Although the term "shamanic" is used to refer to a diverse range of phenomena, it nonetheless reflects something empirical. Cross-cultural research illustrates that the concept of the shaman reflects the existence of similar spiritual healing practices found in pre-modern foraging and simple horticultural and pastoral societies around the world (Winkelman, 1992; 2000). This cross-cultural concept of the shaman was initially proposed by the renowned scholar of comparative religion, Mircea Eliade (1964). However, his various characterizations of shamans were in part responsible for subsequent confusion regarding their exact nature and function. While offering very general characterizations of the shaman as someone who entered a state of "ecstasy" to interact with "spirits" on behalf of the community, Eliade also cited many additional specific concepts of the shaman which some subsequent researchers neglected in their applications of this term. This paper presents the findings of cross-cultural and crossspecies research that provides a basis for describing shamanism, its relationships to human nature, and its deep evolutionary origins. Shamanism has its bases in innate aspects of human cognition, engaging the use of altered states of consciousness to integrate information across several levels of the brain to produce visual symbolism exemplified in visionary experiences. The deeper evolutionary roots of shamanism are found in the capacities for ritual, which provide the most important communication and integrative processes in lower animal species. The evolution of shamanism can be deduced from these bases and the similarities of shamanic practices to the rituals of chimpanzees. Drumming, group vocalization, and other displays were the foundations from which the uniquely human mimetic capacity evolved and provided a basis for shamanism.