Preference for sons and sex ratio in two non‐western societies

Abstract

Moroccan Berbers and the Bolivian Aymara are two unrelated peasant groups living in adverse environments with a still rather traditional agriculture. Precarious life conditions may be responsible for the importance given to male labor and hence for the cultural preference conferred on male descent. This preference, expressed in the social valorization of sons to the detriment of daughters, is more emphasized if the socioeconomic status of the family is lower. Interpreted according to the cost/benefit approach of Fisher (1958 Genetical Theory of Natural Selection, New York: Dover) of variations in the sex ratio and to its later developments (Trivers and Willard 1973 Science 179:90-91; Trivers 1985 Social Evolution, Menlo Park: Benjamin/Cummings; Hewlett 1991 J. Anthropol. Res. 47:1-37; Smith 1993 Ethol. Sociobiol. 14:39-44), these cultural characteristics could determine that parents bias the care allocated to their progeny in favor of sons, to the detriment of daughters. This could eventually affect their respective survival and finally modify the offspring tertiary sex ratio. This study compares differences in survival as indicators of parental care according to a child's sex and across three economic strata: poor, medium, and high. The Moroccan data express no other sex differences in survival than an advantage for daughters during the preweaning period in the medium and high strata. Within the same sex and across economic strata, a greater mortality between age 10-20 years is observed for boys of the poorest stratum. The Aymara data do not show sex differences by economic stratum, except for an advantage to daughters between birth and 5 years in the medium group, and no survival differences within the same sex across economic strata. These results suggest either that despite the social valorization of male progeny no differences in parental care according to sex occur, or that their magnitude is not great enough to contrast the survival of sons and daughters.

Boys are more stunted than girls in Sub-Saharan Africa: a meta-analysis of 16 demographic and health surveys

“…On the basis of a study of gender biases among the Mukogodo of Kenya, Cronk [20] suggested that favouritism towards daughters occurred as a result of lowered socio-economic status. However, there are also studies that report greater social valorisation of sons at the detriment of daughters [21], including dietary discrimination [22], thereby dispelling conclusions of a nutritionally advantaged position of female over male children.…”

Child undernutrition in Kenya: trend analyses from 1993 to 2008–09

“…The high prevalence in stunting among boys as compared to girls is in agreement with the literature on stunting in sub-Saharan Africa [11], but the improvement over time in boys, more so than in girls, is difficult to explain. Looking to family dynamics, the literature on parental sex bias in relation to child care and feeding practices is contradictory and the evidence for bias is scarce [12,13,35]. DHS data have been brought to bear on this subject, but only via indirect inferences based on parental education differences [35].…”

“…In sub-Saharan Africa, boys have consistently posted higher rates of stunting compared to girls [11]. Many (sometimes contradicting) reasons have been hypothesized to explain the sex difference, such as gender-differentiated feeding practices [12,13]. It is also postulated that girls are physically less active and therefore spend less energy compared to boys, and that boys are more vulnerable to acute respiratory infection and diarrhoea [14].…”

No evidence for sex biases in milk macronutrients, energy, or breastfeeding frequency in a sample of filipino mothers

“…For humans, differences in reproductive investment may take the form of neglect of offspring of one sex (usually females), including infanticide and sex-specific abortions (Wilcox and Baird, 2011), differential nursing frequency by offspring sex, or longer overall breastfeeding durations prior to weaning, as well as increased volume transfer of milk, all largely behavioral differences in offspring rearing. While these behavioral differences vary within and between populations, the overall impact in some populations (excluding outright neglect) may be marginal (Crognier, 2006). Humans do, however, reflect an unusual application of sex-based differences in offspring investment, as reproductive investment by offspring sex may be highly variable independent of maternal condition or resources and likely reflect variable social beliefs and practices rather than biological differences.…”