I believe this article is mostly right to the degree that in sparsely populated times, there probably wasn't much inter-tribal warfare until cultivation led to civilization and subsequent population growth. After that time the haves and have-nots had a problem.
War Before Civilization
by Lawrence H. Keeley
A single spearman isn't very useful. A mutually-supporting group of spear-carrying men is far more useful in defense or attack.
"Organized civilization is a rather late (10,000 years ago), development that was related to cultivation and domestication." -- shuckmaster
The 14,000 year figure probably (wild guess) came from the multirow barley sample of that RC date, which was dug up in the Middle East somewhere. Multirow barley means irrigation and domestication.
My view is, cultural development isn't either linear or uniform. Some develop stuff in nice, logical, Victorian-model stages, others don't, and still others find "illogical" leaps to be better.