February 8, 2012
Genetic Mixing, Not Extinction, Led To Neanderthals’ Demise
Rather than being physically wiped out, a new study suggests that Neanderthals were likely integrated into the gene pool of early humans after the two groups crossed paths and began interbreeding.
The new study, published in the journal Advances in Complex Systems (ACS), was written by C. Michael Barton of Arizona State University (ASU) and Julien Riel-Salvatore of the University of Colorado Denver, and "builds on work published last year in the journal Human Ecology and on recent genetic studies that show a Neanderthal contribution to the modern human genome," according to a February 6 ASU press release.Barton and Riel-Salvatore used archaeological data in order to track behavioral, cultural, and social-ecological changes throughout Western Eurasia over a span of 120,000 years.
Their computer models showed both Neanderthals and early humans began to interact and mate more as a result of shifting land-use patterns during the Upper Pleistocene era, resulting in a hybridization of the two species rather than the out-and-out extinction of either.
While Neanderthals were limited to the western part of the supercontinent, and as the smaller population were the ones to effectively die-out, the researchers found that "succeeding hybrid populations still carry genes from the regional group that disappeared," according to the press release.
Thus, while some anthropologists believe that the species was completely wiped out, Barton and Riel-Salvatore argue that their DNA actually entered the human gene pool sometime around the last ice age.
This genetic mixing would likely have occurred despite possible social barriers blocking mating between the two species, and would likely have been influenced by "cultural and climatic forces," university officials said.
"The traditional story in textbooks doesn't fit well with what we know about hunter-gatherers. For the most part, they don't like to go far from home. It's dangerous," Barton said in a statement Monday, adding that both cultural and biological influences are equally important contributing factors in the course of human evolution.
Riel-Salvatore called it one of the first attempts to "explicitly address the impact of various degrees of social avoidance on possible hybridization between the two groups.
"Recent sequencing of ancient Neanderthal DNA indicates that Neanderthal genes make up from 1 to 4 percent of the genome of modern populations -- especially those of European descent," he added. "While they disappeared as a distinctive form of humanity, they live on in our genes. What we do in this study is propose one model of how this could have happened and show that behavioral decisions were probably instrumental in this process."
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