The expendable male hypothesis

Abstract

Matriliny is a system of kinship in which descent and inheritance are conferred along the female line. The theoretically influential concept of the matrilineal puzzle posits that matriliny poses special problems for understanding men's roles in matrilineal societies. Ethnographic work describes the puzzle as the tension experienced by men between the desire to exert control over their natal kin (i.e. the lineage to which they belong) and over their affinal kin (i.e. their spouses and their biological children). Evolutionary work frames the paradox as one resulting from a man investing in his nieces and nephews at the expense of his own biological offspring. In both cases, the rationale for the puzzle rests on two fundamental assumptions: (i) that men are in positions of authority over women and over resources; and (ii) that men are interested in the outcomes of parenting. In this paper, we posit a novel hypothesis that suggests that certain ecological conditions render men expendable within local kinship configurations, nullifying the above assumptions. This arises when (i) women, without significant assistance from men, are capable of meeting the subsistence needs of their families; and (ii) men have little to gain from parental investment in children. We conclude that the expendable male hypothesis may explain the evolution of matriliny in numerous cases, and by noting that female-centred approaches that call into doubt assumptions inherent to male-centred models of kinship are justified in evolutionary perspective. This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals’.

Gender Differences in Social Networks Based on Prevailing Kinship Norms in the Mosuo of China

“…Other forms of subsistence, such as foraging or horticulture, are less likely to produce surpluses that support disproportionate reproduction among men, while others such as offshore fishing may remove men from their households for long periods of time. In these cases, women often contribute significantly to household production, or run their households with less consistent involvement from men (Mattison et al, 2019). A relatively high degree of women's autonomy amidst a limited ability among men to convert resources to reproductive success should be associated with less divergence in men's and women's relationship-building strategies.…”

The evolution of female-biased kinship in humans and other mammals

“…In their study of South Indian Tamils, Power & Ready [14] describe the importance of female kinship in a patrilineal, patrilocal context, where matrilateral kin often reside in close proximity to each other, provide important forms of support, and avoid the tensions among patrilineally related men competing for access to the same resources. At the same time, men are thought to play significant roles as maternal uncles in both male-biased and female-biased human kinship systems [38,39]; Starkweather & Keith [16] provide some of the first quantitative evidence of avuncular support by uncles of sisters' children in domains that plausibly enhance inclusive fitness without detracting from male investments in the uncle's own children. Matrifocal kinship (see glossary) also structures male social relationships: in Dominica-another nominally male-biased kinship system-matrifocality results in trade-offs between men's investments in conjugal relationships versus male-male support relationships [21].…”

One piece of the matrilineal puzzle: the socioecology of maternal uncle investment

“…R. Soc. B 374: 20180071 A maternal uncle should incur lower costs to investing in nieces and nephews when it does not negatively impact his ability to invest in his own children (see also [55]). For Shodagor uncles, this may be the case under multiple scenarios.…”