First Humans' African Home Gets New Birth Date

Twenty-five million years ago, as plate tectonics began to pull apart eastern Africa, the landscape that would eventually be home to the first humans began to take shape.

Now, new research says that landscape — and its lakes, rivers and climate — may have looked quite different than scientists thought. 

The East African Rift Valley, as the region is known, formed where the Somalian and Nubian plates are pulling away from the Arabian Plate. The eastern branch of the rift passes through Ethiopia and Kenya, and the western branch forms a giant arc from Uganda to Malawi....