Thought Provoking Fun

Imagine two cavemen with their families.  Suppose they roam the earth without running into any other members of their kind until one day they happen across one another.  Do the two cavemen decide to live with one another?  If they do, why?  In my experience, libertarians and communitarians answer this question differently.  If you are unfamiliar with typical libertarian and communitarian answers, then you may end up giving an answer that belongs to the opposite end of the political spectrum.  That is, you may consider yourself libertarian or communitarian but support the opposite side with your fundamental beliefs regarding human nature.