Chance, not natural selection, behind human evolution?

March 20th, 2008 - 3:01 pm ICT by admin  


New York, March 20 (IANS) Chance, not natural selection, best explains why the skulls of humans and ancient Neanderthals evolved differently, contends a new study that may alter perceptions about evolution. Researchers at the University of California at Davis used sophisticated mathematical models to crunch fossil data from earlier studies to conclude that Neanderthals and modern humans split about 370,000 years ago.

This is very close to the estimate by other researchers who have dated the split based on DNA sequences from ancient Neanderthal and modern-day humans, Sciencedaily reported.

The proximity of the two estimates - one based on studying bones and the other on genes - is significant, says anthropologist Tim Weaver, who led the team.

“(The) message may be that we should reconsider the idea that all (physical) changes are due to natural selection, and instead consider that some of them may be due to genetic drift,” Weaver said.

“This may have interesting implications for our understanding of human evolution.”

Findings of the study have been published in the latest issue of the Proceedings of the National Academy of Sciences.

The latest study builds on findings from a study Weaver published last year in the Journal of Human Evolution, in which the team compared cranial measurements of 2,524 modern human skulls and 20 Neanderthal specimens.

The researchers had then concluded that random genetic change, or genetic drift, most likely account for the cranial differences.

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