SÃO PAULO, BRAZIL—A report from Phys.org explains that Victory Nery of the University of São Paulo, along with his research team, proposes that fossils uncovered at the Dmanisi site in the Republic of Georgia between 1999 and 2005 belong to two separate species. This collection includes hundreds of fossils, among them five skulls, which have been dated to around 1.85 to 1.77 million years ago. Since Homo erectus is believed to have left Africa approximately 1.8 million years ago, the researchers questioned whether other hominin species may have migrated out of Africa during the same period.

The Dmanisi skulls show notable differences from Homo erectus and do not all closely resemble one another, particularly in terms of size. Because of this variation, the researchers concentrated on examining the surface area of the premolars and molars from three of the Dmanisi skulls. They compared the size and shape of these teeth with an existing database containing dental information from Australopithecus and several other hominin species. In total, nearly 600 hominin teeth were analyzed, and a statistical sorting method was used to create a biological map distinguishing different species.

The results of this analysis suggest that the three individuals from Dmanisi did not all belong to the same group. One specimen, known as Dmanisi Skull 5, which has a relatively small braincase and a large, projecting face, was classified as more apelike. In contrast, the teeth from the other two skulls were found to be more similar to those of modern humans. The team also compared the Dmanisi teeth with those of great apes, which typically show size differences between males and females. Based on this comparison, Nery and his colleagues determined that sexual dimorphism could not explain the range of variation seen in the Dmanisi fossils. As a result, they propose that the more apelike individual be identified as Homo georgicus, while the more human-like individuals be classified as Homo caucasi.