Research into ancient DNA has revealed that the ancestors of the modern European bison were the result of a hybridisation event over 120,000 years ago, but the first clues of this species were recorded on a cave wall 15,000 years ago.
An international team led by the Australian Centre for Ancient DNA (ACAD) studied ancient DNA extracted from radiocarbon-dated bones and teeth found in caves across Europe, the Ural mountains and the Caucasus mountains. They discovered genetic signals in many fossil bison bones that were distinctive from the European bison of the time and other known species.
This newly discovered species is currently named “Higgs Bison” in the research published in Nature Communications, due to its elusive history.
“Finding that a hybridisation event led to a completely new species was a real surprise – as this isn’t really meant to happen in mammals,” says study leader professor Alan Cooper, ACAD Director. “The genetic signals from the ancient bison bones were very odd but we weren’t quite sure a species really existed – so we referred to it as the Higgs Bison.”
The genetic data suggest that the Higgs Bison was the result of cross-breeding between the extinct Aurochs, the ancestor of cattle, and the Ice Age Steppe Bison.
The dated bones also suggest that the Higgs Bison took turns with the Ice Age Steppe Bison as the top species, a fact that our Magdalenian period hunter ancestors also recognised.
“The dated bones revealed that our new species and the Steppe Bison swapped dominance several times, in concert with major environmental changes caused by climate change,” says lead author Dr Julien Soubrier. “When asked, French cave researchers told us that there were indeed two distinct forms of bison art in Ice Age caves, and it turns out their ages match with those of the different species. We’d never have guessed the cave artists had helpfully painted pictures of both species for us.”
The variants of these cave paintings had either long horns and large forequarters or shorter horns with small humps. These no doubt masterpieces of the time resemble the modern American bison and European bison respectively.
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“Once formed, the new hybrid species seems to have successfully carved out a niche on the landscape, and kept to itself genetically,” says Professor Cooper. “It dominated during colder tundra-like periods, without warm summers, and was the largest European species to survive the megafaunal extinctions.
The modern European bison was hunted to extinction in the wild in the early 20th century, but has since been reintroduced to wild forests in Europe, most notably the Białowieża Forest on the border between Poland and Belarus, through captive breeding from just 12 individuals. This genetic bottleneck is likely one of the reasons the ancient form bears little resemblance to its descendants.