,000 to 5,000 years ago, where additional information is badly needed, the genographers can hardly offer anything useful," said Bandelt.
But Stanford University population geneticist Peter Underhill said whole mtDNA-genome sequencing is too expensive. As the project adds information about indigenous people, he added, the database will become even more powerful.
"If you couple their strategy with a breathtaking inventory of DNA samples," Underhill said, "then you've got a powerful, high-definition image of the genetic landscape."