Evolution tied to Earth movement(million years ago. The earliest Homo aro...)

Tectonics movements of Earths crust, including its ever-shifting tectonic plates and the creation of mountains, valleys and ocean basins has been discussed since at least 1983 as an influence on human evolution.

But Royhan Gani says much previous discussion of how climate affected human evolution involves global climate changes, such as those caused by cyclic changes in Earths orbit around the sun, and not local and regional climate changes caused by East Africas rising landscape.

A Force from within the Earth

The geological or tectonic forces shaping Africa begin deep in the Earth, where a superplume of hot and molten rock has swelled upward for at least the past 45 million years. This superplume and its branching smaller plumes help push apart the African and Arabian tectonic plates of Earths crust, forming the Red Sea, Gulf of Aden and the Great Rift Valley that stretches from Syria to southern Africa.

As part of this process, Africa is being split apart along the East African Rift, a valley bounded by elevated shoulders a few tens of miles wide and sitting atop domes a few hundreds of miles wide and caused by upward bulging of the plume.

The East African Rift runs about 3,700 miles from the Ethiopian Plateau south-southwest to South Africas Karoo Plateau. It is up to 370 miles wide and includes mountains reaching a maximum elevation of about 19,340 feet at Mount Kilimanjaro.

The rift is characterized by volcanic peaks, plateaus, valleys and large basins and freshwater lakes, including sites where many fossils of early humans and their ancestors have been found, says Nahid Gani (pronounced nah-heed go-knee), a research scientist. There was some uplift in East Africa as early as 40 million years ago, but most of these topographic features developed between 7 mil
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