The aurochs was the wild ancestor of modern cattle. With large horns and great strength, it inspired awe and fear until it went extinct in 1627. After a failed attempt to resurrect the aurochs in the 1930s, a new generation of biologists has been trying to back-breed a replica by combining traits from various heritage cattle. They hope that analysis of ancient DNA from fossilized aurochs will help guide and speed up the process. Already they are establishing herds of aurochs like cattle in various countries as part of an ambitious effort to rewild abandoned farmland and nature reserves in Europe.