Regarding your point about a God giving us animals, all major
religions regardless of whether they allow you to eat them 
forbid cruelty to them. It would therefore contradict religion 
to condone factory farming by eating the products of this 
'inhumane' method. As your clearly not religious or familiar
with any religious book i'll move on. Evolution would also side 
with leaving off the abusing and killing of animals as with 
evolution comes higher morality and deeper more widespread 
compassion. I find it perplexing that you would mention cave-
paintings as they are an example of our backwards, un-evolved 
ancesters, their certainly not an example to follow. Theres a 
cave painting of a man with an elk! and he's not hunting it!!! 
 Meat is incredibly bad for your health you would have to be 
taking the piss to say otherwise, but if you wish to debate it 
then i'm game!!! As for whether we're designed for it then that 
is highly questionable aswell.