High-Altitude Cave Reveals Denisovan Presence and Diet
High-Altitude Cave Reveals Denisovan Presence and Diet
The Diet and Survival Strategies of Denisovans on the Tibetan Plateau
For over a century, the study of Neanderthals has provided significant insights into human evolution, revealing the genetic legacy shared with modern humans. However, the discovery of Denisovans, another close relative, was a surprising revelation that came to light only through DNA sequencing of a small finger bone. Since then, our knowledge of Denisovans has remained limited, with sparse fossil records and few clues about their appearance or lifestyle.
The Baishiya Karst Cave
Recent discoveries from the Baishiya Karst Cave on the Tibetan Plateau have begun to shed light on Denisovan life. Situated at an altitude of over 3,000 meters (nearly 11,000 feet), this cave borders a high open plain. The site gained attention when a Tibetan monk discovered a portion of a lower jaw, which was later identified as Denisovan through protein analysis.
The Xiahe mandible, as it is known, remains the most substantial Denisovan fossil to date. Subsequent excavations at Baishiya Karst Cave revealed a rich collection of animal bones and environmental DNA, indicating that Denisovans occupied the cave regularly for at least 100,000 years, surviving through the last two glacial cycles.
Analyzing Bone Fragments with ZooMS
The focus of recent research1 has been on the animal bones found within the cave. Many of these bones were too fragmentary to be identified by traditional methods. Researchers employed a technique called zooarchaeology by mass spectrometry (ZooMS), which involves purifying protein fragments from the bones and using mass spectrometry to separate them based on their mass.
Mass spectrometry can identify specific amino acid sequences unique to different species, allowing researchers to determine the origins of the bone fragments. This technique proved effective, identifying nearly 80 percent of the bone fragments tested.
The Denisovan Diet
ZooMS analysis revealed a diverse array of species that ended up in Baishiya Karst Cave. The most common species was the bharal, or blue sheep, a staple of the Himalayan region. Other species included yaks, horses, gazelles, and two types of deer, suggesting a landscape of open grasslands with some wooded shrublands.
The cave also yielded remains of larger animals like woolly rhinoceroses, along with smaller creatures such as flying squirrels and porcupines. Predators such as spotted hyenas, wolves, and snow leopards were also present, alongside birds like pheasants and golden eagles.
While some animals might have ended up in the cave naturally, many bones showed signs of butchering, including cut marks and evidence of marrow extraction. Rodent and predator damage was minimal, appearing on only 1 percent of the bones, whereas butchering marks were found on nearly 20 percent. Some bones also showed signs of being fashioned into tools.
The lack of predator damage suggests that the Denisovans were not merely scavenging but actively hunting and processing their food. Over time, the composition of the animal remains shifted, with an increasing number of sheep in more recent layers, indicating a possible specialization in hunting practices.
Another Denisovan Bone Discovery
Amidst the animal remains, researchers identified a bone fragment that belonged to a human relative. Detailed collagen sequencing confirmed it as Denisovan, making it one of the larger Denisovan bone samples obtained so far, albeit only a 5-centimeter rib fragment.
This bone fragment was found in a layer where environmental DNA did not indicate Denisovan presence, raising questions about the frequency of their visits or the preservation of DNA. Nevertheless, it confirms that Denisovans were present on the Tibetan Plateau as recently as 30,000 years ago.
Conclusion: Denisovans as Adaptable Survivalists
The findings from Baishiya Karst Cave provide a glimpse into the life and diet of Denisovans, highlighting their adaptability to harsh, high-altitude environments over two glacial periods. Although much remains unknown about their physical appearance and full dietary habits, it is clear that Denisovans were skilled survivalists.
The Denisovan legacy includes genetic contributions to modern human populations, particularly adaptations that help current inhabitants of the Tibetan Plateau cope with high altitudes. As research continues, each new discovery brings us closer to understanding these enigmatic relatives and their place in human evolution.
Xia, H., Zhang, D., Wang, J., Fagernäs, Z., Li, T., Li, Y., Yao, J., Lin, D., Troché, G., Smith, G. M., Chen, X., Cheng, T., Shen, X., Han, Y., Olsen, J. V., Shen, Z., Pei, Z., Hublin, J.-J., Chen, F., & Welker, F. (2024). Middle and Late Pleistocene Denisovan subsistence at Baishiya Karst Cave. Nature. https://doi.org/10.1038/s41586-024-07612-9