Origins of Neanderthals: Neanderthal Genome to Unlock Secrets of Human Evolution
This research was announced on Darwin Day, 12 February 2009. The common ancestor of both Homo neanderthalis and Homo sapiens dates back some 830,000 years.
The article is from The Times, London, by Mark Henderson, Science Editor, in Chicago.
The genetic code of Neanderthal Man has been pieced together from DNA recovered from ancient fossils, providing insights into evolution that promise to reveal many of the genes that make us human.
As Homo neanderthalis is the closest evolutionary cousin of Homo sapiens that has ever existed, comparisons between its genome and those of modern humans and chimpanzees will allow scientists to identify DNA sequences that are unique to our species. Many of these will explain human capabilities that are not shared by other animals, such as complex thought, language and art.
“Studying the Neanderthals and studying the Neanderthal genome will tell us what makes modern humans really human, why we are alone, why we have these amazing capabilities,” said Jean-Jacques Hublin, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, who led the project with his colleague Professor Svante Pääbo. “It will allow us to analyse our genome and manipulate it.”
The reconstruction of the Neanderthal genome will not, however, pave the way for the resurrection of the ancient human relatives by cloning. While sufficient DNA can be recovered from fossils to allow a rough genome map to be assembled, this will be too incomplete to clone a living being, the scientists said.
“I would say that starting from DNA from a fossil, it [cloning] remains impossible,” Professor Pääbo said. “As far as I can see into the future, there isn't an improvement in technology that would make that possible.”
The announcement came on the 200th anniversary of the birth of Charles Darwin. “It is really about understanding our evolution,” Professor Pääbo said. “We will be able to catalogue the changes that happened before humans diverged from Neanderthals, and those that happened afterwards. The second goal, which is fitting for Darwin's birthday, is finding evidence of positive selection, of identifying changes that really made a difference in our ancestors.”
The Neanderthal genome, which will be presented by Professor Pääbo on Sunday at the American Association for the Advancement of Science conference in Chicago, is a first draft, containing at least some data on 63 per cent of the DNA letters that make it up. Nonetheless, it is a scientific tour de force that has greatly improved the ability to study the genetics of extinct species.
While DNA from extinct creatures has been extracted and sequenced before, this has come from animals that were frozen in permafrost, mainly mammoths, and in which soft tissue had been preserved. The Neanderthal DNA, by contrast, was taken from bones found at four sites: Vindya in Croatia, El Sidrón in Spain, Mezmaiskaya in Russia and Feldhofer in the Neander valley in Germany, where the original specimens that gave the species its name were found.
This DNA could be read because of new genome sequencing technology that has become available only in the past few years. The sequencing was conducted by 454 Life Sciences, which recently mapped the genetic code of James Watson, who with Francis Crick identified the double-helix structure of DNA.
Preliminary analysis of the Neanderthal genome has identified several critical genes that are similar or different to modern humans. Neanderthals do not appear to have the gene for lactase, which allows adults to digest milk and is common among Europeans and some Africans, but rare elsewhere in the world.
The research has also confirmed that Neanderthals share the human version of a gene called FOXP2, which is known to be involved in language, which suggests it is possible that they could have been capable of speech. “This is the only gene we happen to know about that's involved in speech, and there will be many others, so we cannot say that they could speak,” Professor Pääbo said. “However, there is no reason to assume they couldn't speak, from the little we know. How human were they? My take on that is we will probably never fully know.”
Another early finding is that Neanderthals appear not to have interbred with modern humans. “Our data show that the contribution of Neanderthals to the modern gene pool is very little, if anything,” Professor Pääbo said.
Professor Chris Stringer, head of human origins at the Natural History Museum in London, said: “If the Neanderthal genome data show little evidence of potential hybridisation, that would fit with my view from the fossil evidence that, while interbreeding was probably possible, it may have occurred only rarely, with trivial impact on modern humans.
“The populations had been separate for hundreds of thousands of years and I think there would have been significant physical and behavioural differences between them. However, larger samples would be desirable to get a more complete picture, and hopefully those will follow soon.”
The research suggests that the evolutionary split between humans and Neanderthals happened about 830,000 years ago. The Neanderthals died out around 30,000 years ago, and competition with modern humans may have been an important factor.
N.B. Origins of Neanderthal extinction, Part 1, was initiated in the group ORIGINS on 21 December 2008
and a consideration of Neanderthal Language was made in ORIGINS in September/October 2008.