This was outstanding. Really, really interesting. Woods, who was primarily interested in chimpanzees, goes to a bonobo sanctuary in the Congo with her fiance, and for several years they study the apes there. The basic idea is that bonobos are intensely peaceful, cooperative, and tolerant animals... which makes them very unlike chimps, and very unlike humans - and if there's a place in the world where human violence and cruelty is on full display, the Congo is it. (Fair warning: the book is scattered with truly hideous stories from the war there.) Woods' partner Brian wants to isolate what makes bonobos different from the other apes, as part of an effort to understand in turn the nature of (closely-related) humanity. The experiments the two of them carry out - for example trying to see if bonobos will cooperate with each other to solve puzzles for green apples, their favourite food - are interesting and well described, clearly illustrating the personalities and behaviour of the animals.

It's an often sad and often horrifying book, but there's a fundamental hopefulness there, both for the conservation efforts keeping the endangered bonobo alive, and for the positive influence they might have on a species that sorely needs it.