We all have stories of pets or other animals doing things that seem like they could only be the result of thought or emotion. Yet, the idea of animal intelligence has long been dismissed or discounted. Now, a growing number of scientists are trying to rigorously study how animals' minds work, and finding that sometimes our own brains get in the way. Primatologist Frans de Waal chronicles the history of the scientific community's shifting attitudes toward animal intelligence in his new book, Are