New 250,000-Year-Old Yak Species Discovered Amongst Bone Fragments Found in Famous Cave

A previously unknown relative of modern yaks, referred to as “yak X,” has been identified by researchers using ancient DNA obtained from bone fragments found in Siberia’s Denisova Cave and surrounding areas. This significant discovery was published in *Current Biology* on 5 October and originates from a collaborative effort between Stockholm University and the Swedish Museum of Natural History.

The research team managed to extract 20 genomes from remains that date back between 247,000 and 27,000 years, revealing crucial insights about the evolutionary history of yaks. As described by Love Dalén, a senior author and professor of evolutionary genomics, the identification of yak X was made possible despite the fragments being too small and damaged to be classified by morphological characteristics alone. “This is a remarkable discovery of a large extinct species based on small non-diagnostic bones,” Dalén remarked. He emphasised the need for further DNA recovery from well-preserved specimens to enable a comprehensive description of the species.

In terms of its evolutionary timeline, yak X is believed to have diverged from the ancestors of modern yaks approximately 400,000 years ago, becoming fully distinct around 250,000 years ago. While the exact size and physical attributes of yak X remain unclear, researchers speculate that it may have resembled the Himalayan yak, sharing a relatively recent common ancestor. Nonetheless, Dalén cautioned that differences in appearance can be substantial even among closely related species, noting the divergence of brown and polar bears around the same time.

Denisova Cave, where these bones were discovered, is renowned for the historic DNA findings related to an extinct species of ancient humans known as Denisovans, identified in 2010. Evidence suggests that yak X lived in proximity to this site during a period when early human species, including Denisovans and Neanderthals, were also present. While there is no direct evidence to confirm interactions, Jonas Oppenheimer, a postdoctoral researcher involved in the study, believes it is plausible that these ancient humans may have hunted yak X.

The research into yak X does not stop at its discovery. The team is currently investigating which particular protein-coding genes differentiate yak X from its Himalayan relatives. This focus on genetic divergence not only aims to illuminate the characteristics of yak X but also sheds light on the wider biodiversity of the Altai region during the Pleistocene epoch—a time marked by glacial cycles.

Oppenheimer highlighted the ecological significance of the Altai region, suggesting it acted as a biodiversity hotspot and possibly a refuge during periods of climatic upheaval. The variety of species that thrived in this area may provide insights into how early human populations managed to coexist with such diverse wildlife. He indicated that recent models propose a stable environment in the region, which likely facilitated the survival of various species amidst the drastic climate shifts characteristic of the Pleistocene.

The uncovering of yak X contributes valuable information to the existing understanding of prehistoric ecosystems and the evolutionary narratives of bovine species. As researchers continue to explore the genetic foundations that delineate yak X from its modern descendants, they could uncover further insights into the ecological dynamics of the epoch in which these animals lived.

This remarkable finding not only enhances the existing body of knowledge regarding ancient bovines but also opens up new avenues for exploring the interactions between extinct species and early humans. As the research progresses, it promises to deepen the understanding of how these ancient beings adapted to their environments and the implications for their survival as climate conditions fluctuated dramatically over millennia.

Through ongoing investigation and analysis, the scientific community is poised to learn more about the complex tapestry of life that existed alongside our ancestors, further enriching the narrative of human evolution and species adaptation.