by Playfuls Staff |
4th December 2006
Scientists in Germany hope to construct a complete blueprint of the Neanderthal genetic code within two years, a step which could one day lead to enabling our long-lost prehistoric [more] cousins to populate the earth again.
The irony is not lost on scientists, many of whom believe it was our own species which killed off the Neanderthals 30,000 years ago. Now, thanks to us, Neanderthals may live again.
A significant first step towards sequencing the Neanderthal genome has already been taken by two teams investigating the same 38,000- year-old fossil bones from Croatia.
Their results provide the most thorough comparison yet of modern human and Neanderthal DNA.
They show Homo sapiens and Homo neanderthalensis went their separate evolutionary ways between 400,000 and 500,000 years ago - and showed no sign of wanting to get back together again by interbreeding.
Although close cousins, they belong to different branches of the human evolutionary tree.
Neanderthals lived in Europe and Asia long before the arrival of our ancestors from Africa.
The two are thought to have co-existed for around 10,000 years before Neanderthals became extinct around 30,000 years ago.
Many experts believe they were unable to compete with the more innovative and adaptable Homo sapiens for food, clothing and shelter. Others suspect that our ancestors systematically killed them off or else encroached on their habitat with disastrous results for them -- as has happened so often in human history.
Fossil remains show that Neanderthals looked different from us, had projecting faces, heavy brow ridges, and low foreheads, and lacked chins. They were also much more robustly built than modern humans.
There has been much speculation over the possibility that Neanderthals and early modern humans interbred.
Genetic research makes it appear unlikely, but some experts have pointed to fossil finds suggesting that interbreeding might have occurred. The skeleton of a child unearthed in Portugal seemed to share both Neanderthal and modern human features, although the evidence was inconclusive.
The new studies support those who believe there was no large-scale interbreeding between our ancestors and Neanderthals, but do not rule out the possibility altogether.
Dr Svante Paabo, from the Max Planck Institute in Leipzig, Germany, who was a member of both research teams, said: "While unable to definitively conclude that interbreeding between the two species of humans did not occur, analysis of the nuclear DNA from the Neanderthal suggests the low likelihood of it having occurred at any appreciable level."
The DNA was extracted from fossil bones discovered in Vindija Cave in Croatia in 1980.
Two different DNA sequencing techniques were employed by the Nature and Science teams.
The first group covered the largest amount of ground, working out the sequences of about a million letters of genetic code from the total three billion that make up the Neanderthal genome. One group of researchers sequenced just over 65,000, but focused more closely on similarities with human genes, the strands of DNA that make proteins.
Sequencing ancient Neanderthal DNA is a hugely difficult task given the degree to which it is fragmented and contaminated by other genetic material.
Another team, led by Dr Paabo, said it is now ready to press ahead with plans to sequence the entire Neanderthal "book of life."
Technical improvements are on the way that would make the retrieval of DNA sequences 10 times more efficient, he pointed out.
He said: "In view of that prospect, we have recently initiated a project that aims at achieving an initial draft version of the Neanderthal genome within two years."
Unravelling the Neanderthal genome will lead to a greater understanding of the way intelligent humans evolved.
By Ernest Gill, Dpa© 2006 DPA
