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genetic evidence reich

genetic evidence reich - FOCUS | | GENETICS E J anuary 2 3...

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January 23, 2009 Back Issues Contact Us Keyword Search Calendar Infectious Diseases Topical Treatment Quashes Herpes with RNAi Leadership Frenk Voices Goals for School Of Public Health Genetics Early Males on the Move Cell Biology Dual-purpose Mechanism Activates Protein, Drives Cell Motility Drug Policy Generics Meeting Frames History of Cheaper, Unbranded Drugs Research Briefs Cone Death in Retina Traced to Lack of Nutrition Consortium Is Mapping Immune Cell Function Bulletin HMS Dean Convenes Committee to Review Conflicts of Interest Educator-researcher Will Lead HMS Academy Dohlman Chair Begins with Scientific Vision Awards Offered for Clinical Systems Innovation GENETICS Early Males on the Move X Chromosome Points to Mostly Male Migrants in Dispersal out of Africa Somewhere in Africa, between 60,000 and 100,000 years ago, a small population of humans got it into their newly rounded skulls to set out across the continent and take up residence in the northeast corner, possibly in the Nile Valley. According to this scenario, popularly known as the out-of-Africa hypothesis, members of this founding population swept north into the Middle East and Europe, east into Asia, and south into Australia, replacing the Neanderthals and other hominids. Graham Ramsay The population of early humans that migrated from Africa to Europe and Asia was fed by waves of men, according to a new study by Alon Keinan (right), David Reich, and colleagues. But the initial urge to move—the founding impulse—may have been one that occurred primarily among the males of the species. A new study by Alon Keinan, David Reich , and colleagues in the January issue of Nature Genetics suggests that the original out-of-Africa population included significantly more males than females and might have been fed by successive waves of mostly male migrants. Genetic Footprints The researchers came to this proposal by comparing the amount of genetic drift occurring on the X and other chromosomes of three different groups of modern humans. First described in the 1920s by the great geneticist Sewall Wright, genetic drift occurs when variants change in frequency not by natural selection but instead by chance, through the shuffling of genes during meiosis or other random events associated with reproduction.
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