Tale as old as time, frankly. Someone creates a surplus, another wants that surplus for himself. First we have warring tribes. Then we have warring cities. Then

Tale as old as time, frankly. Someone creates a surplus, another wants that surplus for himself. First we have warring tribes. Then we have warring cities. Then we have warring kings. Then we have warring nations. Then we have warring empires. Throughout we have various forms of serfdom/slavery/etc. when there's not enough war. Then we have colonialism, or in Joseph Conrad's words "civilized pillaging and raping." Today we have capitalism, or just colonialism without the raping. Monkey see, monkey want, monkey kill and brutalize to get. If animals could make full use of their environments, I'm sure they would be greedy too. It's just an innate part of living things.