The Relative Status View of History
Evolutionary Psychology implies that conflict occurs when there is no clear status hierarchy or when one group decides to challenge the existing hierarchy. The conflict continues until a new equilibrium hierarchy is established. For example, World War I occurred because Germany (after centuries of internal division and disorganization) had finally caught up with and exceeded Great Britain and France in power. Yet the world was still dominated by the British and French empires, which together dominated almost half the globe. In other words, the German Empire was a first rate power, the most powerful single nation in Europe, yet they were treated as second rate as compared to the global empires of France and Great Britain.
After the western powers and Russia teamed up, and (barely) managed to defeat the German Empire, Germany was forced to accept humiliating terms that forced Germany to accept an unnaturally subordinate status in Europe. From an Evolutionary Psychology perspective, this made another war inevitable.