A fossil Pleistocene-age hominin jawbone discovered in Taiwan has now been identified as belonging to a Denisovan, according to a new paleoproteomic analysis of the remains. The findings provide direct molecular evidence that Denisovans occupied diverse climates, from the cold Siberian mountains to the warm, humid subtropical latitudes of Taiwan, and offer new morphological insights into this enigmatic hominin lineage. Recent research has revealed a surprising variety of ancient human relatives that lived in eastern Asia during the Pleistocene before modern humans arrived. One of the most important discoveries is the Denisovans, a distinct group identified through DNA from fossils in Denisova Cave, Siberia. Studies show that Denisovans were closely related to Neanderthals and interbred with both them and modern humans. However, outside Siberia, direct genetic evidence of Denisovans has only been found on the Tibetan Plateau. While other fossils found across eastern Asia have been proposed as being Denisovan, their classification remains uncertain without molecular confirmation. Here, Takumi Tsutaya and colleagues provide paleoproteomic evidence identifying a fossil hominin mandible (Penghu 1) recovered from the Penghu Channel off Taiwan as belonging to a male Denisovan. The Penghu remains, along with various animal fossils, were retrieved through commercial fishing dredging from the seafloor, which was once part of the Asian mainland during lower sea levels in the Pleistocene. Using ancient proteomic analysis, Tsutaya et al. extracted proteins from bone and dental enamel from the fossil and retrieved 4,241 amino acid residues, two of which were Denisovan-specific protein variants. According to the authors, these variants are rare in modern human populations but have a higher frequency in regions associated with Denisovan genetic introgression. What’s more, morphological analysis of the Penghu 1 remains reveals a robust jaw structure with large molars, and distinctive root structures, features that align with traits seen in the Tibetan Denisovan specimen, suggesting these traits were characteristic of the lineage and perhaps sex-specific.
