Life eats life to live. Creatures all the time are domesticating each other, it is the process of symbiosis, parasitism, that's one of life's defining features. mothers give birth to varied children in overabundance as experiments in this grand evolutionary game. delicately crafted creatures that we in no way are capable of crafting ourselves are just food in the scheme of things. our intensely strong consciousness of our very being, personality, individuality , our attachment to this strong sense of self, to the personality of others, these are also part of our mortal animal nature.
this is all very hard for us very conscious clinging to ego beings to take. it has always made it hard for us to take part in this cycling of life on earth. can we choose to take ourselves out of this pattern and not eat animals? i think for some that is a possible route if taking the life of animals causes them personal pain.
however even if 6billion humans become vegetarian, this is not a life of do no harm. we have to deny billions of other animals the right to their own vegetable food, room to live, not to mention the incredible burdens we put on ecosystems as a whole.
one day we will have to come to terms with the fact that we are life, and this is the way life is, it is not a mamby pamby fairy existence. life is gutsy and intricately intertwined with suffering and death. the only way out of this reality is to take the poison koolaid and believe your soul is going to live on some passing comet. (in fact it is this tendency to shy from the horrific reality of life and try to fly away to an idea of an eternal soul in heaven that i find one of the most dangerous aspects of many religions)
The bhagavad Gita has an interesting view on this. Arjuna is a warrior preparing to bring his army to battle. he is standing on a mountain watching both armies prepare. the sight overwhelms him, he begins to imagine all the death and suffering his soldiers will cause, and the families that will suffer when their soldier-fathers don't come back from battle, and... he freezes.
So Krishna comes and takes the whole rest of the book convincing him that there is no other way. if his army does not fight then the enemy army will also cause suffering to his people. Krisha brings him to the very pinnacle of experience of the horrific reality of life with its whirling giant maw of teeth and arms and eyes of creativity through destruction (for that is what the evolutionary process of life on this earth as been for the past 3.6billion years that has produced the myriad crafted beings we are and share this life with) and then brings him back down to his reality, he is a warrior and his role is too fight.
if i worried about every tiny ant i might step on, every animal who suffers in order for my crops to grow, if i worry about every person i may harm in my inept attempts at human interaction, if i worry about every chemical and machine and genetic defect out there that might cause me harm and shorter life, id never get out of the house and live. that is not the way. i was created part of this vast living couldron, and i choose to partake in it.
that's what eating animals is about.