Resumo

LANZA, Norberto  e  VALEGGIA, Claudia. La modernización ¿Siempre disminuye la fecundidad? Análisis de la transición demográfica en una Población Toba. Rev Arg Antrop Biol [online]. 2012, vol.14, n.1, pp.33-43. ISSN 1514-7991.

According to the evolutionary theory, all behaviors should be considered adaptive, i.e., they help to maximize the reproductive success of this actor. However, reproduction involves a cost; thus, natural behaviors that maximize the relationship between the production of offspring and parental investment would be selected. However, this relationship is shaped by the environmental constraints. On the other hand, the classic theory of demographic transition argues that improvements in living conditions in a given population, determine a decrease in fertility. Can this observation be explained in evolutionary terms? The population of aboriginal Tobas from Argentina are undergoing a deep economic and social transition, characterized by a greater availability of material resources. The aim of this study was to evaluate the effect of these socioeconomic changes on several demographic parameters in a population of western Tobas from the province of Formosa, Argentina. This work estimated the Total Fertility Rate (TFR) and age-specific fertility rates (fx) of four periods, between 1981-1999. Our results had shown increasing trends of TFR changing between 6.36 and 7.27 children. The peak of fertility changed first to older ages and then changed back to younger ages also. It is proposed that this increase in fertility would be determined by a decrease in maternal reproductive costs, which would be the result of increased access to energy resources. However, these costs can vary with maternal age, affecting the age structure of fertility.

Palavras-chave : Aboriginal demography; Biodemography; Formosa; Reproductive costs.

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