FERTILITY AND LABOR SUPPLY IN FEMINA-ECONOMICA

This paper sets out a formal framework for the biological-evolutionary study of human economic behaviour. Femina economica is a hypothetical parthenogenetic species with a simple economy. Individuals make decis ions about labour supply and fertility subject to time and resource co nstraints. Labour is of differing types and a parent determines the ty pe of her offspring's labour. Wages are determined as marginal product ivities from an economy-wide production function. Three propositions a re proved, of which the first shows that under very general conditions there exists a population genetic equilibrium, in which individuals' decisions are assumed to be under genetic control. The second shows th at at a population genetic equilibrium, individuals have the same beha viour as they would at an economic equilibrium, in which individuals a re assumed to maximise a common utility function. The third propositio n shows that if the common utility function fulfils certain conditions , the attainment of an economic equilibrium brings about the same beha viour as a population genetic equilibrium. This suggests a way in whic h evolutionarily stable behaviour can be brought about without the nec essity for changes in gene frequencies. Demographic implications inclu de the possibility of interpreting in Darwinian terms the reductions i n offspring number that occur in fertility transitions, and the weak o r even negative correlation in economically developed societies betwee n control of resources and offspring number. There are implications fo r economics of deriving utility maximisation from population genetics. (C) 1998 Academic Press.