Finally, a promising theory that may explain why too much peace or too much war
is bad. For cognition-challenged, replace 'biofilm' with your favourite
organisational form, nettime included, and pick your own 'evolved cheats' ;-)

Explaining cooperation is a challenge for evolutionary biology. Surprisingly,
the role of extrinsic ecological parameters remains largely unconsidered.
Disturbances are widespread in nature and have evolutionary consequences. We
develop a mathematical model predicting that cooperative traits most readily
evolve at intermediate disturbance. Under infrequent disturbance, cooperation
breaks down through the accumulation of evolved cheats. Higher rates of
disturbance prevent this because the resulting bottlenecks increase genetic
structuring (relatedness) promoting kin selection for cooperation. However,
cooperation cannot be sustained under very frequent disturbance if population
density remains below the level required for successful cooperation. We tested
these predictions by using cooperative biofilm formation by the bacterium
Pseudomonas fluorescens. The proportion of biofilm-forming bacteria peaked at
intermediate disturbance, in a manner consistent with model predictions. Under
infrequent and intermediate disturbance, most bacteria occupied the biofilm,
but the proportion of cheats was higher under less frequent disturbance. Under
frequent disturbance, many bacteria did not occupy the biofilm, suggesting that
biofilm dwelling was not as beneficial under frequent versus intermediate
disturbance. Given the ubiquity of disturbances in nature, these results
suggest that they may play a major role in the evolution of social traits in

(of original message)

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