Behavioural measures of relationship quality.

*Based on a hypothetical dyad of individual A and B, the baseline asymmetry in the distribution of grooming was calculated using the following equation: (grooming received by individual A − grooming received by individual B)/(grooming received by individual A + grooming received by individual B).
†Based on a hypothetical dyad of individual A and B, the ‘opportunity to support’ was defined as the number of times individual A received aggression when individual B was in the group and potentially able to offer support to individual A.