After eight years spent studying a 1.8-million-year-old skull uncovered in the Republic of Georgia, scientists have made a discovery that may rewrite the evolutionary history of our human genus Homo.
It would be a simpler story with fewer ancestral species. Early, diverse fossils — those currently recognized as coming from distinct species like Homo habilis, Homo erectus and others — may actually represent variation among members of a single, evolving lineage.
In other words, just as people look different from one another today, so did early hominids look different from one another, and the dissimilarity of the bones they left behind may have fooled scientists into thinking they came from different species.
This was the conclusion reached by an international team of scientists led by David Lordkipanidze, a paleoanthropologist at the Georgian National Museum in Tbilisi, as reported Thursday in the journal Science.
The key to this revelation was a cranium excavated in 2005 and known simply as Skull 5, which scientists described as “the world’s first completely preserved adult hominid skull” of such antiquity. Unlike other Homo fossils, it had a number of primitive features: a long, apelike face, large teeth and a tiny braincase, about one-third the size of that of a modern human being. This confirmed that, contrary to some conjecture, early hominids did not need big brains to make their way out of Africa.