Ethics and Eating Meat

When people eat what their community eats they are moral... When they put themselves outside of their communities, or above others by choice, they are immoral... And this goes for all behavior...

It seems logical that humans have been eating meat for as long as the food chain has existed. But the modern world seems to be built upon justifications for everything it does and thus something there must be some sort of human justification as to why we kill other living things for our own sustenance seems ethically challenged.

If I were to read this justification in a book like some famous person saying that it is okay to eat meat because they say it is okay then maybe I might believe them.

Was it Constantine who declared that meat was to be eaten by everyone everywhere or maybe it was Charlemagne?

Perhaps it is older? (perhaps i made that up) It is hard to believe that civilization has some things to wrestle with on their conscience and someone has not addressed it.

What would be the rationale? That animals were put here for us to eat?

It seems probable that bio mass will one day be farmed and slaying animals will not be necessary to sustain human life.

But as for today life seems dismal especially if you are unlucky enough to be born into this world as a cow or a chicken.