Scientists have uncovered the first known Denisovan radius bone—part of the forearm—in Southwest China, dating back to the late Middle Pleistocene. This discovery, made in a site called Bianfu Cave in Yunnan province, adds important details to the understanding of Denisovans, a group of ancient humans closely related to Neanderthals and modern humans. The research team, led by Professor Fu Qiaomei from China's Institute of Vertebrate Paleontology and Paleoanthropology, identified five hominin remains from the site, helping to fill a gap in the geographic distribution of Denisovans in China. The study, published in the journal Nature, used a new method combining morphological screening with a technique called ZooMS (Zooarchaeology by Mass Spectrometry) to identify hominin fossils more efficiently. This method is crucial because hominin fossils are extremely rare at Paleolithic sites, often making up less than 0.1% of all bone fragments. At Bianfu Cave, where over 60,000 bone fragments were found, the new approach allowed researchers to identify five hominin remains, including the first confirmed Denisovan radius. The researchers found that the Denisovan remains came from two different layers of the cave. The three newly identified bones—two parietal bones and a partial radius—were dated to between 134,000 and 167,000 years ago. Further analysis of proteins in the samples confirmed their Denisovan identity, showing that they shared specific genetic markers with other Denisovan fossils. The study also used advanced genetic techniques to build evolutionary trees, showing that the Bianfu Cave Denisovans are closely related to other Denisovans and distinct from earlier human species like Homo erectus. The newly discovered radius bone offers unique insights into Denisovan anatomy and behavior. Though it shares some features with Neanderthal bones, its overall shape is more similar to modern human radii. Researchers suggest that this structure may have allowed Denisovans to perform lightweight, precise movements, which could have been useful for tool use or hunting. The discovery also indicates that Denisovans living near Bianfu Cave had distinct physical and behavioral traits compared to other hominin groups of the time. Bianfu Cave was used by Denisovans for over 100,000 years, from around 190,000 to 70,000 years ago. In addition to the human fossils, the researchers found nearly 1,400 stone tools, over 64,000 mammal bones, and four teeth from an unknown human lineage. The Denisovan tools, made primarily from local materials, suggest a practical, efficient approach to survival. The presence of both stone and bone tools also hints that Denisovans, like Neanderthals, may have used a variety of materials for daily tasks, challenging previous assumptions about the extent of tool use among ancient human populations.