Marriage patterns in a Mesoamerican peasant community are biologically adaptive

Abstract

Differential investment in offspring by parental and progeny gender has been discussed and periodically analyzed for the past 80 years as an evolutionary adaptive strategy. Parental investment theory suggests that parents in poor condition have offspring in poor condition. Conversely, parents in good condition give rise to offspring in good condition. As formalized in the Trivers-Willard hypothesis (TWH), investment in daughters will be greater under poor conditions while sons receive greater parental investment under good conditions. Condition is ultimately equated to offspring reproductive fitness, with parents apparently using a strategy to maximize their genetic contribution to future generations. Analyses of sex ratio have been used to support parental investment theory and in many instances, though not all, results provide support for TWH. In the present investigation, economic strategies were analyzed in the context of offspring sex ratio and survival to reproductive age in a Zapotec-speaking community in the Valley of Oaxaca, southern Mexico. Growth status of children, adult stature, and agricultural resources were analyzed as proxies for parental and progeny condition in present and prior generations. Traditional marriage practice in Mesoamerican peasant communities is patrilocal postnuptial residence with investments largely favoring sons. The alternative, practiced by ∼25% of parents, is matrilocal postnuptial residence which is an investment favoring daughters. Results indicated that sex ratio of offspring survival to reproductive age was related to economic strategy and differed significantly between the patrilocal and matrilocal strategies. Variance in sex ratio was affected by condition of parents and significant differences in survival to reproductive age were strongly associated with economic strategy. While the results strongly support TWH, further studies in traditional anthropological populations are needed.

The magnitude of changes in linear growth within Taiwanese families: intrinsic sex‐associated biology, socially mediated behaviors, or both?

“…One is the potential for cultural beliefs and actions to bias parental care in favor of one sex, usually males. Despite wide recognition, impacts of sex‐biased preferential care remain infrequently considered (Crooks, ; Little & Malina, ; May, Goodman, & Meindl, ; Stinson, ). The second is that there is an alternative, and contradictory, set of expectations if female growth is more canalized.…”

The Intersection of Tradition and Choice: A Study of Spouse Selection in Pakistan’s Nomadic Tribe

“…While making a comparative analysis of the existing literature and the empirical evidence derived from the in-depth interviews, a number of commonalities and differences were found in the marriage patterns of the Bagri Tribe and the patterns in other communities of the world cited in the literature. Endogamy is a common factor in the marriage rituals of the Zeopotec-speaking community of the Oaxaca Valley, South Mexico, as investigated by (Little and Malina 2010) and the Bagri tribe. On the other hand, both Bagri Tribe and Zeopotec-speaking community deem marriage with a first cousin incest.…”

Natural selection and type 2 diabetes‐associated mortality in an isolated indigenous community in the valley of Oaxaca, southern Mexico

“…Records for each individual included: date of birth, date of death, age, sex, cause(s) of death, parents’ names, birth place, and whether or not cause of death was verified by a healthcare professional (nurse, physician). Mortality data were linked with genealogies for households in the community used in prior studies (Little & Malina, ), and were used to determine whether or not there was a family history of T2D in a descendant's first‐degree relatives.…”