Capra is a genus of mammals, the goats or wild goats, composed of up to nine species, including the wild goat, the markhor, and several species known as ibex. The domestic goat (Capra aegagrus hircus) is a domesticated subspecies of the wild goat (Capra aegagrus). Evidence of goat domestication dates back more than 8,500 years. Wild goats are animals of mountain habitats. They are very agile and hardy, able to climb on bare rock and survive on sparse vegetation. They can be distinguished from the genus Ovis, which includes sheep, by the presence of scent glands close to the feet, in the groin, and in front of the eyes, and the absence of other facial glands, and by the presence of a beard in the males, and of hairless calluses on the knees of the forelegs. The Rocky Mountain goat is in a separate genus, Oreamnos.