I think before that what happens when two opposing hunter-gatherers wind up competing for the same resources? They shook hands? I doubt it.Now if one guy has fish and you have venison you will trade if you both want venison someone is getting an atl atl arrow to the face.
The groups that took longer to become cultivators(or that never did) are the ones that lost out in the long run because the societies that could produce their on food rather than forage where able to have full time warriors and full time farmers the hunter-gatherers they lacked this luxury so the hunter-gatherers got dominated by the farmers.
Ever read "Guns,Germs and Steal"?It is a very interesting book I used to discus this book with others in the military that had read it the author goes into great detail about this topic.For the hunter-gatherers combat was to be avoided if at all possible for the cultivators they where able to develop more advanced societies faster and therefore armies.Cultivation of food means that you produce an abundance of it which means that you can feed an army but you keep wanting more and more dominate those that are inferior get more land to cultivate build a bigger army.Of course it is a theory but it makes a lot of sense if you think about it.
http://en.wikipedia.org/wiki/Guns,_Germs,_and_Steel