" Indeed, the proposition that humans have mental characteristics wholly absent in animals confounds the theory of evolution, which, although disputed by some religious extremists, is generally accepted by most educated people throughout the world. Charles Darwin made quite clear that there are no uniquely human characteristics when he wrote that "the difference in mind between man and the higher animals, great as it is, is certainly one of degree and not one of kind. "

― Gary L. Francione , Introduction to Animal Rights: Your Child or the Dog?