ABSTRACT
The Ache age-sex structure is much more similar to that reported for the Yanomamo in the 1960s, with both populations showing evidence of rapid growth and male-biased sex ratios. A comparison with the 1970 population suggests that contact-related epidemics killed many children of both sexes under the age of ten, and a high proportion of adults of both sexes over the age of forty. The resultant age-sex pyramids show a rapidly growing population with a male-biased sex ratio before contact and an increasingly female-biased sex ratio since contact. The age estimates thus derived are independent of any assumptions about such demographic parameters as age at specified parity, but they do require that individuals reliably report differences in age. Despite the elegance with which Howell was able to derive age estimates for the !Kung population, there are a few disadvantages associated with this method for estimating age.
