19 October 2007
Language-Gene Evolution Shared By Humans And Neanderthals
by Kate Melville
Adaptive changes in a human gene involved in speech and language processing were shared by our closest extinct relatives, the Neanderthals, suggests a study in Current Biology. The finding reveals that the human form of the gene arose much earlier than scientists had estimated previously. It also raises the possibility that Neanderthals possessed some of the prerequisites for language.
The gene in question, known as FOXP2, is the only one known to date to play a role in speech and language. People who carry an abnormal copy of the FOXP2 gene often have speech and language problems. "From the point of view of this gene, there is no reason to think that Neanderthals would not have had the ability for language," said researcher Johannes Krause, of the Max Planck Institute for Evolutionary Anthropology.
The study notes that previous analyses indicated that a very recent rise in the human FOXP2 variant had occurred as a result of strong selection, less than 200,000 years ago. "Because we know that Neanderthal and modern human populations diverged more than 300,000 years ago, we would have guessed that these changes in FOXP2 would have happened after we separated from Neanderthals," said co-researcher Svante P��bo.
The study analyzed DNA from Neanderthal fossils collected in a cave in northern Spain. They exhumed the bones under sterile conditions and froze them before transporting them to the laboratory. They then extracted DNA and sequenced the Neanderthal FOXP2 gene, revealing that it was identical to the version found in modern humans. To ensure that the Neanderthal DNA samples hadn't been contaminated with human DNA, they also sequenced parts of their Y chromosome, which was found to be distinct from that of men today.
"The current results show that the Neanderthals carried a FOXP2 protein that was identical to that of present-day humans in the only two positions that differ between human and chimpanzee," the researchers concluded. "Leaving out the unlikely scenario of gene flow [between the two lineages], this establishes that these changes were present in the common ancestor of modern humans and Neanderthals." In addition to its potential implications for the acquisition of language, the study also marks the first time a specific nuclear gene has been retrieved from Neanderthals.
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Source: Cell Press