The European bison (Bison bonasus), also known as wisent or the European wood bison, is a Eurasian species of bison. It is one of two extant species of bison, alongside the American bison. Three subspecies existed in the recent past, but only one survives today. The species is, theoretically, descended from a hybrid, a cross between a female aurochs, the extinct wild ancestor of modern cattle, and a male Steppe bison; the possible hybrid is referred to informally as the Higgs bison. Alternatively, the Pleistocene woodland bison has been suggested as the ancestor to the species.