Men doesn't improve, only science&technology does :P All cultural ideas have been around now since the times of ancient greece, the only thing that changed are our tools.

I disagree with your idea because the biggest improvements we're made in times of peace, but some technologies (mainly weapons tough) seem to evolve way faster in times of war (for obvious reasons). That being said, in the first instance EVERY war means a great loss of ressources - the only reason people do it because they have certain expectations of how the future might be like, and that their influence created during conflicts is worth the money in the end. That might be true for most wars that occured in history, but since WWII every war was a waste of ressources, or just lead to stop further vanishing of those. Also - the technology we got now is enough for dozens of overkills, there is fewer need to create bigger weapons than before, now it's interesting to find ways to use them even faster/find a way to move an object from one part of the world to the other in under 10 minutes.

And to end it all with my personal guess on your question: Pussy, Food & a place to shit&sleep :D Science evolved because people wanted to chill&fuck as much as possible without being disturbed by the limitations of the physical world.