Bonnet females form strong bonds with their maternal kin, intervene on behalf of kin in agonistic disputes, and establish stable matrilineal dominance hierarchies. In this group, high rank conferred both social and reproductive advantages upon females. Daughters of low ranking females were persistently harassed and had high mortality. Male bonnets are unusual because they form close bonds with one another, groom often and sit together. Males also compete intensely over dominance status.
Males intervene often in disputes among males.
Both kinship and reciprocity influence alliances. Males actively recruited support, particularly from males who outranked themselves and their opponents, suggesting that males understand third party rank relationships. I analyzed food sharing patterns at Gombe and in a captive chimpanzee group.