Relationships between two or more females that are based on mutual benefit
When females have abundant resources, they birth more offspring and have more offspring survival than females who have limited resources (Mulder 1987). Allies who share a common goal are likely to share resources, so individuals who form alliances have a greater likelihood of survival and reproduction than individuals who do not form alliances (Chapais 1995). Female-female alliances are often formed for food competition, particularly among nonhuman primates, but alliances afford females a variety of advantages including physical protection, emotional support, and child care.
Benefits of Female-Female Alliances
Alliances increase reproductive fitness, or one’s ability to pass genes to subsequent generations, by enhancing one’s ability to secure and maintain resources. Food and status are common resources obtained through alliances (Chapais 1995). Another valuable resource, particularly among human mothers, is child care (Hrdy 2009). Human infants are born altricial – they require extensive care for survival. Allomothers, or caregivers other than the mother or genetic father, are highly valuable to a mother. If a mother does not have kin nearby, a female-female alliance that results in child care increases her children’s likelihood of survival.
Female-female alliances are also associated with mental health advantages. Women’s friendships are characterized by high levels of social support and self-disclosure, which are thought to positively impact mental health (Uchino et al. 1999). The more female friends co-ruminate, or discuss negative feeling and experiences, the closer they feel to their friend (Rose 2002). Another benefit of female-female alliances is support during competition with rivals. Women’s intrasexual competition typically occurs by indirect actions such as gossip and rumor spreading aimed to promote equality (Campbell 1992).
Costs of Female-Female Alliances
Although some aspects of women’s same-sex friendships promote mental health, other aspects may negatively impact health. Co-rumination among girls and adolescents predicts increased anxiety and depression over time (Rose 2002), and co-rumination among women is associated with increased levels of physiological stress (Byrd-Craven et al. 2011).
Women’s same-sex friendships are also fragile relative to men’s same-sex friendships (Benenson and Christakos 2003). Competition for resources, such as attention from a mate or status, can dissolve an alliance. If women portray themselves as superior to their allies, exclusion from the group is a likely consequence (Campbell 1992).
With Whom Do Females Form Alliances
Genetic relatedness, similar social status, and similar age are variables that increase the likelihood that females will form an alliance (Chapais 1995). Indeed, maternal kinship bonds are one of the primary sources of social status and alliance formation among many nonhuman primates. Alliances form among females who share similar goals such as guarding food and mates (Rucas, Gurven, Winking, and Kaplan, 2012). Familiarity is also a factor in alliance formations. Females are more likely to be allies the more often they interact socially (Dunbar 1980).
High-status females tend to form alliances with other high-status females, and befriending a high-status female can increase one’s own social status (Chapais 1995). Females sometimes betray kin and close friends if a prospective ally can help them improve or maintain their own rank (Benenson 2013). Moving up the social rank by forming an alliance with a high-status female is rare because there is little advantage to a high-status female to forming an alliance with a low-status female. Although alliances typically form between individuals of similar social status, there are exceptions. In bridging alliances, one ally is ranked below a target, and the other ally is ranked above the target (Chapais 1995). The alliance results in the lower ranked ally moving up in rank above the target. In a revolutionary alliance, both allies initially rank below the target but both move up in rank above the target after the alliance.
Female-female alliances are relationships between two or more females that are based on mutual benefit. Alliances enhance an individual’s ability to secure and maintain resources, which ultimately increase one’s reproductive fitness. Some of the resources that females secure through alliances are food, territory, status, mates, and child care. Female same-sex friendships can provide social support, but they can also increase physiological stress. Alliances between women are based on equality, and they are quick to dissolve if an individual is perceived as acting superior to the group.