Templeton_2007

Templeton_2007 - PERSPECTIVE...

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PERSPECTIVE doi:10.1111/j.1558-5646.2007.00164.x GENETICS AND RECENT HUMAN EVOLUTION Alan R. Templeton Department of Biology, Campus Box 1137, Washington University, St. Louis, Missouri 63130 E-mail: temple a@wustl.edu Received January 12, 2007 Accepted April 19, 2007 Starting with “mitochondrial Eve” in 1987, genetics has played an increasingly important role in studies of the last two million years of human evolution. It initially appeared that genetic data resolved the basic models of recent human evolution in favor of the “out-of-Africa replacement” hypothesis in which anatomically modern humans evolved in Africa about 150,000 years ago, started to spread throughout the world about 100,000 years ago, and subsequently drove to complete genetic extinction (replacement) all other human populations in Eurasia. Unfortunately, many of the genetic studies on recent human evolution have suffered from scientific flaws, including misrepresenting the models of recent human evolution, focusing upon hypothesis compatibility rather than hypothesis testing, committing the ecological fallacy, and failing to consider a broader array of alternative hypotheses. Once these flaws are corrected, there is actually little genetic support for the out-of-Africa replacement hypothesis. Indeed, when genetic data are used in a hypothesis-testing framework, the out-of-Africa replacement hypothesis is strongly rejected. The model of recent human evolution that emerges from a statistical hypothesis-testing framework does not correspond to any of the traditional models of human evolution, but it is compatible with fossil and archaeological data. These studies also reveal that any one gene or DNA region captures only a small part of human evolutionary history, so multilocus studies are essential. As more and more loci became available, genetics will undoubtedly offer additional insights and resolutions of human evolution. KEY WORDS: Human evolution, mitochondrial Eve, multiregional model, nested clade analysis, out-of-Africa replacement, phylo- geography. With the publication of a paper entitled “Mitochondrial DNA and human evolution” by Cann et al. in 1987, genetics has played an increasingly important role in our understanding of human evolu- tion over the last two million years. Cann et al. (1987) presented a genetic survey based on restriction site polymorphisms in 147 human mitochondrial DNA samples whose maternal origins came from five different geographical regions that spanned the globe. They estimated the tree of the resulting 133 mitochondrial haplo- types using maximum parsimony, although incorrectly (Maddison 1991). Subsequent data and analyses showed that despite their er- rors, two basic inferences were correct: (1) the mitochondrial tree was rooted in Africa, and (2) all the branches were relatively short, implying a recent common mitochondrial ancestor (dubbed “Eve” in popular accounts). From these observations, Cann et al. con- cluded that their data supported a model of human evolution in
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This note was uploaded on 11/25/2009 for the course BI 379 taught by Professor Kavaler during the Spring '09 term at Colby.

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Templeton_2007 - PERSPECTIVE...

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