Preference for sons and sex ratio in two non-Western societies.

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.

Do "helpers at the nest" increase their parents' reproductive success?

"Helpers at the nest," usually offspring of a preceding litter who contribute by feeding the young to increase the reproductive success of a breeding pair, are known in many species of birds and mammals. Although similar behaviors were described by ethnological observations in several human societies, there is a lack of data on their existence and role. This study of 794 reproductive life histories of post-menopausal Berber women of Southern Morocco aims to provide such information. Results show that the presence of "probable helpers" in the household is related to higher fertility scores and is associated with improved survival of offspring to sexual maturity. In contrast to sparse observations from other human societies, there is no indication that child caretaking would be specific to eldest daughters. Although the association between offspring survival and helping patterns seems highly probable, there is no confirmation that child caretaking per se is the relevant variable. Contrary to nonhuman helpers at the nest, workloads of children range from housekeeping to light agricultural tasks, and are not focused on assisting younger siblings. The improvement of reproductive success is probably the result of multiple interactions, among which the network of kinship would play a role at both the levels of economy and reciprocal assistance.

Secular trend in age at menarche in Marrakesh (Morocco).

The median age at menarche observed by status-quo methods in 1991, and calculated by mean of probit analysis in a sample of 239 school girls from Marrakesh aged 11-17 years, was 13.75 +/- 0.17 years. Compared with earlier observations obtained for Moroccan girls in 1982 and 1987 the results show a decline of age at menarche of 0.55 year in the period 1982-91 and 0.25 year in the period 1987-91.

Determinants of contraceptive use in Morocco: stopping behaviour in traditional populations.

The determinants of modern contraceptive use in traditional populations are analysed in married women aged 30-44 living in the province of Marrakech (Morocco). Women who have never used contraception have smaller family sizes than those who do: the number of live children (or live births) is the variable with maximum predictive power on contraceptive use, while child mortality is the main inhibiting factor. The probability of contraceptive use increases with female age at marriage and decreases with the woman's age, indicating a generational change in reproductive behaviour. The socioeconomic variables education, employment and residence, have no significant independent predictive character on contraceptive use, although the interaction between education and residence does. The paper evaluates the hypothesis that traditional populations in the initial phase of their demographic transition resort to modern contraception in order to stop childbearing, when they have reached a desired number of children, rather than to space births or reduce their fertility.

PIP: The authors conclude that the determinants of contraceptive use among the rural population in Marrakech province, Morocco, were multiple and interrelated in complex ways. Birth control was a consequence of changes at both the individual and social levels. Findings indicate that women who had never used contraception had smaller family sizes than those women who used contraception. Contraceptive users had a significantly higher number of live births and living children. Child mortality was significantly greater among noncontracepting women. Contraceptive users had a significantly longer reproductive period than nonusers, which was attributed to a longer delay in the last live birth. Logistic models show that significant independent predictors of contraceptive use were the number of live births, the number of children who died before the age of 5, the age of the mother, the type of marriage, and the age at first marriage. The probability of access to contraceptives decreased with under-5 mortality, female age, marriage age, and increases in polygynous unions. This model explained 63.9% of the variance. Although residence and educational level did not significantly increase the fit of the model, the probability of contraceptive use did increase in relation to urban residence and a basic educational level. The number of live children was a predictor of contraceptive use but the best predictor of contraceptive use was family size (65.8%). The probability of contraceptive use increased among women with three or more children. Female education had no independent predictive impact on contraceptive use. Contraceptive use increased among women in polygynous unions, regardless of residence or schooling.