DNA from an unknown animal found in a cave occupied by Neanderthals 400,000 years ago has led to the discovery of a new species of bovid, named X yak. The Siberian cave, located at the foot of the Altai Mountains, contains more than 250,000 bone fragments belonging to both humans and mammals. However, about 95% of the skeletal remains are too small and incomplete to be identified based on form alone. Genetic analysis has therefore revealed some of these remains. A new study published at the beginning of October in the journal Current Biology analyzed the ancient DNA contained in these bones to determine which species they belonged to. The results show that while the majority of the remains come from cattle, bison, buffalo, and yaks, twenty genomes do not correspond to any known mammal. The scientists have attributed them to a new species, the X yak. The specimens would be cousins of modern yaks, which are now found on the high plateaus of the Himalayas and Tibet. The analysis of DNA showed that the X chromosome of mammals began to differentiate from that of modern yaks about 400,000 years ago. The lineage became a distinct species some 150,000 years later. "Given that it is a sister species to the Himalayan yak, sharing a common ancestor, it is reasonable to assume that they resembled each other," says Love Dalen, professor of genomics at Stockholm University. The most recent X yak genome recovered by the team dates back 27,000 years, and the oldest goes back 247,000 years. At that time, hominids also frequented the Denisova site, which suggests that these animals were in contact with our ancestors. "Although we do not have direct evidence of these interactions, it is likely that ancient humans, including Denisovans and Neanderthals, hunted the X yak during this period," says Jonas Oppenheimer, co-author of the study and researcher at Stockholm University. These new results highlight the role that the region may have played in the history of biodiversity and human settlement. "The Altai region has probably been a center of biodiversity and a potential refuge during the glacial cycles of the Pleistocene, as evidenced by the incredible diversity found there," concludes the scientist. The discovery of the X yak mainly reminds us that, long before the contemporary era, many animal lineages formed, whose secrets are still being revealed today.