"This enabled us to calculate for the first time when in pre-history Homo sapiens and Homo neanderthalensis coalesced to a single genome," Rubin said.
Comparative genomics in this study indicated that the common genetic ancestor of Neanderthal and modern humans lived about 706,000 years ago. The ancestors of all humans and Neanderthals split into two separate species some 330,000 years later. Rubin and his colleagues were also able to shed new light on the long-standing question of whether Neanderthals and humans mated during the thousands of years the two species cohabitated parts of Europe. Some scientists have suggested that rather than die out, Neanderthals as a species were bred out of existence by the overwhelming populations of Homo sapiens.
Said Rubin, "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."
With their metagenomic library-based approach to genome sequencing and analysis, Rubin and Noonan believe that in the future, scientists will be able to study specific sequences within the Neanderthal genome to determine the genetic changes that distinguished modern humans from our Neanderthal cousins. Among other advantages, this might help answer the most persistent mystery of all: Why did Neanderthals become extinct?
In addition, said Rubin, "Reaching into the Neanderthal genome library will facilitate future sequence-based scientific explorations of Neanderthal biological features, features that could never be explored based on the few bones and associated stone artifacts that are left for anthropologists to identify."
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Contact: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
15-Nov-2006