DURHAM, N.C. -- Duke University Medical Center anthropologists have offered anatomical evidence from skulls suggesting that human vocal abilities may have appeared much earlier in time than is suggested by the first archaeological evidence for speech.
The scientists measured the pencil-sized "hypoglossal canal" -- which carries the motor nerve controlling the tongue -- in the skulls of humans, apes and fossil hominids. They found that the canal in Neanderthals and early humans more closely matched that of modern humans than did the smaller canals of apes and proto-humans such as Australopithecus.
The scientists, Professors of Biological Anthropology and Anatomy Richard Kay and Matt Cartmill, and student Michelle Balow, published their findings in the April 28 Proceedings of the National Academy of Sciences.
In their studies, the scientists made rubber casts of the hypoglossal canals in skulls of chimpanzees, gorillas and humans, as well as those of three specimens of the early "man-ape" Australopithecus, two archaic members of the genus Homo, two Neanderthals and one early Homo sapiens.
"Our conjecture is that the size of this canal reflects the fineness of
the motor control over the tongue in people," Cartmill said. "People don't need
a big nerve to the tongue so they can eat; people don't process their food any
better than apes do. And that's what the tongue is mainly for in most mammals:
for the stereotyped behavior of manipulating food to position it for chewing."
Contact: Dennis Meredith