If you wanted a book about what "the new science of psychedelics" teaches us, this book is not for you. It's 1/3rd history, 1/3rd acid/mushroom trip memoir, and 1/3rd about the "science" of psychedelic therapy and consciousness. The first two parts are fun, but not really what I was looking for in an ostensibly serious book about the latest research on a interesting topic. I put science in scare quotes because the author basically just provides some refreshers on high school biology and lengthy accounts of interviews with scientists. However careful and guarded Pollan is through the book, he never really gets into the details of the studies: sample sizes, effect sizes, any meta-analyses that have been done, etc. It's typical popular science. The most useful part is the footnotes.