Tectonics created ‘Wall of Africa’ allowed humanity to emergeDecember 19th, 2007 - 7:04 pm ICT by admin
Washington, Dec.19 (ANI): University of Utah geologists have claimed that Tectonics” or the movement of the Earths crust, was responsible for the evolution of humankind.
According to Royhan and Nahid Gani, geologists with the universitys Energy and Geoscience Institute, the accelerated uplift of mountains and highlands stretching from Ethiopia to South Africa blocked much ocean moisture, converting lush tropical forests into an arid patchwork of woodlands and savannah grasslands that gradually favored human ancestors who came down from the trees and started walking on two feet an energy-efficient way to search larger areas for food in an arid environment.
In their Geotimes article, the Ganis a husband-and-wife research team who met in college in their native Bangladesh describe this 3,700-mile-long stretch of highlands and mountains as the Wall of Africa.
It parallels the famed East African Rift valley, where many fossils of human ancestors were found.
Hominins the new scientific word for humans (Homo) and their ancestors (including Ardipithecus, Paranthropus and Australopithecus) split from apes on the evolutionary tree roughly seven million to four million years ago.
Royhan Gani says the earliest undisputed hominin was Ardipithecus ramidus 4.4 million years ago. The earliest Homo arose 2.5 million years ago, and our species, Homo sapiens, almost 200,000 years ago.
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.
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.
Although the Wall of Africa started to form around 30 million years ago, recent studies show most of the uplift occurred between seven million and two million years ago, just about when hominins split off from African apes, developed bipedalism and evolved bigger brains, the Ganis write.
The answer, he believes, is the variable landscape and vegetation resulting from uplift of the Wall of Africa, which created a topographic barrier to moisture, mostly from the Indian Ocean and dried the climate. He says that contrary to those who cite global climate cycles, the climate changes in East Africa were local and resulted from the uplift of different parts of the wall at different times. (ANI)
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