New fossil evidence indicates that ancestors of modern humans may have migrated out of Africa earlier than previously believed—potentially hundreds of thousands of years before Homo erectus, the species long considered the first to venture beyond the continent. This discovery challenges the established timeline of human evolution and raises questions about the diversity of early hominin species.
The Dmanisi Site: A Key to the Past
For three decades, the medieval hilltop town of Dmanisi in Georgia has been an archaeological hotspot. Recovered skulls dating back 1.8 million years reveal one of the oldest known human settlements outside Africa. These fossils have sparked debate: do they represent a single, highly variable Homo erectus population, or multiple distinct species?
The latest research, published in PLOS One, focuses on dental analysis to resolve this dispute. Unlike previous studies centered on skull morphology, scientists examined 24 teeth from three individuals at Dmanisi, comparing them to a database of over 550 teeth from various hominin species.
Two Distinct Groups Emerge
The tooth analysis revealed a clear division: one group closely resembling Australopithecus (early, ape-like hominins), the other more aligned with later Homo species. This distinction was particularly noticeable in upper jaw teeth. Researchers argue this suggests at least two separate lineages were present in Dmanisi.
“There were likely more than one species that occurred in the Dmanisi region,” explains Mark Hubbe, the study’s co-author. The differences between these groups, he adds, are comparable to those between male and female chimpanzees or gorillas.
Implications for Human Migration
If confirmed, this finding implies that early hominins left Africa before Homo erectus, challenging the long-held narrative of erectus as the first great migrant. These earlier migrants may not have resembled modern humans closely; some may have retained more primitive traits.
Paleoanthropologist Chris Stringer notes, “If one accepts the new study’s conclusions… then the biggest implication is that there was an earlier, and more ‘primitive’ species that migrated out of Africa than generally thought.” This raises the possibility that these early migrants contributed to the evolution of later, geographically isolated hominins such as Homo luzonensis and Homo floresiensis.
Remaining Uncertainties
The study isn’t without its skeptics. Some researchers argue that the observed dental variation could simply reflect natural differences within a single, variable species. Karen Baab, a paleoanthropologist at Midwestern University, suggests a simpler explanation: “to propose a single, albeit highly variable species, where some individuals retain more ancestral features and others are more derived.”
Further research—including more complete fossil discoveries and advanced genetic analysis (if possible)—is needed to definitively resolve the debate.
In conclusion, this study adds weight to the idea that human migration out of Africa was more complex and earlier than previously assumed. While uncertainties remain, the evidence suggests that multiple hominin species may have ventured beyond Africa before Homo erectus, reshaping our understanding of early human evolution.
