re: First human ancestors came from Europe not Africa 7.2 million-year-old fossils indicate

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The Sahara desert as we know it today developed 2 to 3 million years ago. There is strong evidence the climate there was at the minimum semi-arid. Seeing as these fossils predate the desertification of that desert, it isn't relevant to this particular discovery.

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The movement of tectonic plates that created the Mediterranean Sea and the Alps also sparked the drying of the Sahara some 7 million years ago, according to the latest computer simulations of Earth’s ancient climate.

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Before the great desert was born, North Africa had a moister, semiarid climate. A few lines of evidence, including ancient dune deposits found in Chad, had hinted that the arid Sahara may have existed at least 7 million years ago. But without a mechanism to explain how it emerged, few scientists thought that the desert we see today could really be that old. Instead, most scientists argue that the Sahara took shape just 2 to 3 million years ago.

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Now Zhongshi Zhang of the Bjerknes Centre for Climate Research in Bergen, Norway, and colleagues have run simulations of climate change in North Africa over the last 30 million years. Their simulations take into account changes in Earth’s orbital position, atmospheric chemistry and the ratio of land to ocean as driven by tectonic forces. The models shows that precipitation in North Africa declined by more than half about 7 million years ago, causing the region to dry out.

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