The Shadow of the Future

The foundation of cooperation is not really trust, but the durability of the relationship. (p182)

Rapid turnover results in less cooperation within an organization – no reputation to uphold, no shadow of the future. (p183)

Promote cooperation by extending the shadow of the future
-increase frequency of interaction
-(by keeping others out of a neighborhood or territory, a small community can promote cooperation better than a larger community.)

The Evolution of Cooperation 
Robert Axelrod, 1984
revised edition w foreword by R. Dawkins, 2006

for further talk and controversial ideas against Axelrod's theory, see this Edge conversation:

ON "ITERATED PRISONER’S DILEMMA CONTAINS STRATEGIES THAT DOMINATE ANY EVOLUTIONARY OPPONENT" 
William H. Press,  Freeman Dyson [6.18.12]