Dmanisi fossils suggest Homo erectus may not have been the first to leave Africa

A PLOS One study compared 24 teeth from three individuals at Dmanisi with 559 teeth from other hominins and found dental variation that groups into two sets, which the authors say could indicate more than one species lived at the site about 1.8 million years ago.

A new analysis of fossil teeth from Dmanisi, Georgia, finds dental differences that researchers say point to more than one human lineage at the site about 1.8 million years ago. The study, published in PLOS One on Dec. 3, focused on teeth rather than skulls and compared 24 Dmanisi teeth with 559 teeth from other hominins. Excavations at Dmanisi about 35 years ago recovered five skulls and made the site one of the oldest-known locations for human species outside Africa. Resolving the variation at Dmanisi could affect ideas about which human species first left Africa. Key findings: - Researchers analyzed 24 teeth from three individuals at Dmanisi and compared them with 559 teeth from australopiths, early Homo species and modern humans. - Upper-jaw teeth appeared to split into two groups: one set more similar to australopiths and another more similar to early Homo. - The authors interpret this pattern as consistent with more than one species being present at Dmanisi around 1.8 million years ago. - Some experts quoted in the article agree that multiple lineages are plausible, while others caution the variation could reflect a single, highly variable species. - If accepted, the results would imply a more primitive species left Africa before Homo erectus, but that conclusion remains debated. Summary: If the two-species interpretation holds, it would imply an earlier, more primitive human lineage dispersed out of Africa before Homo erectus. Experts are divided, with some supporting multiple lineages at Dmanisi and others viewing the differences as intraspecies variation. Further analyses and scholarly debate are ongoing. Undetermined at this time.