A skull of Homo erectus, dated to about 1.55 million years ago, is presented to the media during a news conference held at the National Museums of Kenya in Nairobi, April 9, 2007. The ancient skull and upper jawbone from two early branches of the human family tree -- Homo erectus and Homo habilis -- suggest the early human ancestors may have lived close together for half a million years, researchers said on Wednesday. REUTERS/Radu Sigheti (KENYA)