This was around the time that modern humans were replacing the Neanderthals that inhabited the area, which has been used by some archaeologists to argue that the artifacts were made by modern human hands — particularly by those who believe Neanderthals were cognitively incapable of the symbolic expression required to make jewelry. However, since their discovery, the source of these bones and beads has been hotly debated.
Though the artifacts were found in the same layers as bone fragments, not enough DNA had survived to allow for genetic species identification. So researchers from the Max Planck Institute in Germany and the University of York in the UK decided to turn a newer type of analysis that focuses on ancient protein to figure out the origins of the remains.
The chemical composition of collagen — a structural protein found in connective tissue — in the fragments was compared to that of both modern and archaic humans.
While collagen in modern humans is enriched with an amino acid called aspartic acid, the collagen from the bone fragments contained high levels of another amino acid called asparagine, which matched with previous findings that Neanderthal collagen was asparagine-rich.
Not only did the researchers determine the collagen came from a Neanderthal — providing strong evidence that these archaic humans were also skilled toolmakers and jewelers — but they also concluded it was an infant. The particular form of collagen is only found in growing bone, and the bone also contained levels of nitrogen isotopes that were consistent with a breastfeeding child.
“To identify proteins related to specific developmental stages of bone formation highlights one of the main strengths of this new analysis, especially in a multi-disciplinary context”, said study co-author Matthew Collins, from the University of York, in a press release.
Lead author Frido Welker of the Max Planck Institute for Evolutionary Anthropology adds, “To differentiate between modern humans, Neandertals and Denisovans on the basis of ancient protein research provides really exciting opportunities for future research into the origins of our and their evolutionary history."
The findings were published in Proceedings of the National Academy of Sciences.