Dance of Human Evolution Was Herky Jerky, Fossils Suggest

"A trio of anthropologists has decided it's time to rewrite the story of human evolution."

"That narrative has always been a work in progress, because almost every time scientists dig up a new fossil bone or a stone tool, it adds a new twist to the story. Discoveries lead to new arguments over the details of how we became who we are."

"But anthropologists generally agree on this much: A little more than 2 million years ago in Africa, the human lineage emerged. Smithsonian anthropologist Rick Potts says the conventional wisdom is that much of Africa changed about then from forest to dry savanna. Our ape-like ancestors had to adapt or die, leave the forest and embrace the savanna — and in doing so, they evolved into something more like us."