What single difference could account for the vast gap between us and chimps when we're so genetically close, ninety eight point something percent? How did we end up this different? His answer is a different idea of human cognition: shared intentionality, the uniquely human ability to understand others as intentional agents like yourself and to share attention and goals with them, to point at something just to share it, to say "look at that, together."

I'd expected a gray, impenetrable monograph, but it isn't. The writing of the book is very good, accessible, and articulates its theories clearly. It does this without leaning too much on technical jargon, making it very easy to read, and it is full of examples and references.

The strong claims about apes and his heavy emphasis on "theory of mind"-type approaches to understanding social cognition haven't aged particularly well. The parts where I know the source literature are deeply problematic, given contemporary interpretations of those results, and, tellingly, many of the researchers he cites have since changed their views on some of those findings. So you're reading experiments whose own authors now interpret differently. In fairness, there is only so much criticism one can direct at Tomasello, since many of these objections largely did not exist when he was writing the book.