There's so much talk about the nature of intelligence today, and it's here that this book offers an essential contribution on the nature of ourselves relative to our fellow animals and how we value different abilities. Rather than seeing other species as completely different than ourselves, de Waal convincingly argues, with numerous experiments, that our different abilities are rather a matter of degree. He charts the fascinating history of ethology, and how the initial impulse to ascribe meaning to the behavior of other animals quickly became taboo until quite recently, and how that lens can help us understand how we treat and reason about other organisms. Highly recommend.