PNAS:现代人与尼安德特人30万年前分化
科学家们称，仅仅观察头骨的大小就可以得出结论，现代人类和尼安特人是在30万年前分化为两支的。
相关论文3月17日在线发表于美国《国家科学院院刊》（PNAS）上。（来源：EurekAlert!中文版）
生物谷推荐原始出处：
（PNAS），doi：10.1073/pnas.0709079105，Timothy D. Weaver，Chris B. Stringer
Close correspondence between quantitative- and molecular-genetic divergence times for Neandertals and modern humans
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*Department of Anthropology, University of California, One Shields Avenue, Davis, CA 95616; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany; Department of Anthropology, University of Illinois at Urbana–Champaign, 109 Davenport Hall, 607 South Matthews Avenue, Urbana, IL 61801; and ¶Department of Palaeontology, Natural History Museum, London SW7 5BD, United Kingdom
Edited by Erik Trinkaus, Washington University, St. Louis, MO, and approved January 17, 2008 (received for review September 27, 2007)
Abstract
Recent research has shown that genetic drift may have produced many cranial differences between Neandertals and modern humans. If this is the case, then it should be possible to estimate population genetic parameters from Neandertal and modern human cranial measurements in a manner analogous to how estimates are made from DNA sequences. Building on previous work in evolutionary quantitative genetics and on microsatellites, we present a divergence time estimator for neutrally evolving morphological measurements. We then apply this estimator to 37 standard cranial measurements collected on 2,524 modern humans from 30 globally distributed populations and 20 Neandertal specimens. We calculate that the lineages leading to Neandertals and modern humans split 
311,000 (95% C.I.: 182,000 to 466,000) or 435,000 (95% C.I.: 308,000 to 592,000) years ago, depending on assumptions about changes in within-population variation. These dates are quite similar to those recently derived from ancient Neandertal and extant human DNA sequences. Close correspondence between cranial and DNA-sequence results implies that both datasets largely, although not necessarily exclusively, reflect neutral divergence, causing them to track population history or phylogeny rather than the action of diversifying natural selection. The cranial dataset covers only aspects of cranial anatomy that can be readily quantified with standard osteometric tools, so future research will be needed to determine whether these results are representative. Nonetheless, for the measurements we consider here, we find no conflict between molecules and morphology.
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