Saturday, February 04, 2006

Male Provisioning, Polygyny Constraints, and Sexual Selection


Male Provisioning, Polygyny Constraints, and Sexual Selection

To overcome the challenges of the harsh Arctic climate, they created new forms of fuel, clothing, and shelter. To overcome the challenges of a different food supply, they reallocated the tasks of food procurement between men and women. This shift in food procurement is evident if we compare present-day hunter-gatherers from the Tropics and the Arctic.

In the tropical zone, men hunt while women gather berries, fruits, roots, grubs, eggs, and other sessile food items, these tasks being more compatible with the demands of pregnancy, breast-feeding, and infant transport (Kelly 1995:268-269).

Further north, food gathering is limited by the long winter, providing less than 10% of all food among hunter-gatherers above 60° N, as compared to 40-55% below 40° N (Martin 1974:16-18). The end point of this trend is Arctic tundra, where almost all of the available biomass is in the form of game animals. Such environments compel women to process food obtained through hunting instead of gathering food on their own.
Hoffecker discusses the implications (p. 8). First, “hunter-gatherers in northern continental environments who subsist on terrestrial mammals must forage across large areas in order to secure highly dispersed and mobile prey.” Second, “[a]nother consequence of low temperatures and a high meat diet is that males procure most or all food resources.”

This change in the sexual division of labour would have had demographic and, ultimately, evolutionary consequences. As hunters cover longer distances, they increase their risk of death from starvation, accidents, or inclement weather, a risk that is already high because they carry a minimum of supplies for sustenance and shelter. If we look at present-day Arctic groups with no herd dogs or domesticated reindeer (e.g., the Chukchi), male mortality rises sharply with hunting distance (Krupnik 1985).

In addition, hunting is more hazardous in the Arctic because of the extreme weather and the relative absence of alternate food sources for hunting parties. There thus develops a male deficit in the sex ratio. Among 19th century Labrador Inuit, the 15+ age bracket had only 57 males for every 100 females (Scheffel 1984).
Few of the excess women, however, can become second wives. This is because of the high demands on male provisioning. In his review of Inuit mating systems, Kjellström (1973:118) concludes, "Since the duty of being a provider was more onerous for the man who had two or more wives, this meant that as a rule it was only the really able and skilful hunters and fishers who could manage this double duty." Together, these two factors-high male mortality and limited polygyny-skew the operational sex ratio towards a female surplus, thereby causing women to compete more intensely for mates. One result is an intensification of sexual selection.


Ann Þ

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