LImit a resource and lets see how cutthroat all our countries get... and I am not talking about a resource necessary for the economic growth, but a resource necessary for a population's survival. All of a sudden killing the other guys becomes a survival necessity. I think the logic chain would be that some would venture out into space due to lack of resources. They will arm themselves with the same technology they needed to win the last great war on their home world. They will venture forth and take the resources they need to survive. This seems reasonable to me given scarce resources. The question is whether "technology" and population controls can buy a society out of the scarce resource problem.