Scientists rewrite human evolution timeline
Scientists have synthesized a new theory that the traits that have allowed humans to adapt and thrive in a variety of varying climate conditions evolved in Africa gradually and at separate times.
Many traits unique to humans were long thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa and it was earlier believed that large brain, long legs, the ability to craft tools and prolonged maturation periods have evolved together at the start of the Homo lineage as African grasslands expanded and Earth's climate became cooler and drier.
However, the new analysis suggested that these traits did not arise as a single package but several key ingredients once thought to define Homo evolved in earlier Australopithecus ancestors between 3 and 4 million years ago, while others emerged significantly later.
Richard Potts, Smithsonian paleoanthropologist, has developed a new climate framework for East African human evolution that depicts most of the era from 2.5 million to 1.5 million years ago as a time of strong climate instability and shifting intensity of annual wet and dry seasons.
Susan Anton, professor of anthropology at New York University, said that they could tell the species apart based on differences in the shape of their skulls, especially their face and jaws, but not on the basis of size and the differences in their skulls suggest early Homo divvied up the environment, each utilizing a slightly different strategy to survive.
Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research, said that the data suggested that species of early Homo were more flexible in their dietary choices than other species, while the team also concluded that this flexibility likely enhanced the ability of human ancestors to successfully adapt to unstable environments and disperse from Africa.
The study is published in the issue of Science.
(Posted on 04-07-2014)