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New insights into our origins Out of Africa above micro-CT scans of a cranium from Jebel irhoud, Africa (about 300,00 years old), and of one from Qafzeh in the
Levant (about 95,000 years old) reflect the evolutionary changes of the braincase from an elongated to a globular shape. modern features of Homo sapiens like this did not appear at the same time and place, suggesting that our species did not evolve from a single population or region in Africa.
With newly identified evidence for the earliest hominin activity outside Africa and for the diverse roots of Homo sapiens within the continent, our understanding of migration and evolution is changing. Lucia Marchini explores some of the latest thinking.
The African origin of our species Homo sapiens is widely accepted, but until recently researchers have given weight to the assumption that H. sapiens evolved from a single ancestral population or within one region in Africa. Now research into the morphology of human fossils and tools from the Middle Stone Age (a period in African prehistory between c.300,000 and 60,000-20,000 years ago) across the continent is shifting the focus away from this single origin theory, which simplifies the remarkable diversity present in the archaeological record.
Combining evidence from material culture, fossils, genetics, and the ancient climate, the new study (published in Trends in Ecology & Evolution) argues the case for multiple origins of H. sapiens from different groups across Africa that went through periods of mixing and isolation as the environment around them, whether forest or desert, changed. A range of transitional groups may have lived over a vast area of the continent stretching from Morocco to South Africa between at least 300,000 and 12,000 years ago.
Stone tools and other artefacts, with their distinct regional styles, complicate things for the single origin theory. The technological changes that mark the beginnings of the Middle Stone Age, like the move away from large hand-held cutting tools and to hafting and prepared-core technology, took place across Africa as early as 300,000 years ago at Jebel Irhoud in the north and Olorgesailie in the east, and about 280,000 years ago at Florisbad in the south. The current West African dates are younger, at about 180,000 years ago, but this area has not been the subject of as much investigation. Lead author Eleanor Scerri sums up the findings: ‘While there is a continental-wide trend towards more sophisticated material culture, this “modernisation” clearly doesn’t originate in one region or occur at one time period.’
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RIGHT As well as diversity in the fossil record, cultural diversity seen in middle Stone Age artefacts from north and south Africa points to multiple origins of H. sapiens.