We have just gotten better at protecting lives from deaths.
Yes, but humanity has also gotten better at causing death. Much, much better. In pre-WWI days, how many men would have taken to destroy 100,000 people of Hiroshima. Now, it only requires a few handful of very smart ones? This is the reason why I think we should discount just death counts to track aggression in today's world.
Either way, increasing or decreasing aggression may be too complex a subject to generalize. But I kinda agree with Oni, when circumstances involve fear or survival, man will be moved to be more aggressive. If true, man hasn't changed much at all, has he?
This is one of my most favorites quotes. I wish all potential servicemen considering a military career would read it carefully:
Why of course the people don't want war. Why should some poor slob on a farm want to risk his life in a war when the best he can get out of it is to come back to his farm in one piece? Naturally the common people don't want war neither in Russia, nor in England, nor for that matter in Germany. That is understood. But, after all, it is the leaders of the country who determine the policy and it is always a simple matter to drag the people along, whether it is a democracy, or a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the peacemakers for lack of patriotism and exposing the country to danger. It works the same in any country.
Hermann Goering