Ancient proteins in Homo erectus teeth reveal DNA link to modern humans via Denisovans
Proteins extracted from Homo erectus teeth suggest the species interbred with Denisovans, passing some DNA to modern humans. This fills a gap in human ancestry previously hinted at by the Denisovan genome.
Ancient proteins found in Homo erectus teeth suggest that this early human species interbred with Denisovans, and that some of their DNA eventually made its way into modern humans.
Human ancestry has become much clearer thanks to ancient DNA. As humans left Africa, they interbred with Neanderthals and Denisovans. But the Denisovan genome also hinted at interbreeding with an even older group, whose identity was unknown.
Now, protein evidence points to Homo erectus as that mystery group. Homo erectus left Africa over a million years ago and spread across Eurasia. Through Denisovans, some of their DNA appears to have been inherited by modern humans.
DNA degrades quickly without cellular repair enzymes. The double helix fragments, and bases change or fall off. Cooler, drier environments slow this, but there's a limit to how far back we can sequence DNA. Homo erectus remains seem to be beyond that limit.
Proteins, however, can last longer. Researchers analyzed protein sequences from Homo erectus teeth and found matches with Denisovan DNA, indicating interbreeding. This suggests a genetic link that persisted through Denisovans to us.
The finding helps clarify the complex web of ancient human interactions. It shows that interbreeding was common among archaic human groups, not just between modern humans and Neanderthals.