We are all aware of the idea that plant-derived chemicals can have an impact on the functioning of the human brain. Most of us get a cup of coffee or tea in the morning, many of us sometimes eat some chocolate, some smoke a cigarette or take herbal supplements, and some people use illegal drugs. We know a lot about the mechanisms by which the psychotropic components of these different products affect the function of the human brain, but the question of why these effects have been almost completely ignored.

This book explains not only how, in terms of pharmacology or the science of psychotropic drugs, but more importantly why plant-derived chemicals and fungi have effects on the human brain. The answer to this latter question is, in part, in the forms of life in the terrestrial world, plants and insects, and the many ecological roles that "secondary metabolizing chemicals" try to play; for example, to defend plants against insectivores while attracting pollinators. The answer lies in the cross-genetic heritage of mammals, plants, insects and the sudden biological similarity between the three species.

In particular, it revolves around close correspondence between the brains of insects and humans, and signaling paths between cells that are common to plants and humans. Plants and the human brain describe how and why phytochemicals affect the function of the brain in relation to the three main groups of secondary metabolites: alkaloids, which provide us with caffeine, a group of toxins, a handful of hallucinations, and most drugs (eg morphine, cocaine, DMT, LSD And nicotine); phenols, including polyphenols, which are an important and beneficial part of our natural diet; and terpenes, a group of multifunctional compounds that provide us with active ingredients of hemp and many herbal extracts like ginseng, ginkgo and valerian..