Louise Leakey is the third generation of her family to dig for humanity's past in East Africa. In 2001, Leakey and her mother, Meave, found a previously unknown hominid, the 3.5-million-year-old Kenyanthropus platyops, at Lake Turkana -- the same region where her father, Richard, discovered the "Turkana Boy" fossil, and near Tanzania's Olduvai Gorge, where her grandparents, Louise and Mary Leakey, discovered the bones of Homo habilis.

In August 2007 Louise and Meave, both National Geographic Explorers-in-Residence, dug up new H. habilis bones that may rewrite humanity's evolutionary timeline. We imagine that we evolved from apes in an orderly progression from ape to hominid to human, but the Leakeys' find suggests that different species of pre-humans actually lived side by side at the same time for almost half a million years.