There are actually a lot of people arguing that animal life is equivalent to human life.
See: http://en.wikipedia.org/wiki/Animal_liberation_movement
Richard Dawkins recently put up an interview he had with Peter Singer http://www.youtube.com/watch?v=GYYNY2oKVWU in 2008 about it which convinced me they are right but I still eat meat as I can't stand nearly all the vegan food I've tasted.