Monoculture is the single most powerful simplification of modern agriculture, the key move in reconfiguring nature as a machine, yet nothing else in … - Michael Pollan

Design in nature is but a concatenation of accidents, culled by natural selection until the result is so beautiful or effective as to seem a miracle of purpose.

Beauty and nature often shows up in the vicinity of sex—think of the plumage of birds or mating rituals through out the animal kingdom. “Sexual selection”—that is, evolution’s favoring of features that increase a plant’s or animal’s attractiveness and therefore it's reproductive success—is the best explanation we have for the otherwise senseless extravagance of feathers and flowers, maybe also sports cars and bikinis. In nature, at least, the expense of beauty is usually paid for by sex.
There may or may not be a correlation between the beautiful and the good, but there probably is one between beauty and health. (Which, I suppose, in Darwinian terms, is the good.) Evolutionary biologists believe that in many creatures beauty is a reliable indicator of health, and therefore a perfectly sensible way to choose one mate over another. Gorgeous plumage, lustrous hair, symmetrical features are “certificates of health,” as one scientist puts it, advertisements that a creature carries genes for resistance to parasites and is not otherwise under stress. A fabulous tail is a metabolic extravagance only the healthy can afford.

The images and words brought back from these journeys—visits with the souls of the dead and unborn, visions of the afterlife, answers to life's questions—were powerful enough to compel belief in a spirit world and, in some cases, to serve as the foundation of whole religions. Of course, plant drugs are not the only technologies of religious ecstasy; fasting, meditation, and hypnotic trances can achieve similar results. But often these techniques have been used to explore spiritual territory first blazed by the entheogens.
What a natural history of religion would show is that the human experience of the divine has deep roots in psychoactive plants and fungi. (Karl Marx may have gotten it backward when he called religion the opiate of the people.)