"If the experimenter would not be prepared to use a human infant, then his readiness to use non-human animals reveals an unjustified form of discrimination on the basis of species, since adult apes, monkeys, dogs, cats, rats and other mammals are more aware of what is happening to them, more self-directing and, so far as we can tell, at least as sensitive to pain as a human infant."
Animal Rights FAQ
The End of Suffering?
The Post-Darwinian Transition
Reasons to be Vegetarian (video)