In his book Food of the Gods, McKenna proposed that the transformation from our early ancestors Homo erectus to the species Homo sapiens mainly had to do with the addition of the mushroom Psilocybe cubensis in out diet – an event which according to his theory took place in about 100,000 BC (this is when he believed that our species diverged from the Homo genus). He based his theory on the main effects, or alleged effects, produced by the mushroom. One of the effects that comes about from the ingestion of low doses, which agrees with one of scientist Roland Fischer’s findings from the late 60s-early 70s, is it significantly improves the visual acuity of humans – so theoretically, of other human-like mammals too. According to McKenna, this effect would have definitely prove to be of evolutionary advantage to our omnivorous hunter-gatherer ancestors that would have stumbled upon it “accidentally”; as it would make it easier for them to hunt.
In higher doses, McKenna claims, the mushroom acts as a sexual stimulator, which would make it even more beneficial evolutionary, as it would result in more offspring. At even higher doses, the mushroom would have acted to “dissolve boundaries”, which would have promoted community-bonding and group sexual activities-that would result in a mixing of genes and therefore greater genetic diversity.