Richard Leakey has spent a lifetime exploring Kenya's Turkana Basin searching for the origins of man.
Each layer of sediment, says the paleoanthropologist and founder of the Turkana Basin Institute, helps to tell the narrative of human evolution.
"You get the whole story of life represented going back from the present right back to the beginnings of an ape that has two legs as opposed to four," Leakey said.
"So the whole story of humanity you can actually trace to the Turkana Basin."
But Leakey says these ancient hills tell another story, a history of climactic changes that gave rise to some species and led to the extinction of others. more