Final answer:
Grooming between two un-related females of similar rank in primate societies is a complex behavior that plays a role in social bonding, alliance forming, and hierarchical structuring, reflecting both competitive and cooperative aspects of primate social life.
Step-by-step explanation:
The grooming between two un-related females of similar rank is a behavior that can be explained by the dynamics of primate social life, including aspects of competition and cooperation. This behavior does not neatly fall into patriarchal power dynamics or strictly polyandrous or polygynous mating systems, but rather showcases a complex interplay of social strategies where both males and females are central actors.
Female primates may groom each other to establish alliances, reinforce social bonds, or establish a hierarchical relationship, which can be important for survival and reproductive success within their social groups.
These interactions do not necessarily imply a mating system but could be part of broader social strategies that include the sharing of resources and the formation of coalitions among females, which in turn may influence mating dynamics indirectly. This understanding aligns with broader research showing that female primates exhibit behaviors that reflect both competitive and cooperative elements, underscoring their importance in the social structure of primate societies.