Different forms of shamanism are found around the world, and are also known as medicine men and witch doctors. It has beem especially common among circumpolar peoples; in Old Norse Religion[?], however, shamanism was seen as un-manly and practiced mainly by women (although in Old Norse mythology, the supreme god Odin was also seen as the supreme shaman).
Shamanism is based on the belief that the visible world is pervaded by invisible forces or spirits that affect the lives of the living. In contrast to animism and animatism, which any and usually all members of a society practice, shamanism requires specialized knowledge or abilities. Shamans are not, however, organized into full-time ritual or spiritual associations, as are priests.
Shamans enter into trances, either autohypnotically[?] or through the use of hallucinogens, during which time they are said to be in contact with the spirit world. In some societies shamanic powers are inherited. In others, shamans are "called:" Among the Siberian Chukchee[?] one may behave in ways that Western clinicians would characterize as psychotic, but which they interpret as possession by a spirit who demands that one assume the shamanic vocation. Among the South American Tapirape[?] shamans are called in their dreams. In yet other societies shamans choose their career: Indians of the Plains would seek communion with spirits through a "vision quest;" South American Shuar[?], seeking the power to defend their family against enemies, apprentice themselves to accomplished shamans. Shamans often observe special fasts and taboos particular to their vocation. Oftentimes the shaman has, or acquires, one or more familiars, usually spirits in animal form, or (sometimes) of departed shamans.
Shamans can manipulate these spirits to diagnose and cure victims of witchcraft. Some societies distinguish shamans who cure from sorcerers who harm; others believe that all shamans have the power to both cure and kill; that is, shamans are in some societies also witches. The shaman usually enjoys great power and prestige in the community but may also be suspected of harming others and thus feared. Most shamans are men, but there are societies in which women may be shamans (in Old Norse culture, as mentioned above, only women; for men to practice shamanism was shameful). In some societies the male shaman denies his own sexual identity by assuming the dress and attributes of a woman; this practice is rare but has been found among the Chukchee, Sea Dyak[?], Patagonians[?], Aruacanians[?], Arapaho, Cheyenne, and Ute.