For me for example its “Eat me - a natural and unnatural history of cannibalism” by Bill Schutt. Its an amazing book that covers cannibalism in animals and then the history of it in humans (cultural, survival & medicinal cannibalism).
I got a lot of “oh why would someone read something like that?” And “that not something fun to read about!” From relatives but my friends enjoyed the stuff that I could tell them about cannibalism!
Don’t Sleep, There Are Snakes by Daniel Everett. It’s about a Christian missionary who goes to try to convert members of the Pirahã tribe in the Amazon, and he ends up losing his faith in God and becoming obsessed with linguistics instead. The Pirahã language and culture are fascinating. They have no counting system, no fixed terms for color, no concept of war, and no personal property. I read this after State of Wonder by Ann Patchett. Loved both books.