It's believed that these instincts are either biological or culturally influenced. However, one fact remains clear, by the end of the prehistoric times man was a fighter, capable of waging organized warfare on his other human ancestors. By the time man had first learned how to write, he already had wars to write about. War, is a universal social activity which patterns military organization within prehistoric primitive societies, which are as important as the political, economic and religious systems that were developed during early man. War began only after the early man had acquired the intelligence to perform it.
War takes teamwork and cooperation between individuals.
It requires learning and can be practiced efficiently only after intensive training, usually accompanied by firm, sometimes savage, discipline. It is potentially dangerous, more so than hunting and much more so than political, religious, and economic activities. However, out of this some what order, some problems such as civil war and even rebellion can emerge from this organized structure. War has some differences, such as in prehistoric war, populations did not share a common frontier. There was a no man's land between settlements, and most military confrontations began there.