It would have made
much more sense if you put a bit more effort into trying to interpret what I said and didn't assume I think animal-eating was invented 200 years ago...
People certainly have a different emotional reaction from watching an animal die, this reaction being almost completely unknown those days, than from buying a hamburger in the supermarket, which doesn't provoke any emotion whatsoever. Do I have to convince you very much that emotions play a big role in the so called "morality" and especially being able to act on it?
Obviously there are historical examples that there were people a very long time ago already that were concerned about the sad fate of the killed animals, for example Native Americans used to "thank" the animals they killed for providing food and ask them for forgiveness, Buddhist say "might you be reborn as a buddha" before eating meat etc., you will see this aspect of human life very carefully regulated by most religions, indicating it was a problem that concerned people from a very long time ago.
For another, more general example, try to convince someone of sacrificing a very, very minor modern convenience of theirs for some greater good. I often have to go to terrible pains to explain that I am perfectly fine with my current phone and I don't want to waste it to just get a new toy, and I am far from being any kind of ecology freak. When I buy crips and coke at a grocery 50m from my flat and don't want a plastic bag, the seller assures me that it's for free so I don't have to worry :) The people who actually use any more substantial effort to not deprive too much resources are very often gravely ridiculed, because most of society seems to view resources as unlimited.