Extinct yak relative identified from DNA in Denisova Cave bone fragments

Centre · 2Researchers have identified a previously unknown extinct species of bovine from DNA in bone fragments recovered at Denisova Cave in the Altai foothills of Siberia, Russia, and it is currently known only as "yak X". 1 2 Centre · 1Love Dalén of Stockholm University and colleagues began studying the fragments hoping to learn about bison evolution, but found that nearly all of them carried DNA matching no living bovine, nor the extinct steppe bison or aurochs. 1 Centre · 2The team analysed hundreds of tiny fragments from the cave plus material from three other nearby sites and one near the Ural mountains, and constructed genomes from 20 individuals spanning roughly 200,000 years. 1 2

Centre · 1The Times of India, citing a Phys Org report, says the work was published in Current Biology and involved the Center for Paleogenetics in Stockholm, the University of California, Santa Cruz, and the University of Vienna. 2 Centre · 2The lineage appears to have diverged from the wild yak (Bos mutus) around 400,000 years ago, become genetically isolated by about 250,000 years ago, and gone extinct by around 30,000 years ago; the youngest specimen examined dates to about 27,000 years ago. 1 2 Centre · 1Dalén compared the divergence time to that between polar bears and brown bears, suggesting yak X was probably quite a different animal, just as American and European bison are no longer the same species. 1

Centre · 1The Times of India, relaying Phys Org, says the split coincided with a strong warm period around 400,000 years ago, and that around 120,000 years ago, in the last interglacial, the animal appears to have undergone a population replacement with declining genetic diversity. 2 Centre · 1Researchers found little evidence that it interbred with steppe bison or aurochs. 2 Centre · 1Dalén suspects yak X may correspond to yak-like remains previously described by Russian palaeontologists as a subspecies of the Himalayan yak, but the team does not yet know what unique traits it had until further work, including on possibly misidentified remains, is complete. 1

Centre · 1All the bones found so far come from much lower elevations than the modern yak's native Tibetan Plateau range, which Jonas Oppenheimer of Stockholm University said may mean yak X was less adapted to extreme mountain environments. 1 Centre · 1There is no direct evidence yet that it was hunted by Denisovans, Neanderthals or modern humans, but Dalén says it is likely they and carnivores such as hyenas and lions preyed on it. 1 Centre · 1The cause and exact timing of its extinction remain unknown, and the species has no formal scientific name. 2