The Denisova Cave, and the Altai Mountains on which it is located, are one of the most important fossiliferous sites in the world, especially for the evolution of our species: it is here that, almost twenty years ago, those of a new species of man, announced in 2010 and whose taxonomy is still being discussed today, were discovered, together with the remains of some Neanderthals.
But Denisova also hides other secrets: as announced in a study published on Current Biologya collaboration between Stockholm University and the Swedish Museum of Natural History has made it possible to find the bones of an extinct yak, belonging to a still unknown species and baptized simply, pending the official Latin name, Yak X.
From bones to DNA
The bones from which the new yak species was identified were so-called “non-diagnostic bones”, too small and incomplete to allow identification of the species to which they belonged. To overcome this limitation, the researchers extracted DNA from the bones and managed to sequence 20 different genomes, the oldest of which dates back almost 250,000 years and the most recent 27,000. A comparison between these genomes and those of modern yaks, and other related cattle, made it possible to identify the species as new and still unknown.
The new yak does not yet have an official scientific name: for the moment it is known only as Yak X. According to the team, Yak These times are important: 400,000 years ago is also the time when brown bears and polar bears began to separate; it was “a particularly warm period, which led to the separation of populations and speciation”, according to Alexandre Gilardet, one of the authors.
Why doesn’t Yak X have a name?
The remains of the new yak also allowed us to discover other details about the species. For example, unlike what the humans who lived in Denisova Cave did, these cattle did not hybridize with other similar species, for example the steppe bison or the aurochs.
A consequence of this genetic isolation is that, when temperatures rose again 120,000 years ago, Yak X, which was a cold-adapted species, began to decline, replaced by other, more adapted species; the authors estimate that it became definitively extinct around 27,000 years ago.
Finally, in case you were wondering, there is a reason why Yak
The next step for the researchers will therefore be to look for new remains, and to re-analyse bones already found and generically classified as “belonging to some species of yak”.
