Skulls of Homo erectus (right) and a Homo habilis,1-2 million years old, found near Lake Turkana on display in the Koobi Fara museum in a remote area of Sibiloi National Park, Kenya, one of the leading prehistoric sites to study human evolution. The African Homo erectus (also called Homo ergaster) was the first human ancestor to move out of Africa into the colder northern climates about 1.8 million years ago.