Among the Ju'hoansi, San hunter-gatherers of the Kalahari Desert in present-day Namibia and Botswana, num (often written n/om) is described as a healing potency that skilled practitioners, n/om kxaosi ("owners of num"), learn to activate and control within their own bodies, chiefly during the all-night communal healing dance that remains a regular feature of Ju'hoansi social life rather than an occasional emergency ritual. During the dance, women sit in a circle around a fire, singing and clapping specific medicine songs, while n/om kxaosi dance around them in a circle for hours, building heat that practitioners describe as num "boiling" up from its resting place at the base of the spine.
As num rises and intensifies, the dancer enters kia, a state of heightened perception and altered consciousness, at which point the healer is understood to be able to see sickness within community members and draw it out, often through touch, trembling and a cry believed to expel the extracted illness. Richard Katz's detailed ethnographic study, Boiling Energy: Community Healing among the Kalahari Kung, documents the dance as an egalitarian institution: num is described as potentially available to any adult willing to undertake the demanding, sometimes frightening training needed to control it safely, rather than restricted to an inherited priestly class.