A team of researchers led by the University of Tübingen's Professor Katerina Harvati has shown that anatomically modern humans spread from Africa to Asia and Europe in several migratory movements. The first ancestors of today's non-African peoples probably took a southern route through the Arabian Peninsula as early as 130,000 years ago, the researchers found. The study is published by Professor Katerina Harvati and her team from the Institute for Archaeological Sciences at the University of Tübingen and the Senckenberg Center for Human Evolution and Palaeoenvironment, in collaboration with colleagues from the University of Ferrara, Italy, and the National Museum of Natural History, France. The study appears in the online Early Edition of the Proceedings of the National Academy of Sciences.
The scientists tested different hypothetical dispersal scenarios, taking into account the geography of potential migration routes, genetic data and cranial comparisons. They found that the first wave of migration out of Africa started earlier than previously thought, taking place as early as the late Middle Pleistocene -- with a second dispersal to northern Eurasia following about 50,000 years ago.
Most scientists agree that all humans living today are descended from a common ancestor population which existed 100,000 to 200,000 years ago in Africa. The decreasing genetic and phenotypic diversity observed in humans at increasing distances from Sub-Saharan Africa has often been interpreted as evidence of a single dispersal 50,000 to 75,000 years ago. However, recent genetic, archaeological and palaeoanthropological studies challenge this scenario.
Professor Harvati's team tested the competing out-of-Africa models of a single dispersal against multiple dispersals of anatomically modern humans. The scientists compared modern human crania from different parts of the world, neutral genetic data, and geographical distances associated with different dispersal routes. Likewise, they reconstructed population split times from both the genetic data and as predicted by each competing model. Because each dispersal scenario is associated with specific geographic and temporal predictions, the researchers were able to test them against the observed neutral biological distances between groups, as revealed from both genetic and cranial data.
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