NEW YORK (GenomeWeb) – A paleoproteomic study appearing in the Proceedings of the National Academy of Sciences today indicates that the ancient Châtelperronian people were Neanderthals.
Châtelperronian sites in central France and Spain date back to the Upper Paleolithic period, or some 40,000 years to 50,000 years ago, around the time that anatomically modern humans began to displace Neanderthals in Western Europe. These sites contain artifacts like bone awls, bone pendants, and colorants — items that some say are typical of modern humans. However, hominin remains linked stratigraphically to the Châtelperronian sites morphologically appear to be Neanderthal.
Researchers from the Max Planck Institute for Evolutionary Anthropology and elsewhere used a proteomic approach to study additional bone specimens from Châtelperronian layers and analyze their amino acid sequences. By comparing those sequences with those from modern humans, Neanderthals, and Denisovans, they homed in on an archaic-derived amino acid sequence for a collagen protein, suggesting that the bone fragments at the Châtelperronian site were Neanderthal in nature.
"To differentiate between modern humans, Neanderthals, 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," first author Frido Welker from Max Planck and the University of York said in a statement. "These ancient hominin proteins in Pleistocene bones hold valuable phylogenetic and physiological information."
Welker and his colleagues used ZooMS, a zooarchaeology by mass spectrometry approach, to screen 196 bones that couldn't be taxonomically or morphologically identified from the Châtelperronian Grotte du Renne site in France. In particular, the researchers examined the samples' collagen type I sequences and compared them against a database of genera living in Western Europe during the Late Pleistocene. From this, they uncovered 28 bone fragments belonging to members of the Pan-Homo clade.
By drawing on an error-tolerant liquid chromatography tandem mass spectrometry approach, Welker and his colleagues analyzed the protein content of the ZooMS extracts. From this, they identified 73 proteins and noted that the extracts contained proteins expressed during bone formation. In particular, they reported the presence of COL10α1, which is secreted during bone ossification. A gene ontology analysis likewise indicated an enrichment of bone ossification and cartilage formation processes. In combination with osteological and isotopic data, the researchers said that these findings are consistent with the bones being from a breastfed infant.
"To identify proteins related to specific developmental stages of bone formation highlights one of the main strengths of ancient protein research, especially in a multi disciplinary context," York researcher Matthew Collins noted.
After comparing these protein sequences to those found among modern humans, Neanderthals, and Denisovans, the researchers narrowed in on COL10α1. The version of COL10α1 in their samples harbored an amino acid state that's present in Neanderthals, Denisovans, and 0.9 percent of modern humans, but not in other great apes. In addition, the sliver of modern humans with this version was from populations outside of sub-Saharan Africa with known archaic introgression. This suggested to the researchers that their sample had archaic human ancestry in their nuclear genomes.
Meanwhile, mitochondrial analysis of two of the samples likewise suggested an ancient origin, notably Neanderthal. In addition, isotopic and radiocarbon dating of the samples further confirmed that they were from the Châtelperronian time and not from a different rock layer as some had suggested.
All in all, this indicates that the Châtelperronian people were Neanderthals, the researchers said, and were likely among the latest Neanderthals in western Eurasia.