Do animals have a moral sense? I believe we seriously underestimate the sentience and mental capacities of most animals, so I welcome a book such as this, which challenges our anthropocentric prejudices. By making us think, it does a valuable service in raising our awareness.
The thesis seems sensible, that our own ethical sense might not have sprung fully formed out of nowhere, but have evolutionary antecedents in the animal world, especially among highly social animals. This is backed by experimental work described in the book, and numerous anecdotal observations in the wild, such as the mature female elephant who fended off an attack on a hurt female elephant by a younger male, and seemed to tend her wounds with her trunk, or the mouse who feeds and fetches water for another trapped and injured mouse.
However, it was when I tried to find references for some of the experiments that I began to get more skeptical. One that is oft quoted in the book, and echoed widely on the Internet is the alleged experiment where a hungry rat refuses to press a lever to get food, once he realises it causes another rat to receive an electric shock. No references are given in the book, nor in any of the sources quoting this experiment, and I cannot find any information as to the original published experiment. Is it just heresay? Other experiments are referenced, but raise further questions, such as the rat who first releases another caged rat, rather than obtain a piece of chocolate. Were they related, or mates, or total strangers? Were the rats naive or had they done this many times? How had they learned to obtain the chocolate or release the cage door?
The style of narration is clear, somewhat stentorian, and serious, and this is the nub for me. This is a book with a message, a manifesto, who's aim is to convince. What it lacks as a scientific work is a willingness to critique the evidence or search for other explanations than the thesis put forward. However, if it brings the end of inhumane animal experiments a day closer, it will have been worthwhile.