Scientists Say Differences Between “Neanderthal” and “Moderns” Not Due to Natural Selection

Posted by Chris Parker
Mar 20 2008

Science continues to wrestle with its own creation; the primitive cave man. There was no such thing, of course. (There were people who lived in caves). Once more, a reminder that science has already determined that “Neanderthal” and “Modern man” are genetically identical; ie each man’s DNA is 99.99% the same as any other man’s. 

Culture, Not Skulls, Gave Humans Edge Over Neanderthals
By Clara Moskowitz, LiveScience Staff Writer
posted: 2008-03-17

The first modern humans had something Neanderthals didn’t. About 30,000 years ago, our Neanderthal neighbors died off while we survived. Scientists are unsure what gave us an edge, but new research could help narrow down the possibilities.

A team of anthropologists has compared measurements of Neanderthal skulls to modern human skulls, and argues that most variations among them are the result of random changes that occur over time, and not of adaptations driven by natural selection.

“We’re actually saying that the differences between modern humans’ skulls and Neanderthals’ are not due to changes that increased people’s ability to survive and reproduce,” said researcher Tim Weaver, an anthropologist at the University of California, Davis. “Whatever advantages humans had over Neanderthals didn’t have to do with the size and shape of the cranium.”

In other words, modern humans don’t seem to have developed skeletal adaptations that gave them better eyesight, hearing or smell than Neanderthals.

Dating the divergence

The skull analysis allowed the researchers to calculate that Neanderthals and modern humans last shared a common ancestor about 370,000 years ago. This estimate closely matches the time frame for human-Neanderthal divergence previous researchers calculated using DNA-dating methods. Weaver and his colleagues calculated the date using a model that assumed none of the differences in skull shape affected survival and reproduction. Their system attributed any variations to chance mutations, not functional adaptations. The fact that their findings agree with the previous calculation based on DNA-dating supports the researchers’ assumption, Weaver said.

“It was a check to see if this model was correct,” Weaver told LiveScience. “If we had gotten a different estimate, then it might mean that the differences were more based on natural selection. We used this as evidence in support of the idea that most of the differences were due to chance and not functional adaptations.”

A counterintuitive hypothesis

This finding may contradict a common belief that humans won out over Neanderthals because they acquired helpful physical changes in their skulls. “Most researchers over the past 150 years, since we’ve known about Neanderthals, have thought that the differences between their skulls and our skulls were due to natural selection,” Weaver said. “On the surface it sounds counterintuitive that in a cranium that’s performing all these vital functions, the differences are due to chance.” Erik Trinkaus, an anthropologist at Washington University in St. Louis who did not work on the study, said the research cannot establish absolutely that natural selection did not create skull differences between Neanderthals and modern humans, or even that the divergence date of 370,000 years is accurate, because both dating methods are only looking at chance mutations.

“I think the main thing their paper contributes is it shows that when you look at a series of anatomical characteristics that are likely to be neutral, they paint the same kind of evolutionary picture as molecular genetic data,” Trinkaus said.

The Balance of this article can be found here…

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