Scientists long have focused on how climate and vegetation allowed human ancestors to evolve in Africa. Now, University of Utah geologists are calling renewed attention to the idea that ground movements formed mountains and valleys, creating environments that favored the emergence of humanity.
Tectonics [movement of Earths crust] was ultimately responsible for the evolution of humankind, Royhan and Nahid Gani of the universitys Energy and Geoscience Institute write in the January, 2008, issue of Geotimes, published by the American Geological Institute.
They argue that 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.
Because of the crustal movement or tectonism in East Africa, the landscape drastically changed over the last 7 million years, says Royhan Gani (pronounced rye-hawn Go-knee), a research assistant professor of civil and environmental engineering. That landscape controlled climate on a local to regional scale. That climate change spurred human ancestors to evolve from apes.
Hominins the new scientific word for humans (Homo) and their ancestors (including Ardipithecus, Paranthropus and Australopithecus) split from apes on the evolutionary tree roughly 7 million to 4 million years ago. Royhan Gani says the earliest undisputed hominin was Ardipithecus ramidus 4.4
|Contact: M. Royhan Gani|
University of Utah