Final answer:
The two primary factors influencing primate social groups are reproductive roles, where females often center around offspring care, and social strategies, where both sexes compete and cooperate for resources and relationships. Sexual dimorphism also plays a role in the social structure of primates.
Step-by-step explanation:
The two factors that play a major role in the type of social group a primate species forms are related to reproductive roles and social strategies for accessing resources. The first factor is that adult female primates spend much of their adult lives pregnant or nursing, focusing more on offspring care than adult males, who may engage in different social strategies. This directly impacts the social group dynamics, with females often forming the core of primate societies.
The second factor is related to social organization and the roles primates play in their strategic pursuit of resources, relationships, and reproductive success. Females may be sexually assertive and choose mating partners based on friendliness rather than dominance, while males may opt for friendliness over aggression as a reproductive strategy. Both sexes participate in both competitive and cooperative behaviors, which shape the complexity of primate social groups.
Furthermore, evidence of sexual dimorphism, such as size differences between males and females, can influence the social structure within primate groups. High levels of sexual dimorphism might correlate with male dominance and competition, as seen in gorilla societies, while a lower level may be indicative of more monogamous relationships, as observed in gibbons.