The "stoned ape theory" is a hypothesis proposed by Terence McKenna in the 1990s that suggests that the use of psychoactive mushrooms by early humans was a key factor in the evolution of human consciousness. According to the theory, early humans who consumed psychoactive mushrooms would have had enhanced cognitive abilities and increased ability to communicate, which would have led to the development of human culture and civilization.
However, there is currently no scientific evidence to support the stoned ape theory. While the consumption of psychoactive substances by early humans cannot be ruled out, there is no concrete evidence that suggests that it played a significant role in human evolution. Additionally, there are many other factors that have been proposed as contributing to the development of human consciousness, such as the development of language, tool-making, and the expansion of the brain.
It should be noted that the stoned ape theory is considered a fringe theory and is not widely accepted by mainstream scientists and researchers. Also, there is no scientific evidence that consumption of psychoactive mushrooms leads to cognitive enhancement or increase of communication abilities. Therefore, further research is needed to determine the validity of the stoned ape theory and its potential impact on human evolution.