There are very few people at any given moment in history that can actually start a war. These people usually work very hard to get into such a position, to acquire the power necessary. They say that power corrupts, but I tend to believe the opposite. That power attracts the corruptible. And the corrupt at heart have no problem sending people to die to fulfill their agendas.
Don't blame humanity as a whole, or if you must, don't blame them for being warlike, blame them for being too gullible not to be able to see through the bullshit after all these centuries.
The Rev