Science matters
Human origins and migration Richard Harwood reports on new evidence that has led to scientists rethinking long-held beliefs 15 000
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Schematic map showing the migrations and timescales involved in the Recent African Origin model of human development
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The accumulated evidence that has tended to support the ‘Recent African Origin’ model is wide-ranging, covering skeletal analysis of geological ‘finds’ and modern genetic analysis. This evidence is summarised in accessible detail in ‘Evolution: the Human Story’ by Professor Alice Roberts (2011), while a series of TED presentations on this topic area can be found at https://www.ted.com/playlists/84/ancient_clues An interesting aspect of research into the history of human migrations is the Genographic Project initiated by National Geographic, whereby individuals can participate in such studies by contributing their DNA sample: https:// genographic.nationalgeographic.com/ However, the idea that modern people evolved in a single ‘cradle of humanity’ in East Africa some 200,000 years ago has been queried significantly by a recent report published in the journal Nature by Professor Jean-Jacques Hublin, of the Max Planck Institute (MPI) for Evolutionary Anthropology in Leipzig, Germany. Fossils of five early humans have been found in North Africa that show Homo sapiens emerged at least 100,000 years earlier than previously recognised. This report suggests that our species evolved across the whole African continent. It is claimed that the discovery and analysis of these fossils excavated at a site in Jebel Irhoud, Morocco – consisting of Autumn |
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Scientific understanding proceeds by a continuous process of the falsification of current ideas in response to experiment and the gaining of new evidence. The field of human anthropology has demonstrated this re-evaluation process spectacularly over the past 60 years or so. Some 50 years ago, no one believed that modern humans could have originated in Africa. In this period, two models of the development and emergence of Homo sapiens have been put forward by different scholars: ‘Recent African Origin’ model (or the ‘Out of Africa’ model): currently the more accepted model, with backing from genetic studies, which proposes a single area of origin for modern humans. According to this model, modern humans evolved in East Africa (the Rift Valley region) and then began to disperse throughout the world roughly 50,000 to 100,000 years ago. This single-origin hypothesis is cited as having the scientific consensus as of the mid-2000s. ‘Assimilation model’: a model involving the multiregional emergence of modern humans, a more gradual spread of modern features, and a greater level of interbreeding between different hominid lines. This model suggested a wave of Homo sapiens migrating earlier from Africa and interbreeding with local Homo erectus and Homo neanderthalensis populations in multiple regions of the globe.
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