Final answer:
The major factors that influence common social structures shared by most primates include female mate choice, cooperation, and differences in male and female anatomy and behavior.
Step-by-step explanation:
The major factors that influence common social structures shared by most primates include the role of females in mate choice, cooperation among primates, and the differences in male and female anatomy and behavior.
Females of most primate species actively exercise their preference to mate with certain male 'friends' rather than aggressive or dominant males. This preference contributes to the social structure and has been observed in many primate species.
Cooperation is also a prominent feature of primate social life. While competition for resources exists, cooperation is often recognized as the central feature of primate social structures.
Additionally, differences in male and female anatomy and behavior, such as the ability of females to experience pregnancy and care for offspring, play a role in shaping the social structure of primates.