How Many Hominin Species Migrated Out of Africa?

SÃO PAULO, BRAZIL—According to a Phys.org report, Victory Nery of the University of São Paulo and his colleagues suggest that fossils discovered at the site of Dmanisi in the Republic of Georgia between 1999 and 2005 represent two distinct species. The hundreds of fossils in the group, including five skulls, have been dated to between 1.85 and 1.77 million years ago. Homo erectus is thought to have migrated out of Africa some 1.8 million years ago. Did other species migrate out of Africa as well at this time? The Dmanisi skulls differ from Homo erectus, do not all resemble each other, and vary in size. The scientists therefore focused on the surface area of the premolars and molars of three of the Dmanisi skulls, and compared the sizes and shapes of these teeth with a database of information on Australopithecus and several other hominin species. Then they analyzed nearly 600 hominin teeth and created a biological map of the different species with a statistical sorting tool. The map indicates that the three Dmanisi individuals were not all from the same group. Dmanisi Skull 5, which has a small braincase and massive, protruding face, was categorized as more apelike, while the teeth from the other two skulls were determined to be more like those of humans. The researchers also compared the Dmanisi teeth with the teeth of great apes, which vary in size among males and females. Nery and his team concluded that size differences could not account for the variety observed in the Dmanisi teeth. They therefore suggest that the more apelike Dmanisi individual be classified as Homo georgicus, and the more human-like group be called Homo caucasi. Read the original scholarly article about this research in PLOS One. For more on the Dmanisi skulls, go to “Homo erectus Stands Alone,” one of ARCHAEOLOGY’s Top 10 Discoveries of 2013.