Cooperative Breeding Hypothesis

Discussion

Cathryn Townsend :

"Turning to the question of how gender egalitarianism may have evolved, evolutionary anthropologist Kristen Hawkes and colleagues have suggested that the reason postmenopausal women survive long past their reproductive years is that their role in helping to care and provide for the offspring of closely related kin was adaptive.

This is known as “the grandmother hypothesis.” Anthropologist and primatologist Sarah Blafer Hrdy (2009) has extended the grandmother hypothesis to form a broader “cooperative breeding hypothesis.” She argues that the human cognitive capacity for intersubjectivity is the evolutionary legacy of caregiving interactions between infants, mothers, and other kin. Cooperative caregiving was required to support the heavy energetic demands of evolving human offspring. Emerging in Homo erectus as brain sizes increased, this is initially likely to have been provided mostly by female kin due to variable male commitment to child rearing. This theory is supported by studies which show a high level of alloparenting in contemporary hunter-gatherer societies. Evolutionary anthropologist Camilla Power links the cooperative breeding hypothesis with the emergence of egalitarianism and symbolic culture in her “female cosmetic coalition” (FCC) model (2009). She suggests that egalitarianism, ritual, and symbolic culture came about as the result of the new female reproductive strategies that began with cooperative breeding. If Power’s model is correct, female kin coalitions would have used deceptive or cosmetic sexual signals to secure the increased male investment necessary to bear the escalating costs of producing large-brained infants. Reduced reproductive competition between males was a precondition required to afford the levels of pro-sociality, intersubjectivity, and male investment in childcare required for the final phase of rapid brain expansion and the emergence of language 300,000 to 200,000 years ago. Thus, by the logic of Power’s theory, dominance leveling between males was driven initially by female collective ritual strategies aiming to minimize female reproductive stress. These conditions would have facilitated also the creation of those aspects of gen- der equality observed among extant immediate-return hunter-gatherers—for example, female alliances, lack of reproductive coercion, and relatively high male investment in child provisioning and childcare. Male reproductive strategies would have also changed in response to the new female strategies, with investing males becoming choosier about their mates as their reproductive efforts became more costly.

Cooperative breeding theories and Power’s FCC model suggest a mechanism whereby the dominance of alpha males could have been neutralized. They are consistent with Boehm’s reverse dominance hypothesis. Rituals which propagate egalitarian gender relations play an important role in maintaining the political equilibrium of extant noncompetitive egalitarian hunter-gatherer societies. For example, Lewis (2014) describes how Congo Basin hunter-gatherers employ extensive ritual practices based on gendered coalitions to support gender-egalitarian relations in everyday life. Te fact that humans do not follow the usual male competition/female choice (MCFC) model of sexual selection has been argued for by evolutionary psychologists Steve Stewart-Williams and Andrew Tomas (2013), who propose instead an MMC (mutual mate choice) model. There is strong justification for such a shift in terms of the sexual selection pressures that would have come about with increased encephalization, including heightened female reproductive costs and a concomitant increase in male provisioning. Furthermore, the increased effort to males in obtaining sexual access, in terms of the theory of parental investment and sexual selection, means that males should have become choosier and females more competitive.

Te reemergence of gender inequality can form the basis by which other types of social inequalities are established—for example, due to an increase in male reproductive competition that comes about with differential property ownership and polygyny. This includes two domains of potentially important insights into human political behavior, namely (1) the mechanisms whereby noncompetitive egalitarianism first arose and then became firmly established among early Homo sapiens in the African Middle Stone Age and (2) the mechanisms whereby inequalities may have reemerged with the cultural evolution of politically complex societies from approximately 40,000 years ago onward.

David Wengrow and David Graeber (2015) suggest that alternation between egalitarian and hierarchical political organization was an emergent property of hunter-gatherer societies in the highly seasonal environments of the Upper Paleolithic in Europe."

(https://www.academia.edu/29417676/Egalitarianism_the_evolution_of)