Chance, not natural selection, best explains why the modern human skull
looks so different from that of its Neanderthal relative, according to
a new study led by Tim Weaver, assistant professor of anthropology at
"For 150 years, scientists have tried to decipher why Neanderthal
skulls are different from those of modern humans," Weaver said. "Most
accounts have emphasized natural selection and the possible adaptive
value of either Neanderthal or modern human traits. We show that
instead, random changes over the past 500,000 years or so – since
Neanderthals and modern humans became isolated from each other – are
the best explanation for these differences."
Weaver and his colleagues compared cranial measurements of 2,524
modern human skulls and 20 Neanderthal specimens, then contrasted those
results with genetic information from a separate sample of 1,056 modern
The scientists concluded that Neanderthals did not develop their
protruding mid-faces as an adaptation to icy Pleistocene weather or the
demands of using teeth as tools, and the retracted faces of modern
humans are not an adaptation for language, as some anthropologists have
Instead, random "genetic drift" is the likeliest reason for these skull differences.
Weaver conducted the research with Charles Roseman, an
anthropologist at the University of Illinois at Urbana-Champaign, and
Chris Stringer, a paleoanthropologist at the Natural History Museum in
The study appears in the August issue of the Journal of Human Evolution.
Source : University of California, Davis