Post by Charlie Bass on Mar 28, 2004 13:16:34 GMT -5
Ancient DNA, late Neandertal survival, and modern human and Neandertal admixture
Timothy D. Weaver Postdoctoral Fellow, Department of Zoology, University of Wisconsin Madison, 430
Lincoln Drive, Madison, WI 53706 USA
Charles C. Roseman Doctoral Candidate, Department of Anthropological Sciences, Stanford University, 450
Serra Mall, Building 360, Stanford, CA 94305 2117 USA
One of the longest standing questions in paleoanthropology is the place of Neandertals in human evolution. Most researchers now favor a predominately extra European origin for the earliest modern human successors of Neandertals in Europe. Debate today centers on the degree to which modern humans and Neandertals interbred. Analyses of mitochondrial (mt) DNA extracted from multiple Neandertal fossils have confirmed abundant skeletal evidence that Neandertals were distinct relative to recent humans. The distinctiveness of Neandertal mtDNA also shows that either modern humans and Neandertals diverged deep in the past or that human mtDNA diversity was much greater in the past. However, Neandertal mtDNA may tell us little about admixture between modern humans and Neandertals, because Neandertal lineages could have been lost in living humans through random genetic drift. What is not often recognized is that any calculated probability that Neandertal mtDNA lineages would have been lost depends heavily on demographic history and how this history is modeled.
In this study, we examine the likelihood that there could have been both substantial admixture between modern humans and Neandertals and the complete loss of Neandertal mtDNA lineages in living humans by simulating demographic models derived from several models of modern human origins currently being discussed in the paleoanthropological literature. Our preliminary results suggest that for some demographic models derived from archaeological and other genetic evidence, it is unlikely that Neandertals contributed substantially to the modern human gene pool. One model that may allow for both substantial admixture between modern humans and Neandertals and the loss of Neandertal mtDNA lineages is a diffusion wave, but this model does not appear to fit the archaeological record of Europe. Our results stress the importance of fully integrating archaeological, fossil, and genetic evidence in investigations of modern human origins.
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Timothy D. Weaver Postdoctoral Fellow, Department of Zoology, University of Wisconsin Madison, 430
Lincoln Drive, Madison, WI 53706 USA
Charles C. Roseman Doctoral Candidate, Department of Anthropological Sciences, Stanford University, 450
Serra Mall, Building 360, Stanford, CA 94305 2117 USA
One of the longest standing questions in paleoanthropology is the place of Neandertals in human evolution. Most researchers now favor a predominately extra European origin for the earliest modern human successors of Neandertals in Europe. Debate today centers on the degree to which modern humans and Neandertals interbred. Analyses of mitochondrial (mt) DNA extracted from multiple Neandertal fossils have confirmed abundant skeletal evidence that Neandertals were distinct relative to recent humans. The distinctiveness of Neandertal mtDNA also shows that either modern humans and Neandertals diverged deep in the past or that human mtDNA diversity was much greater in the past. However, Neandertal mtDNA may tell us little about admixture between modern humans and Neandertals, because Neandertal lineages could have been lost in living humans through random genetic drift. What is not often recognized is that any calculated probability that Neandertal mtDNA lineages would have been lost depends heavily on demographic history and how this history is modeled.
In this study, we examine the likelihood that there could have been both substantial admixture between modern humans and Neandertals and the complete loss of Neandertal mtDNA lineages in living humans by simulating demographic models derived from several models of modern human origins currently being discussed in the paleoanthropological literature. Our preliminary results suggest that for some demographic models derived from archaeological and other genetic evidence, it is unlikely that Neandertals contributed substantially to the modern human gene pool. One model that may allow for both substantial admixture between modern humans and Neandertals and the loss of Neandertal mtDNA lineages is a diffusion wave, but this model does not appear to fit the archaeological record of Europe. Our results stress the importance of fully integrating archaeological, fossil, and genetic evidence in investigations of modern human origins.
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