The Polygyny–Fertility Hypothesis: A Re-evaluation

Abstract
Previous studies of the relationship between polygynous marriages and fertility have produced mixed results, although on balance evidence suggests that fertility levels are lower in polygynous than in monogamous marriages. It is argued that the inconsistent results stem from the aggregation of fertility data among all wives in polygynous unions, and that major differences are due to variations in fertility by wife-order and number of wives in polygynous unions. Data for 2534 polygynists with 7378 marriages are analysed and contrasted with fertility data from once married women, using information covering population of Utah during the nineteenth century. Our data indicate significant variations in fertility levels by wife-order; these fertility differences are largely due to variations in length of exposure to the risk of conception and birth intervals.