How Drought Spurred Evolution of Human Intelligence

According to new research, humans evolved their very large brains in response to the dramatic shifts in the climate of East Africa, the cradle of humanity where man's ancestors are thought to have originated about two million years ago. Scientists have matched exceptionally wet periods and very dry periods in the East African Rift Valley to sudden spurts in the evolution of the hominid ancestors of Homo sapiens, which resulted in the evolution of the modern human brain. Academics have long argued about what led to the unusually large brain of humans with its capacity for language, abstract thought, and consciousness. The latest theory suggests it was triggered by the need to adapt to dramatic changes in the local environment of early man.