Evolutionary and Wealth Flows Theories of Fertility: Empirical Tests and New Models

Abstract

There were 3 study communities: 1) the northern Ache in the subtropical forests of eastern Paraguay. During 2 field sessions 1981-82 and 1984-85 the Ache spent their time on hunting-and-gathering treks foraging and at the mission with 200 inhabitants where they engaged in horticulture fishing hunting and gathering. Reproductive histories of a sample of 174 Ache women indicated total fertility rate of 8.15 prior to contact with the society at large; fertility increased in the 1980s following sedentarization. 2) The Diamante consisted of some 200 individuals of mixed but mostly Piro ancestry in southeastern Peru at the base of the Andes. The Piro practiced horticulture shotgun hunting fishing gathering and some wage labor. The total fertility rate of 27 women currently living in the community was 8.2. The behavioral data were collected from August 1988 to June 1989. 3) The Yomiwato consisted of 105 Machiguenga in southeastern Peru subsisting upon swidden horticulture bow-and-arrow hunting fishing and gathering. The total fertility rate of 22 women was 8.1. The data were collected from September 1988 to May 1989. The average Machiguenga child under the age of 18 consumed 2120 calories per day but produced only 500 calories daily during the period from birth to age 18. Machiguenga adults on the other hand produced caloric surpluses starting at about age 20. The average Piro child consumed about 2300 calories per day and produced only 370. The average adult over age 60 produced some 6600 calories but consumed only around 2500. On average Ache children consumed 2500 calories and acquired about 560 calories. These results have negative implications for Caldwells wealth flows hypothesis.