  We show that fluid organizations display higher levels of cooperation than
attainable by groups with either a fixed social structure or lacking one
altogether. By moving within the organization, individuals cause restructurings
that facilitate cooperation. Computer experiments simulating fluid
organizations faced with a social dilemma reveal a myriad of complex
cooperative behaviors that result from the interplay between individual
strategies and structural changes. Significantly, fluid organizations can
display long cycles of sustained cooperation interrupted by short bursts of
defection.
