The relative prevalence of direct, indirect and generalized reciprocity in macaque grooming exchanges

► We examine direct, indirect and generalised reciprocity of grooming in macaques. ► Grooming was exchanged according to direct reciprocity. ► We found limited or no support for indirect or generalised reciprocity. ► We argue that direct reciprocity may be driven by a system of emotional bookkeeping. ► Such system does not require complex cognitive capacities.