Table 3 Results of CUG tests.

Results of our CUG tests, with empirical values of network statistics and the probability of observing a greater value in a random network of the same size and density.

 Empiricalvalue Probability versussimulations Direct reciprocity 0.23 <0.001 Hierarchical reciprocity(transitivity) 0.38 <0.001 Modularity 0.38 0.014 Clustering 0.40 0.019 Exhibiting tolerancecentralization 0.26 0.060 Receiving tolerancecentralization 0.18 0.299