Why Do Women Have More Children than They Want? Understanding Excess Fertility in Bolivian Amerindians

Lisa S. McAllister, University of California, Santa Barbara
Michael D. Gurven, University of California, Santa Barbara

Many Amerindian populations are experiencing rapid population growth with fertility greatly exceeding stated ideal family sizes (IFS). We test, among Tsimane Amerindians, three hypotheses for why IFS may be exceeded, despite socioeconomic development: (H1) limited female reproductive autonomy; (H2) improved maternal condition without effective fertility control; (H3) low perceived returns on investments in embodied capital. We test these using reproductive histories and prospective fertility on 521 Tsimane, and semi-structured interviews from 76 women. Analyzes used include multiple regression, t-tests and ANOVA. Of the hypotheses, H3 received the most support. There is little overt motivation to pursue education and delay reproduction. Many members of small-scale populations may exceed their IFS due to the low perceived or real benefits of investing novel forms of human capital in self and offspring. Somatic wealth and large kin networks may persist as the most important components of social success, and so fertility remains high.