The ‘Intermission’ is the best and most definitive chapter of the book. I took away an insight, here, and an important nuance: religion, and specifically Christianity, is not a physical thing. And as an historical idea, it shouldn’t be, and can’t be, parsed using the same tools that we use for, say, genetics.
The book is well written but not light. Diamond weaves geography, climate, religion, and politics into a complex whole as he steps through several cultures to examine in detail what drove them to virtual extinction.
Darwin struggled with questions about mechanisms driving evolution and how they played out in the living, messy, world of nature.