What Will We Do When We Have No War?
Perhaps the reason we continue killing each other is simply force of habit. The animal kingdom has never needed many males to keep their breeds going, so they fight each other over the most fit mothers. These fathers don't care whether the mothers will tend their young; they only care that they produce healthy offspring. What happens after that is not the concern of the father.
Human animals need many years of careful tending. This keeps the mothers vulnerable for, not only the gestation time, but for all the nurturing years. The brood must be protected for all these years. A mate who is not protective of the vulnerable in other areas of life is not likely to be a good human parent.
Competition must by tempered by compassion. Bonding becomes better than brutality in enforcing order. Self-discipline dictates the rules of the roost, understanding that animal children are imprinted with the actions of their same sex parents. By observing and imitating, they learn how to become their adult animal selves.
When we send our young men off to learn only how to compete and kill, how are they to learn human life lessons? When our women are made to cower at the command of an angry authority figure, how can they become competent caretakers?
Humans have the luxury of being able to bond with their young for a lifetime. Men must learn that this is a great blessing to all the earth. They must teach each other how to hold and be held by exhibiting this behavior with their sisters, mothers, mates, and children. The earth will do better when we admit we all need tender touch, not torture. Competition on the courses of sports arenas should be all the testosterone testing we need.