The risk of inspecting predators.

ls T > R?

Groups of guppies with low inspectors, medium inspectors, and high inspectors were placed with a predator.

The probability of surviving 36 hours was a function of inspection frequency, with those inspecting most often suffering the highest mortality.

This cost implies that each fish is tempted to defect (stop inspecting) when its partner cooperates (inspects) - assuming the former can get some information from the latter.