Browsing by Autor "Crognier, E"

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Helping patterns and reproductive success in Aymara communities
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 2002) Crognier, E
Abstract. “Helpers at the nest,” young adults remaining in their parents home to take care of younger siblings, are known in many species of birds and mammals. Similar behaviors are occasionally observed in human societies but their frequency and significance for parental reproductive success are still not fully appraised. This study was designed to document this issue in a traditional Aymara peasant society of the Bolivian Altiplano. It is based on 359 reproductive life histories of women 45 years of age or older on a survey of children’s workload in 1998 and 1999. The presence of “potential helpers” in the household is significantly associated with higher fertility and with higher fertility and with improved survival of siblings to sexual maturity. Caretaking is not particularly assigned to older daughters. The positive relationship between the availability of offspring help and reproductive success does not demonstrate a causal role for child caretaking because, in contrast with nonhuman helpers, workloads of children range from housekeeping to agricultural tasks, instead of being focused on feeding or protecting younger siblings. Correlation and multiple regression analyses, however, suggest that the total amount of care given by the older offspring and the amount of care received by each recipient are, along with offspring contribution to household economy, among the determinants, of parental reproductive success.
Preference for sons and sex ratio in two non-western societies
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 2006) Crognier, E
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 Thoery 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.
Reproduction in high altitude aymara : physiological stress and fertility planning?
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 2002) Crognier, E
Summary. Reproductive characteristics at high altitude are described based on the reproductive histories of 720 Aymara women, collected in 1998 and 1999 in a group of twelve peasant communities at a mean altitude of 4000 m in the Bolivian Altiplano. The reproductive pattern is shaped by a late onset of childbearing, associated with a rather short reproductive span and large birth intervals. Environmental conditions could explain the particularly late age at menarche of rural girls compared with their urban counterparts, whereas the age at first birth is likely to be under cultural control. The short reproductive span appears to result from a large mean interval between last birth and menopause, which is essentially determined by cultural decisions. The birth intervals, which are longer than in many traditional societies, could be the result of a slower restoration of postpartum fecund ability induced by the hard way of life inherent in the Altiplano (including poor sanitary and nutritional conditions and high workload), perhaps aggravated by hypoxia. However, a secular trend in fertility is perceptible, towards earlier menarche, earlier age at first birth, increasing reproductive span and a slight increase in live births and surviving offspring, which is probably the result of a slow improvement in living conditions. The existence of birth control on the one hand, and a total fertility rate averaging six live births among the couples who do not practise contraception on the other, are other arguments.