That gene pool statement was great, come up with that yourself? Let's use your idea and see what happens. We'll have 100 people, half which want to fight, and half who don't. There will be a war every few years. The 50 warheads each take a side of the war and fight. Lets say 3/5 of them die. 20 of them left. The 50 "wussies" survive and procreate doubleing their numbers, now 100 "wussies" on earth. The 20 veterans procreate. Now 40 warheads. Here comes another war, a few years later, all the war heads sign up and go to the war. Let's say 3/5 die (again) 16 warheads left. The wussies survive and procreate doubleing their number. 200 wussies. The warheads do too. 32 warheads. I think you're starting to get the hang of it. This is just a basic illustration. Using only basic thoughts. Not including that probably more warheads will die than that and that the number isn't constant, and also the biological, chemical, and nuclear factors the warheads face.
I don't think the purpose of us being here on earth is to fight, it's just a major side effect of us not being able to govern ourselves.