Armies are a purely human invention. Most soldiers who go to war nowadays don't even do it because they're inherently aggressive.
Frans de WaalYou should know as much as you can about the human species if you have a hand in designing human society. Of course, I'm not saying that you can derive moral rules from nature - that's deriving an ought from an is, as the philosophers say - but you do need to know what kind of animals we are if you want to design a stable society.
Frans de Waal