Homo erectus has long occupied a special place in human evolution. It is a species often portrayed as a clean break from more primitive human ancestors, marked by bigger brains, modern body proportions, and the first great migrations out of Africa.
However, a newly reconstructed fossil from Ethiopia suggests that this evolutionary milestone was anything but tidy.
In a study published in Nature Communications, researchers report a detailed reconstruction of a 1.6–1.5 million-year-old skull from Gona, Ethiopia, known as DAN5/P1. The results reveal a striking mosaic of traits that blurs the boundary between early members of the genus Homo and classic Homo erectus. This challenges the traditional view that our ancestors underwent rapid transformation in clearly distinct stages, highlighting instead how overlapping features complicate a simple evolutionary narrative.
In the study, researchers argue that the emergence of Homo erectus was not a simple evolutionary handoff from smaller-brained ancestors to a more advanced, uniform species. Instead, multiple forms of Homo appear to have coexisted in Africa for hundreds of thousands of years, evolving along partially independent paths.
“We already knew that the DAN5 fossil had a small brain, but this new reconstruction shows that the face is also more primitive than classic African Homo erectus of the same antiquity,” lead-author and paleoanthropologist at Midwestern University in Arizona, Dr. Karen Baab, said in a press release.“One explanation is that the Gona population retained the anatomy of the population that originally migrated out of Africa approximately 300,000 years earlier.”
A rare and revealing skull
The DAN5/P1 fossil is unusually important because of its completeness and the location where it was found. The specimen was recovered from the DAN5 locality at Gona in northeastern Ethiopia, a region already well known for preserving some of the earliest stone tools and hominin remains in the archaeological record.
Excavated during systematic fieldwork in sediments dated to roughly 1.6 to 1.5 million years ago, the fossil was initially identified as a partial cranium. Crucially, fragments of the braincase, face, and dentition were preserved together rather than scattered across the landscape. That kind of association is rare for the Early Pleistocene, when erosion and geological processes typically leave researchers with isolated pieces rather than intact individuals.
In the case of DAN5/P1, the fragments came from a single individual and retained clear anatomical relationships. This enabled researchers to apply high-resolution micro-CT scanning and advanced virtual reconstruction techniques to digitally reassemble both the cranial vault and much of the face. The result is one of the most complete early Homo crania ever recovered from the Horn of Africa.
The timing of the fossil makes it especially significant. DAN5/P1 dates to a pivotal moment in human evolution, around 1.6 million years ago, when Homo erectus is thought to have firmly established itself in Africa and begun spreading beyond the continent.
Classic African Homo erectus fossils from Kenya—such as KNM-ER 3733 and the famous “Turkana Boy”—already display many hallmark traits by this period, including larger brains, prominent brow ridges, and reduced teeth.
However, DAN5/P1 reveals contrasts with this established story.
While parts of the skull, especially the brow ridge and overall cranial architecture, resemble Homo erectus, the face and teeth retain more primitive features associated with earlier species, such as Homo habilis. The brain size, estimated at about 36.5 cubic inches, is small, overlapping with early Homo and well below the average for African Homo erectus.
This combination makes DAN5/P1 one of the clearest examples yet of a morphological “in-between”—a single individual that preserves traits evolutionary textbooks often separate into neat categories.
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