200,000 years of evolution...

and there is: The law of war (also law of armed conflict, LOAC) is law concerning acceptable practices relating to war. In cases other than civil wars, it is considered an aspect of public international law (the law of nations).
http://en.wikipedia.org/wiki/Laws_of_war


great irony from Banksy on the Israeli West Bank barrier,
which I remembered watching the news this morning...
http://arts.guardian.co.uk/pictures/image/0,8543,-10405256016,00.html