“…The dark cave environment combined with extended isolation from the outside world and disorientation may result in altered states of consciousness (Clottes and Lewis-Williams 1998;Freikman 2017;Lewis-Williams 2002a;Mlekuž 2019;Prijatelj and Skeates 2019;Sireteanu et al 2008), which originate within the nervous system, and thus are common to all humans, regardless of cultural differences. An ASC can be attained in many ways: by means of psychoactive drugs, intense concentration, hyperventilation, sustained rhythmic movement, food restriction, dehydration, sleep deprivation, meditation, and extreme environmental conditions, such as those in caves (Asaad and Shapiro 1986;Guerra-Doce, 2015a, 2015bHorowitz 1964;Kluver 1942;Lewis-Williams 1997;Morris 2006).…”