I am usually proud to announce in any social setting, whenever there's a discussion of this sort, that I am anti-violence and anti-war. I usually get the phrase that irritates me: "violence is in our animal nature, you can't get rid of it!", and I strongly disagree.
Actually, few contradicting arguments are always cited for justifying many issues. The pop-song among which is "man is the only violent being, nothing in nature does what man does". Many embrace what it implies at face value, but when confronted they change their stance and claim they know it's untrue, like a pop song. The acts of violence that exist in other life forms are staggering, for example, many think corals are a thing of beauty and natural harmony supporting a complete ecosystem, in fact they fight for territory just like every other species we observe. When two corals fight, they extrude their stomachs and digest the rival coral, alive. That is violent.
When we observe the animal kingdom, there are proven cases of homosexuality. It exists among dolphins, cats, chimps, penguins, and even worms. Often the argument against gay people is that what they do is unnatural. Confront them with the fact that it exists in nature widely and that genetic research is finding that many gay people are gay by their nature, they reject the entire argument because they believe that we simply are above animals because we control our behavior.
Which is it, are we violent animals? Or are we outside the animal kingdom and no pattern in their world could apply to us? There's a podcast I listened to a while back by Radiolab titled New Normal discusses this very topic. They observed a family of baboons in Kenya that lived in violence to control territory over food, and when a tourist lodge was erected nearby, food leftovers were abundant and the violence grew because every baboon in the area wanted in on the bounty. But after a sickness spread, the majority of the "alpha" male baboons died. This epidemic in this community caused a new order of "anti-violence". The violence was gone and the battles between males were replaced by a humane and caring "nature".
There's an interesting article on Scientific American on Obama's statement that war started with the first man. Obama is for sure a very intelligent man and might very well know it isn't entirely true, but he's a politician. I think he simply cannot not justify ongoing violence that many stakeholders are involved in, the bounty is just too much to let go of now.