We are a fine species with some potential. Yet we are racked by sickening amounts of violence. Unless we are hermints, we feel the threat of it, ofte… - Robert Sapolsky

Ecosystems majorly shape culture — but then that culture can be exported and persist in radically different places for millennia. Stated most straightforwardly, most of earth’s humans have inherited their beliefs about the nature of birth and death and everything in between and thereafter from preliterate Middle Eastern pastoralists.

In the 1930s an anthropologist named Paul Radin first described it as "shamans being half mad," shamans being "healed madmen." This fits exactly. It's the shamans who are moving separate from everyone else, living alone, who talk with the dead, who speak in tongues, who go out with the full moon and turn into a hyena overnight, and that sort of stuff. It's the shamans who have all this metamagical thinking. When you look at traditional human society, they all have shamans. What's very clear, though, is they all have a limit on the number of shamans. That is this classic sort of balanced selection of evolution. There is a need for this subtype — but not too many. The critical thing with schizotypal shamanism is, it is not uncontrolled the way it is in the schizophrenic. This is not somebody babbling in tongues all the time in the middle of the hunt. This is someone babbling during the right ceremony. This is not somebody hearing voices all the time, this is somebody hearing voices only at the right point. It's a milder, more controlled version. Shamans are not evolutionarily unfit. Shamans are not leaving fewer copies of their genes. These are some of the most powerful, honored members of society. This is where the selection is coming from. … In order to have a couple of shamans on hand in your group, you're willing to put up with the occasional third cousin who's schizophrenic.

We're only a couple of hundreds of years into understanding that epilepsy is a neurological disease and not a demonic possession. We're only about 50 years into understanding that certain types of learning disabilities are micro malformations in the cortex in people with dyslexia and not laziness or lack of motivation. The vast majority of these factoids [presented in the book] are 10, 20 years old, and all that's gonna happen is we're gonna learn more and more of that stuff. And what we're going to learn more and more is to recognise extents to which we're biological organisms and our behaviours have to be evaluated in that realm. For my money, what that eventually does is make words like "soul" or "evil" utterly absurd and medieval, but it also makes words like "punishment" or "justice" very questionable, as well. I think it will require an enormous reshaping of how we think we deal with the most damaging of human behaviours, because none of it can be thought of outside the context of biology.