Evolution vs. Revolution

As my 21 year old son cries revolution, I am prone to cry evolution. I believe the ability of the human species to reason has already evolved, it just hasn't caught on yet. The leap from cannabalism to capitalism took a long time and they are basically the same. How long does that mean it will take for people to realize that peace and justice are better than pride and greed. If we do not exstinct ourselves in the process I believe someday reason will catch on.