What is the theme in Food of the Gods: The Search for the Original Tree of Knowledge by Terence McKenna?

McKenna argues that we are what we eat, but in a radically different sense. Plants play a role in mediating human culture and relationships. Not only do foods elicit specific emotional responses and behaviors, but they have also been found to contain medicinal properties.

It may be no coincidence that the neurotransmitters in the brain are very similar to the chemical structure of the indole hallucinogens found in psychoactive plants such as mushrooms. This similarity suggests a close relationship wherein the plant may easily become a part of the human and influence them in a multitude of ways.