The Biodemography of Modern Women: Tradeoffs When Resources Become Limiting

Abstract

Life history theory postulates tradeoffs of current versus future reproduction; in both developed and developing nations today, women face evolutionarily novel versions of these tradeoffs. Here we use a nonlinear dynamic model to explore: [1] the general issues of tradeoffs of education, work, and current fertility; [2] some specific examples (e.g., what increase in fertility will compensate for particular delays of age at first birth under given conditions). Finally, we model a largely unrecognized issue. Demographic transitions of the past have been characterized by decreases in fertility accompanied by (sometimes quite large) increases in per capita investment in offspring. The Rio Conference and its followup highlighted the conflicts between low-fertility, high-consumption, versus highfertility, lower consumption strategies — yet we have few ways to make testable predictions about future conflicts. We explore outcomes when impending resource constraints differentially affect short-generation-time-strategists, versus delayed-reproduction-resource-acquirers. The conditions favoring delayed fertility with resource accumulation are highly constrained; under almost all conditions reproduction in the early 20s leads to the greatest lineage success for women in the models.