This argument forms an important facet of what is usually referred to as parental investment (PI) theory, a subset of life history theory. To test the hypothesis that parents experiencing resource constraints will invest differentially in offspring, and that the patterns of investment accord with PI theory, a number of health, nutrition and social variables were measured for all children between the ages of 5 and 15 living in a Yanomamö village on the Upper Orinoco River in southern Venezuela. The Yanomamö are Native American swidden horticulturists living in the tropical forests of southern Venezuela and northern Brazil. They number approximately 15–20,000, and live in 200–250 widely scattered.
