Scientists analyzing ancient Homo erectus teeth found protein mutations that suggest the species may have left a genetic legacy in later hominins [1].
This discovery challenges the traditional branching tree model of human evolution. By identifying shared proteins, researchers are attempting to determine if Homo erectus interbred with other species or served as a direct ancestor to those who came later [1, 2].
The research team sampled teeth from six individuals [4]. These fossils, recovered from sites in present-day China, date to roughly 400,000 years ago [3, 4]. Using proteomic analysis, the team identified two specific enamel-protein mutations that link Homo erectus to Denisovans [5].
Interpretations of these findings vary among experts. Some researchers said these dental proteins provide the first genetic evidence that Homo erectus mated with Denisovans [4]. Other analysts said that Homo erectus may be a direct ancestor of Denisovans rather than a separate population that interbred [6].
The study also examined the connection to present-day populations. Some reports indicate that certain modern human populations carry the protein signal found in these ancient teeth [1]. However, other interpretations of the data suggest the study only raises the possibility of interbreeding without confirming a direct legacy in modern humans [3].
The research was published in Nature this month [1]. The use of protein analysis allows scientists to extract data from fossils that are too old for traditional DNA sequencing, which typically degrades over time, providing a new window into the East Asian prehistoric record [4].
“Homo erectus may have left a genetic legacy in people today”
This research indicates that human evolution was likely a web of interbreeding and overlap rather than a series of clean splits. If Homo erectus contributed genetically to Denisovans and modern humans, it suggests that this ancient species played a more active role in shaping the modern human genome than previously believed.
