There are quiet a few theories why Humans developed the mental capacity we enjoy today. Some say it was the consumption of red meat. Some others the fact that we became bipedal and had to think on our feet.
Some others support the invention of cooking since it expanded massively the nutritional value of our food. And lastly, some support that getting stoned with psychedelic mushrooms might have done the trick.
As Humans began to migrate to new areas, at some point they came upon psychedelic mushrooms growing in cow droppings, as is their wont, and then ate them.
Homo sapiens ate our way to a higher Consciousness.
After ingesting them, and more specifically the psilocybin they contained, their brains kicked into overdrive, acquiring new information-processing capabilities, and a mind-blowing expansion of imagination.
The World never looks the same again after such an experience.
Psychodelic mushrooms and other mind altering substances have always been consumed by mammals, regardless of their sapien ancenstry. Animals do like to get stoned as much as Humans do.
200,000 years ago there was a sudden doubling of the Human brain. From an evolutionary point of view, that is an extraordinary expansion. And there is no explanation for this sudden increase in the brain.
Due to the desertification of the African continent Human forerunners were forced from the increasingly shrinking tropical canopy in search of new food sources.
They have been following large herds of wild cattle whose dung harbored the insects that were undoubtedly part of their new diet, and would have spotted and started eating magic mushrooms.
The effects of the mushrooms meant that the thought processes of Homo erectus rapidly reorganized and the effects of magic mushrooms played a pivotal role in the evolution of our species.
Increased clarity of vision makes hunting easier. Increased sexual desire means they were more prolific. At even higher doses the mushroom acted to dissolve boundaries, promoting community bonding and group sexual activities.
Consequently, there was a mixing of genes, greater genetic diversity, and a communal sense of responsibility for the group offspring. The Human-mushroom interspecies codependency was enhanced and deepened.
It was at this time that religious ritual, calendar making, and natural magic came into their own.
Psychedelic experience and other techniques, like dancing and music, were used by our early ancestors since to enhance Consciousness, which facilitated spirituality, art, and medicine.
Human evolution is complicated and for the most part it remains a mystery. There are simply way too many variables to take into account. A lucky gene mutation might have contributed to the expansion of our brains as much as a massive change in the ecosystem that somehow forced our ancestors to perceive things differently.