This was because he began to feel a great disjunction between what [he] had learned as a social anthropology student and the then popular conception of San rock art as a childlike record of daily life with, perhaps, a few 'mythical' images thrown into the mix.

Using Maurice Godelier's ideas of symbolic work, Lewis-Williams investigated the ritual role of shamans in terms of San social structure and the context of rock art.

As an undergraduate he was exposed to Isaac Schapera's The Khoisan Peoples of South Africa (1930)[6] From the start of his professional career he drew on ethnography to address the meaning of San rock art.

In 1968, he read philologist Wilhelm Bleek and his sister-in-law Lucy Lloyd's Specimens of Bushman Folklore,[2] and later engaged with the manuscripts the archive of transcriptions of conversations with ǀXam-speaking San people from the 1870s.

[2] The 'trance dance, as practised by the Juǀʼhoansi in Botswana and Namibia in the twentieth century, has been at the centre of Lewis-Williams' arguments about shamanism and altered states of consciousness as the source of the images seen in southern African rock art.

However, several researchers (including the artist Pippa Skotnes, the literary scholar Michael Wessels and the archaeologist Anne Solomon) dispute Lewis-Williams's interpretation of the important ǀXam San ethnographic texts that describe dances and healing[14] Shamanism, which derives from the Siberian Tungus word shaman, was used by Lewis-Williams to explain the metaphor of death that he alleges is common to both ethnography and San rock art.

Features depicted in images that, it is argued, relate to altered states of consciousness, include nasal bleeding and the ‘arms back’ posture.

[17] Building on the work of previous scholars such as Lorna Marshall and Daniel McCall regarding a 'pan-San' belief system,[18] Biesele and Lewis-Williams together suggested that the conceptual linguistic terms and ritual observances similar to the Juǀʼhoansi and ǀXam could be used to understand the complexity of the images.

Together with Thomas Dowson, Lewis-Williams explored the relationship between universal neuropsychological patterns in the wiring of the human brain and practices in shamanistic societies.

[20] Using data produced from laboratory experiments with hallucinogens, they proposed a neuropsychological model with multiple stages of hallucinations experienced during altered states of consciousness.

Despite being able to explain why geometric and representational forms occur together in much hunter-gatherer art worldwide, and providing a 'universal' link through human neurology if cultural differences are allowed, the model has been criticised.

In 1972, he met André Leroi-Gourhan (a French prehistoric archaeologist who worked on Upper Palaeolithic rock art) at a conference in Valcamonica, Italy.