Thanks! In addition to evolution, it's been fun (and useful) to think about the ethics material again. Got fired up in grad school where the veterinary library held a comprehensive collection of relevant books. (At the time, the veterinary faculty was especially vocal in their support of animal experimentation, so maintaining this collection was very much to their credit.) Read all of them instead of finishing thesis - and was soon shown the door! @OldNewbie's post above brought to mind Raymond G. Frey, author of The Case Against Animals. Frey's work is a good example of just how difficult it is to refute animal liberation/animal rights. He devised a convoluted, counter-intuitive argument based on specific cognitive requirements he claimed were needed in order to be eligible for moral consideration. Ultimately, he rejected many of his own conclusions. Surprisingly, these ideas are rarely discussed among professional advocates these days, IME. Just last week, had to gently edit a colleague's work because it emphasized sparing dogs in a particular type of experiment, to the exclusion of rats, who are used far more frequently.