Research led by Karen L. Baab, a paleoanthropologist at Midwestern University, is providing new evidence that early human evolution was more complex than previously assumed. By digitally reconstructing a 1.5-million-year-old fossil face discovered in Ethiopia, the study offers a clearer view of the anatomical diversity present among early members of the genus Homo during a critical period of human dispersal.
Baab, K. L., Kaifu, Y., Freidline, S. E., Rogers, M. J., & Semaw, S. (2025). New reconstruction of DAN5 cranium (Gona, Ethiopia) supports complex emergence of Homo erectus. Nature Communications, 16(1), 10878. https://doi.org/10.1038/s41467-025-66381-9
The fossil, known as DAN5, was recovered from the Gona site in the Afar region of Ethiopia and dates to between 1.6 and 1.5 million years ago. It represents the most complete Early Pleistocene hominin cranium yet identified from the Horn of Africa. While DAN5 has been classified as Homo erectus, its facial anatomy does not fully match the features typically associated with that species at the same time period.
Karen L. Baab, a paleoanthropologist at Midwestern University stated,
“It is remarkable that the DAN5 Homo erectus was making both simple Oldowan stone tools and early Acheulian handaxes, among the earliest evidence for the two stone tool traditions to be found directly associated with a hominin fossil.”
The reconstruction combines a previously described braincase with several facial fragments and teeth that were recovered from the same individual. Using high-resolution micro-CT scanning and three-dimensional modeling, researchers digitally reassembled the fragments, adjusting their fit through multiple iterations until anatomical consistency was achieved. This process took nearly a year and relied on established principles of craniofacial structure rather than speculative reconstruction.
The completed model reveals a combination of traits that cross established boundaries between early Homo species. While the braincase shows characteristics consistent with Homo erectus, the face and teeth retain features more commonly associated with earlier hominins, such as a flatter nasal bridge and relatively large molars. These traits had previously been observed in fossils from Eurasia but not in African specimens of similar age.
The findings challenge the idea that Homo erectus followed a single, linear evolutionary path after emerging in Africa. One interpretation is that the population represented by DAN5 retained ancestral features from earlier groups that had already begun dispersing beyond the continent. Another possibility is that multiple populations with differing anatomical traits coexisted within Africa, exchanging genes or adapting locally over time.
The fossil was discovered as part of the Gona Paleoanthropological Research Project, which has documented both hominin remains and stone tools spanning more than six million years. At the DAN5 site, researchers found evidence of both Oldowan tools and early Acheulean handaxes. The coexistence of these tool traditions alongside a single individual suggests that technological transitions did not necessarily correspond to sharp biological changes.
Comparative analysis with other African and Eurasian fossils indicates that early Homo populations displayed a wider range of variation than previously recognized. This growing body of evidence supports a view of human evolution shaped by regional diversity, migration, and interaction rather than a straightforward progression from one form to another.
From a broader scientific perspective, the study demonstrates how digital reconstruction techniques are reshaping paleoanthropology. High-resolution imaging and computational modeling allow researchers to revisit fragmentary fossils and extract new information without physical alteration. As more fossils are scanned and compared, these methods are likely to refine how species boundaries and evolutionary relationships are defined.
Future research will focus on comparing the DAN5 cranium with other early human fossils from Africa and Europe, including specimens dated to around one million years ago. Researchers hope that additional discoveries from the one-to-two-million-year window will clarify whether DAN5 reflects population diversity within Homo erectus, interaction between species, or a transitional form that does not fit neatly into existing categories.
Rather than rewriting human evolution outright, the reconstructed face from Gona adds resolution to a picture that is already becoming more detailed and complex. It suggests that early humans shared a mix of traits shaped by migration, local adaptation, and time, reinforcing the idea that evolutionary change rarely follows a single path.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
