On Feb. 10, 2016, the face of a ghost emerged from weathered Ethiopian sandstone. The nearly complete skull, 3.8 million years old, was found less than 20 miles from the site where Lucy, the most famous of our distant evolutionary relatives, was discovered in the 1970s.
Lucy was a member of the species Australopithecus afarensis. This new find, however, was something different.
As paleoanthropologists analyzed the skull and compared it with other hominins, members of our family tree, two things became clear: They were coming face-to-face with a species for the first time, and it would challenge the traditional model of hominin evolution.
