We would look at the caveman in this video and see him as an ignorant being who knows neither science nor technology. However, there is a theory that prehistoric humans did not have the sense of self or consciousness that modern humans have. They didn't have clocks or maps, they didn't know about the existence of linear time and space, and they had a different consciousness from modern people, where the left brain overwhelms the right brain. Therefore, they likely traveled easily to other worlds that modern humans only glimpse through the use of psychedelic drugs.