Photo: Karen L. Baab and National Museum of Ethiopia
Estimated to be 1.5 million years old
Scientists have reconstructed the head of an ancient human relative using 1.5-million-year-old teeth and bone fragments, and the resulting face is complicating established views of early human evolution, Live Science reports.
The reconstructed skull, known as DAN5, shares several traits with Homo erectus—one of the earliest human ancestors with modern body proportions that spread beyond Africa. However, it also displays features typical of the earlier species Homo habilis, suggesting a more complex evolutionary transition than previously thought.
The fossil remains of DAN5 were discovered in the Gona region of northern Ethiopia and were first described in a 2020 study. They are dated to approximately 1.5–1.6 million years ago. Based on its size, researchers believe the skull belonged to a small male Homo erectus.
“We already knew that the DAN5 fossil had a small brain, but this new reconstruction shows that the face is also more primitive than that of classic African Homo erectus of the same age,” said Karen Baab, a paleoanthropologist at Midwestern University in Arizona and a co-author of the study. She added that the population from the Gona region may have “retained the anatomy of a population that initially migrated out of Africa around 300,000 years earlier.”
To reconstruct the face, researchers used micro-computed tomography (micro-CT) scans of 10 fossil remains—five facial bone fragments and five teeth—allowing them to create a detailed three-dimensional model of the skull.
While the overall shape of the braincase resembled that of Homo erectus, certain facial features—including large molars and a flat, narrow nose—were more characteristic of the older species Homo habilis.
A similar mix of primitive and more advanced traits has previously been observed in 1.8-million-year-old Homo erectus fossils found in Dmanisi, Georgia. This led some researchers to propose that Homo erectus evolved in Eurasia from an earlier Homo population.
However, older Homo erectus fossils of the same age have also been found in Africa. DAN5 is the first African fossil to show the same combination of traits as the Dmanisi hominins, potentially supporting the idea that Homo erectus evolved primarily in Africa, like earlier hominins. At the same time, the fact that DAN5 is younger than the Dmanisi fossils further complicates the picture, suggesting that this blend of old and new features may have persisted in Africa for at least 300,000 years.
Going forward, researchers plan to compare DAN5 with million-year-old human remains from Europe, including fossils identified as Homo erectus and Homo antecessor, a later human relative that lived between 1.2 and 0.8 million years ago. Such comparisons could help clarify the diversity of facial forms within the early Homo genus.
Previously, scientists also suggested that “Little Foot,” the most complete hominin fossil discovered to date, may represent a previously unknown human ancestor species, distinct from other skeletons found in the same cave system in South Africa.
