Did Climate Change Trigger Human Evolution?

Researchers say the growth of arid grasslands at the expense of tropical forests may have prompted the first humans to split off from other primates. For instance, a study in the journal Nature in 2004 identified adaptations for running in human fossils more than two million years old. These adaptations may have enabled early humans to chase down prey on the open plains of Africa, researchers said. (See "Humans Were Born to Run, Fossil Study Suggests.")

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More recent research, published last year in Science, suggested that a period of more sudden, regional climate fluctuation played a key role in human development.

Analysis of soil layers in the Great Rift Valley showed evidence for three unusually wet periods between 2.7 and 1 million years ago.

Fossils of aquatic algae indicated the presence of extinct lakes, some more than 328 feet (100 meters) deep, which quickly formed then disappeared.

Researchers say the lakes are evidence of the type of rapid climate swings that might have driven human evolution, forcing populations to adapt and readapt to cope with fast-changing environmental conditions.

"What are the implication for the current debate over global warming? I feel strongly that there is evidence that everytime there is a major shift or lasting change in human development there is an accompanying climatic or for lack of a better term earth centered event. Starting with the origin of the species a drying up of the forests. Next the ice age may have played a role in the development of neandertals and their big brains which many believe started language.Then a warmer period allowing for agriculture. Then the collapse of the Roman empire after a cooling period puts population pressure on the food supply in Northern Europe known as the little ice age. Followed by a warming period that made agriculture flourish in Northern Europe followed by another cold period that may have spurred world exploration and now Global warming.The social change accompanying global warming is a little different though. Clearly we have changed our orientation towards the future or nature has pushed us in this direction.We don't think about the future anymore and so our values have changed too. This has been caused by population pressures.