Ritual alterations of consciousness are a virtual universal of human cultures, reflecting a basic human drive generally considered of central importance to religion and spiritual practices. Cross-cultural perspectives show both similarities in the experiences of altered consciousness (AC) that implicate biological factors as the basis for similarities across cultures, time, and space, as well as
... [Show full abstract] cultural differences in the manifestations of these potentials that implicate social factors. Individual and group experiences of altered consciousness may vary in many ways, but it is commonal-ities and recurrent patterns, rather than unique differences, that are crucial to understanding AC. This introduction reviews evidence for the universal manifestation of altered consciousness. This universal manifestation is not well explained in the classic paradigms of altered states of consciousness that emphasize their individual nature. In contrast, a biological approach to consciousness helps to situate altered consciousness within human nature. This perspective provides a foundation for an approach that characterizes AC in terms of an integrative mode of consciousness that reflects systemic features of brain functioning. This integrative mode of consciousness is typified in theta wave patterns that synchronize the frontal cortex with discharges from lower brain structures. This integration of ancient brain functions into the frontal cortex explains many of the key features of AC.