it depends on which animals you mean.
there are animals who are self aware. we
don't know what level of thinking they do.
they do have some language, just not as
sophisticated as our own. they certainly
can feel pain and do suffer. the reason
we do it is because we can. we have power
over them and we feel we are superior and
that human needs and wants are more
important than animal welfare. same
reason we eat them. it's not pretty or
nice but i think that's what it boils down
to. humans suck! lol.