Llamas have been domesticated since the early days of Incan civilization and no longer appear in the wild. The animals are useful to humans in a variety of ways, but are primarily utilized as pack animals in the Andes Mountains. Llamas are well equipped for such a role due to their typically gentle nature, stamina, tolerance for high altitudes, diminutive need for water, and diverse diet. When they are overburdened or mistreated, however, llamas stubbornly refuse to budge and may kick, hiss, and spit. In addition to use as a transport animal, llamas are sometimes raised as a source of meat, milk, hides, and wool.