1.5 million-year-old Homo erectus face was just reconstructed — and its mix of old and new traits is complicating the picture of human evolution
Scientists have reconstructed the head of an ancient human relative from 1.5 million year old fossilized bones and teeth. But the looking-back face complicates scientists’ understanding of early human evolution and dispersal, a new study suggests.
The reconstructed fossil skull, called DAN5, shares features with Homo erectusthe first human relatives to have modern body proportions and to disperse from Africa. But the skull also has some features associated with earlier species. Homo habilis. The results suggest a complex evolutionary path from early human ancestors to H. erectusthe researchers reported December 16 in the journal Natural communications.
“We already knew that the DAN5 fossil had a small brain, but this new reconstruction shows that the face is also more primitive than the classic African face. Homo erectus of the same antiquity”, co-author of the study Karen Baabpaleontologist at Midwestern University in Arizona, said in a statement. This could mean that the population of the Gona region would have “retained the anatomy of the population that initially migrated out of Africa around 300,000 years earlier”, she said.
To reconstruct DAN5’s face, the researchers used micro-computerized tomography (CT) of 10 fossils – five facial bone fragments and five teeth – to create a 3D model. The process was like “a very complicated 3D puzzle, where you don’t know the exact outcome in advance,” Baab said. “Luckily, we know how faces fit together in general, so we weren’t starting from scratch.”
The brain case shape of DAN5 was similar to that of H. erectus. But some facial features, such as the large molars and flat, narrow nose, more closely resembled those of the older human ancestor. H. habilis.
A similar mix of old and new traits had already been observed in animals 1.8 million years old. H. erectus Dmanisi fossils in the Republic of Georgia, leading some scientists to believe that the species evolved in Eurasia from an earlier time. Homo population. Older H. erectus Fossils dating back 1.8 million years have also been discovered in Africa. But DAN5 is the first African fossil to possess the same mix of attributes as the Dmanisi hominins, which could support the hypothesis that H. erectus evolved mainly in Africa, like other hominids before it. Further complicating the situation is the fact that the DAN5 fossils are younger than those from Dmanisi, suggesting that the mix of old and new traits persisted in Africa for at least 300,000 years.
In future work, the team plans to compare the DAN5 fossils to million-year-old human fossils from Europe, some of which have been identified as human fossils. H. erectus and like Homo ancestor — a later human relative who lived 1.2 million to 0.8 million years ago — to better understand variability in early facial shape Homo gender. The team also plans to study whether DAN5 could be a product of crossbreeding between several Homo species.
“We are going to need several additional fossils from between one and two million years ago to resolve this problem,” study co-author Michael Rogersan anthropologist from Southern Connecticut State University, said in the release.
