Genomic back-breeding returns extinct “supercow” to Europe

January 12, 2017

Described as “mighty beasts that stood almost as tall as elephants, with lean, powerful frames and fearsome horns,” the earliest form of cows did not look much like the cows of today. Known as aurochs, these animals were the largest land mammals in Europe, until the rise of human civilization decimated their numbers. Records shows the last of the species died in Poland in 1627 — one of the first recorded cases of extinction.

But now, thanks to ecologist Ronald Goderie, a "near 100% substitute" of the beast is returning to the forests. This is being made possible by the Tauros program, a project launched in 2008 to address failing ecosystems.

The most powerful herbivore in European history seemed to offer a solution as conservationists believe the loss of the keystone herbivore was tragic for biodiversity in Europe. Researchers say that the aurochs' huge appetite for grazing provided a natural "gardening service" that maintained landscapes and created the conditions for other species to thrive.

To do this, Goderie chose a method known as back-breeding to create a substitute bovine he named "Tauros." This was possible because auroch genes remain present in various breeds of cattle around the continent, and the team identified descendants in Spain, Portugal, Italy and the Balkans. Geneticists advised breeding certain species together to produce offspring closer to the qualities of an auroch, and then breed the offspring.

The animals get closer with each generation. The team has the advantage of being able to test the offspring's DNA against the complete genome of an auroch, which was successfully sequenced at University College Dublin.

"You could see from the first generation that apart from the horn size, there was enough wild in the breed to produce animals far closer to the auroch than we would have expected," Goderie said in the article.

The ecologist had predicted that seven generations would be necessary for the desired outcome, which might be achieved by 2025. Now in its fourth generation, the article explains, pilot schemes across Europe are offering encouragement.

Using protected land in Croatia, Spain, Portugal, the Czech Republic, and Romania, Goderie's cross-breeds could test themselves in the wild, and in many cases they rose to the challenge.

"We see progress not only in looks and behavior but also in de-domestication of the animals," Goderie said. This is a challenging process as they have to adapt to the presence of large packs of wolves —particularly at the Croatian site. However, Goderie added that the Tauros have learned to defend themselves and suffered few losses.

While selective breeding will continue toward creating the ideal animal, the current crop is already serving a function as landscapes in dire need of grazing animals are starting to make a comeback.

"Without grazing everything becomes forest, or barren land when there is agriculture," said Frans Schepers, managing director of Rewilding Europe. "The gradients in between are so important for biodiversity, from open soil to grassland and 'mosaic landscapes.'"

However, critics of rewilding initiatives have suggested that introducing new species could have unintended consequences. The International Union for the Conservation of Nature (IUCN) has issued new guidelines in an effort to manage such impacts.

"Bringing back close approximations of original species may help to reverse losses from emotional to ecological grounds, but often the devil lies in the detail," said Dr. Axel Moehrenschlager, IUCN Chair of the Reintroduction Specialist Group.

The article explains some questions raised are whether primarily wetland forests like the aurochs used to inhabit still exist, whether it could negatively impact wild or domestic plants or animals, and if it might endanger people.

The successful introduction of bison in the U.S. shows that such initiatives can have a positive impact, said Dr. Eric Dinerstein, but he adds that one intervention can lead to another.

"If an ecosystem evolved with large herbivores...there is not an alternative and you need something in its functional role," he says. "But to introduce aurochs, you may need predators as well."

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