While scientists agree speech is probably the most important behavioral attribute distinguishing human beings from other animals, they have been at a loss to determine when and how that transforming evolutionary step occurred.
All they had been able to agree on is that the earliest clear evidence for human speech is found in cave art and other artifacts, particularly in Europe and Africa, that began appearing 40,000 years ago.
Now scientists at Duke University have explored a new avenue of fossil anatomy and found surprising evidence suggesting vocal capabilities such as those of modern humans may have evolved among species of the Homo line more than 400,000 years ago. By then, their research shows, human ancestors may have had a full modern complement of the nerves leading to the muscles of the tongue and so could have been capable of forming speech sounds.
The new findings, moreover, indicate the Neanderthals, relatives of modern humans, could have had the same gift for speech. Their extinction about 30,000 years ago often has been attributed in part to speech deficiencies, restricting their ability for cultural innovation.
In a report being published today in The Proceedings of the National Academy of Sciences, the Duke anthropologists say that if their interpretation of the tongue nerves is correct, "then humanlike speech capabilities may have evolved much earlier than has been inferred from the archaeological evidence for the antiquity of symbolic thought."
The research was conducted by Dr. Richard Kay and Dr. Matt Cartmill at Duke Medical Center in Durham, N.C., with the assistance of a former student, Michelle Balow. The results also were described earlier this month in Salt Lake City at a meeting of the American Association of Physical Anthropology.
"This is evidence for the proposition that Neanderthals could talk," Cartmill said Sunday. "Did they sound like modern humans? I don't know."
Anthropologists familiar with the research said the findings were interesting and exciting. Some were reserving judgment, but not Dr. Erik Trinkaus, an anthropologist at Washington University in St. Louis, who specializes in Neanderthal studies.
"I think it's not only a reasonable conclusion," he said, "but one long overdue."