Suppose that we discover tomorrow that animals are not alone in feeling pain. Are plants then deserving of such consideration? What about bacteria? Fungi? Wher

Suppose that we discover tomorrow that animals are not alone in feeling pain. Are plants then deserving of such consideration? What about bacteria? Fungi? Where would we draw the line? Should we quit eating and die of starvation? It seems like there needs to be some acknowledgement that one form of life has to die in order that we may live. What gives us the right to declare that animals are the "higher" form of life simply because they're less alien than plants?