Here are my comments on letters from two correspondents of different age, culture and geographical latitude but with similar preoccupations. After addressing the generalities I will try to address the particular topic of each contributor. Territoriality is proper to practically all life forms. Competition - cooperation, like two scales, constantly change positions, first one prevailing then the other. The one favouring cooperation culminated in Communism and the other, in Fascism.
Human culture seems to evolve rather toward cooperation than competition.
We see from history that cooperation is the main factor in human evolution. It's enough to compare Athens to Sparta. The tribe, the clan, are expressions of cooperation at the local level and competition on a more global level. This saying expresses the belief that the local solidarity will always prevail over the global one. One beautiful outcome of local pride is the rich folklore we can enjoy.