Is war just a part of Natural selection?

War is obviously a natural part of human behavior, but that doesn't mean that we can't learn to control it. Unlike many organisms which are driven by instincts they can not control, we have the ability to choose, although it's very difficult for people (as opposed to a single person to adhere to a choice).

In a general sense, any event (from War to Natural Disaster) which affects the reproductive flow of a population becomes a force of natural selection. Although in recent years, human activities like wars are seldom consistent over a long enough timeframe to have any real effect on biological selection.

On the other hand, wars have a much more direct effect on cultural (as opposed to biological) evolution. The speed of cultural selection is many orders of magnitude higher than biological selection.

A few pockets of ethnically unique people still exist on the planet and they are at risk of vanishing, but more often than not, they vanish by being absorbed into the larger population. Their cultures vanish and any uniqueness in ethnicity is blended into the larger populations. The American Indians are a good example. Even though their culture is gone (or greatly reduced), their biology is still with us, and is now a part of many of us.

Ultimately as modern travel erodes the isolation of populations, all of humanity will be absorbed into a more homogenous single ethnic race. Our differences will diminish. The same thing will happen to cultures. It's already happening.

You have a very optimistic way of looking at mankind. Sure given enough time and travelling humanity would become more homogenous but just looking at last century we allmost destroyed the whole world with atomic bombs. Thinking more realistic we need a big change and fast to control that it will not happend. The only way to change the future is to educate our children now so that they will not make the same mistakes. World culture and unity is now utopia but so was travelling to moon 100 years ago. We need to make the change now. Talking about it dosen´t change anything so I planned to go work for Uniceff or other organization like that. I have the knowledge about the world and the situation like many people from the Western world it just one step more to actually do something about it and use your knowledge for better tomorrow.