It's called learning agriculture.
Once we learned to grow food on farms etc, citystates were able to develop, and instead of spending all of our time trying to feed ourselves, we were able to put our time into creating civilizations, and making war.
War is the greatest reason for developmental leaps.
Trying to keep up with the jones's so the jones's don't kick your butt up around your ears is quite the motivation, or for that matter, wanting what the jones's have, and creating more and more sophisticated weapons to do it.
Farming, and then civilizations, and then war.
war has always been there, but on a very small scale, I am talking big wars, with thousands of soldiers, which was not viable when you are a hunting and gathering society.
Farming allowed civilization, and civilization created more sophisticated war making, and then war allowed leapfrog developements in technology.
Competition and free market economies will do that also.
Abel would disagree!