Sexual Division of Labor: To Cooperate or not to Cooperate?

Rebecca Bird’s “Cooperation and Conflict: The Behavioral Ecology of the Sexual Division of Labor” examines gendered differences in human subsistence behavior and attempts to provide ecological explanations for this division of labor that might be applied to human evolution and early hominid development. By exploring themes of cooperation and conflict in child-care provisioning, child-care constraints, reproductive goals, altruism and signaling, Bird concludes that cooperation alone does not maintain sexual division of labor but rather the conflict hypothesis is likely to maintain sex differences in subsistence.

The cooperation model suggests that by specializing in different resource acquisition, males and females are likely to maximize energy intake. David Lack suggested that a cooperative provisioning would ensure a higher reproductive success rate for both males and females. This is particularly true if resources are hard to locate. Lack’s hypothesis was based on the observation that nearly 90% of bird species participate in monogamous mating to insure stability in partnership (when insects were the primary diet base). In areas where resources are more easily located, an individual is likely to be self-sufficient and cooperation might collapse (67). It was eventually found that cooperation among the sexes for paternal care did not actually represent equal investment nor equal benefits. For example, male reproductive success is hindered by monogamy in that males have a higher variability than females. That is, males could acquire more fitness-related benefits by mating with more females. It is likely that a type of fathering that is less conflictual with reproductive fitness but less beneficial to offspring is engaged in. Bird argues that although female mate competition is rarely advantageous, if males control access to resources needed by females to reproduce (other than a new sexy pair of gametes), females might attempt to reproduce with many males in attempt to secure needed resources and might attempt to prevent their mates from mating with other females (67).

Bird argues that if sexual division of labor (SDL) results in specialization that would increase provisioning efficiency, three testable hypotheses emerge: 1) gender specialization would increase food going into the household in comparison to non-specialized cases, 2) male resource sharing should favor their own households, 3) men should have high payoffs for fathering in specialized cases.

Birds testable hypotheses are arguably geared towards the effects of specialization on males and male behavior rather than female behavior. What are some of the expected changes/differences in female behavior? Furthermore additional testable hypotheses include: higher success rates in subsistence acquisition (for example, in comparison to non-gendered specialized cases, or specialized males would have less success rates or greater energy cost-less efficient- in acquiring female-specialized resources and vice versa), greater variety in diet breadth and specialized tools.

Bird suggests that contrary to the notion that SDL would result in more reliable provision of food, Hiwi women have been found to contribute far greater than men. It has been shown that by participating in hunting, men loose out on the high returns that might be attained by aiding women in plant collection. Bird’s suggestion that Hiwi women contribute more than men goes against Gurven and Hill who claim that hunting is more productive than foraging where in the late wet season women who were pregnant and/or nursing collected 1,300cal/h, women not pregnant or nursing collected 1,600 cal/h and men collected 2,300 cal/h by hunting (although the reliability is not mentioned) (Gurven and Hill 53). Furthermore, Bird seems to equate caloric revenue as “contribution”. It should be noted however that women’s “caloric revenue” is mainly in the form of carbohydrates versus men’s “caloric revenue” include protein and lipids- both essential to human survival and functioning. Therefore, although women do not seem to gain calorie-wise in a specialized organization, they do in terms of the variety and essential nutrients provided by male contribution. Bird maintains however that even this need for a diversified diet does not explain why “sex differences exist… nor why it necessarily is men who obtain protein” (Bird 68).

Bird suggests that package size of acquired food plays a role in what and to whom food is shared with. She argued that “if big package hunting is primarily about fathering and provisioning, hunter-fathers must keep at least as much meat for their own households as they might if they had chosen small package hunting” (Bird 68). This does not seem to be the case with the Ache nor the Hazda. From this, Bird argues that costly hunting is engaged not because it provides for the family better but because it might “signal his quality as a mate or competitor” (71). The lack of evidence suggesting that providing meat gives male access to more sex leads Bird to suggest that the benefits of being a good under are indirect: the children of better hunters are less susceptible to mistreatment and infanticide and they are married to harder working women (71).

This however has been refuted by a recent study which suggests that hunters can and do influence or control distribution of meat. Kin, neighbors and cooperative partners are likely to receive a larger share of the kill as well as the nuclear family of the hunter. The hunter’s family has been shown to receive an average of 29.9kg/kill versus 13.5kg/kill which is distributed to other families (Gurven and Hill 54).

Furthermore, Bird states that “by hunting [males] can broadcast that skill to the large audience that is attracted to the kill. The fact that big game is shared is incidental” (72). This however brings into question the dynamics involved in large kills which are made successful by cooperation. To what extent do the men participate and how is individual skill recognized? How is more skill accorded to one hunter over the other and how does this get transferred from the kill site to the campsite? One would expect mechanisms that limit individual recognition or prestige to be in place when hunting is conducted in a group setting. How does this get altered when hierarchies (example chiefs participating in the hunt) are in place? It seems that signaling can only function if the group of males hunting allows for recognition of outstanding individuals, or if the group is composed of several hunting parties for attribution to a single individual is more likely in hunting of smaller game (which goes against the notion that hunting is costly behavior because of a lack of distribution control and physical danger).

Bird concludes that SDL will be stronger where males benefit more from investing in mating opportunities over provisioning ones.

Despite some data conflict with later published works, this paper is a good summary of the existing theories of SDL and gender specialization. It does however focus very heavily on an andocentric perspective of specialized subsistence costs and gains to the point where females are depicted as being acted upon, and simply having no choice in the matter. Females seem to have no choice but “cope” with the male’s preferred mating choices (to provide or not to provide?).

Also, it would have been insightful to provide additional ethnographic information that was not based solely on the Hazda or Hiwi.


Works Cited

Bird, Rebecca
1996 Cooperation and Conflict: The Behavioral Ecology of the Sexual Division of Labor. Evolutionary Anthropology: Issues, News and Reviews 8(2): 65-75.

Gurven, Michael and Kim Hill
2009 Why do Men Hunt? A Reevaluation of “Man The Hunter” and the Sexual Division of Labor. Current Anthropology 50(1): 51-74.