Part four: Birth and survival patterns in numerically unstable proto agricultural societies in the Brazilian Amazon

Abstract

Demographic characteristics of eight diverse unacculturated tribes of Pará state of Brazil are examined. Serial censuses reveal highly unstable patterns and standard demographic procedures based on the assumption of a steady state are not applicable to current data. Postulating that prior to regular contacts with the national culture the population changes in the several tribes were asynchronous, we have used the average of the several tribes as reconstructed for the period prior to 1960 as a basis for analyses. These data indicate that fertility regulation was more important than mortality in determining the selective potential. Variance in male fertility in polygamous tribes was much greater than variance of female fertility or male fertility in monogamous tribes. In general, fertility and mortality rates in the Pará tribes were more like other Brazilian tribes and the !Kung of Africa than like the Yanomama of Venezuela.