<< The basic idea seems to be that psychotropic substances led to faster
memetic evolution, which in turn led to exploration of different ways
of interacting and seeing the world. His problem is to show
that this actually took place.
There is a picture a dancing person with mushrooms sprouting all over their
body in the tassili plateau in northern africa dated (4000 BC? 6000?), so
there were definatley cultures taking them near where primates evolved into