[fireant]

Is this what the whole argument about intelligence is about? That you don't want to cause suffering and only species of certain intelligence can suffer and others can't, thus you are not feeling guilt when killing and eating things that are not intelligent?

That just seems so bizarrely naive to me. Every living thing suffers when hurt. Suffering is a feeling of not wanting to die, or to be hurt. I'm pretty sure that it is one of the primary mechanisms of evolution of living things, it is a strive for self preservation. Human suffering is fundamentally the same as that of an octopus, an insect or a tree.