Polygyny is a topic that existed in a great amoung of societies that are being investigated by anthropologist. In the Standard Cross-Cultural Sample (SCCS), 83.8% of societies are socially polygynous; 28% are coded as more than 40% of marriages being polygynous. However, the proportion of polygynous marriage could be small, especially in hunter-gatherer or foraging societies where people gather resources or wealth through collecting and accumulation. Under this condition, polygyny may thus be a facultative reproductive strategy that increased with defensible resources such as the human labor that could be used in food collection and tool making. Studies showed that this derives from animal behavior; for example, polygynous male birds compete for female birds by occupying a great piece of territory, which contains a large amount of vegetation to serve for breeding (Barber, 2008). When applied to human, the resource-defense theory indicates that polygyny achieve equivalent reproductive success or inclusive fitness, by sharing the resources of a wealthy man as they would through monogamous marriage to a poorer husband (Hames, 1996).
Even though the resource-defense explanation for polygyny is well supported by data on animal breeding system, some anthropologist, such as White (1998) questioned its relevance with to our species, even if some other anthropologists disagree. This research introduced several resource-defense hypothesis and those of key rival determinants of polygyny. More specifically, scarcity of males resulted from male-male competition and severe climate, using data from the SCCS of women in polygynous or monogynous unions in 186 societies with data broken down into over one thousand variables.
Assuming that the social and ecological responses react to the motivation of promoting human fitness, in other words, the ability of reproductive success of individuals, a large number of explanations of polygyny are possible. This resource-defense interpretation assumes that economic resources are defensible by individual men through several aspects, for instance, ownership of land, domestic animals, or money. Back to the bird case, land ownership in the human case perfectly analogous to the breeding territory, or the defense of harems, by dominant males of other vertebrate species (Brown, 1975). However, instead of competing directly over women, men compete for the resources that women require for reproductive success.
Women, in this case, select men based on their ability to gather and provide resources of reproductive success relevance. Other than that, women may also select their partner according to their great genes, or heritable fitness. Under most circumstances, males of upper-class in each society have better ability to gain and easier access to resources that promote reproductive success, while they are usually of great genes and fitness based on the class that they were born in. These upper class men can attract females in...