Neanderthals, Humans Share Language Gene
MICHELE NORRIS, host:
Somewhere deep in our DNA may lie the explanation of why humans can speak and our primate cousins cannot.
Most scientists searching for the gene or genes involved have focused on modern human DNA. But a report out today looks at a gene in Neanderthals who died more than 40,000 years ago.
NPR's Joe Palca has more.
JOE PALCA: Five years ago, geneticists made a startling discovery. By studying families with speech disorders, they found a gene called FOXP2 was crucial for language, not the only language gene but apparently one of them.
Then, when the geneticists compared the human form of FOXP2 with the same gene in chimpanzees, they found two differences, apparently important differences. And what's more, the geneticists calculated these differences appeared fairly recently in evolutionary terms between a hundred and two hundred thousand years ago. That would make it a very modern development, something that even our close cousins, the Neanderthals, wouldn't have.
Dr. JOHANNES KRAUSE (Geneticist, Max Planck Institute for Evolutionary Anthropology): Since we assumed that the Neanderthals and modern humans diverged around 500,000 years ago.
PALCA: Johannes Krause is a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig. His specialty is studying ancient DNA. And he thought that could confirm that Neanderthals were missing the modern gene for language by looking directly at DNA extracted from Neanderthal bones.
Now, one of the things that make studying ancient DNA tricky is you want to be sure it hasn't been contaminated by modern DNA. Just touching an ancient bone fragment can leave a trace of modern genetic material. So Krause has set up a collaboration with Spanish anthropologist who had just come across a new deposit of Neanderthal bones. The Spanish team went to extraordinary lengths to avoid contaminating their bone samples.
Dr. KRAUSE: They just put them in the freezer and sent them off to (unintelligible), take them out of the sediments here in our clean room. That really makes it unique and also really special because we have very little contamination, very good preservation and we get the bones really fresh from the site.
PALCA: Soon, Krause and his colleagues had enough Neanderthal DNA to work with. They looked at the FOXP2 gene, expecting that the two key changes for language wouldn't be there.
Dr. KRAUSE: When we then looked at the supposition of the Neanderthals, we found them to be the same like in modern humans. We were really, really surprised.
PALCA: That means that those changes must have appeared far earlier than the original researchers had estimated - at least 500,000 years ago or more. The new results appear in the journal Current Biology.
But anthropologist Erik Trinkaus of Washington University in Saint Louis says Krause shouldn't have been surprised.
Dr. ERIK TRINKAUS (Anthropologist, Washington University): It certainly didn't fit with the abundance of evidence that we have, particularly, from the archeological record that indicates that language and complex human social behavior suddenly appeared 100,000 years ago.
PALCA: Trinkaus says the new study points up a serious problem with making predictions about when a gene appeared in the course of human evolution if you're only comparing DNA from modern humans with chimpanzees.
Dr. TRINKAUS: In order to do that you have to make a whole series of assumptions, some biological, some mathematical, and this is the first case I know of. Well, one of these has actually been tested using ancient DNA. And it shows very clearly that the extrapolations back from modern variation are not very accurate. In this case, they're simply wrong.
PALCA: Trinkaus says finding the modern human form of FOXP2 and Neanderthals may help remind people that our cavemen cousins may not have been so different from us after all.
Joe Palca, NPR News, Washington.