Evolutionary Demography and Intrahousehold Time Allocation: School Attendance and Child Labor Among the Okavango Delta Peoples of Botswana JOHN BOCK Ã Department of Anthropology, California State University, Fullerton, California ABSTRACT The ways in which resources are allocated within households and/or families, es- pecially within the context of childrenÕs time allocation to labor and schooling, has long been a subject of concern to demographers and economists. Differential investment in children and resulting dif- ferences in activity budgets may have significant effects on childrenÕs growth and development as well as on aspects of reproduction. This study uses predictions regarding parental investment in the embodied capital of offspring generated by evolutionary theory to examine the pattern of childrenÕs time allocation to labor and schooling among the Okavango Delta Peoples of Botswana. Models incorporating individual costs and benefits of resource allocation, conflicts of interests between men and women and between parents and offspring, and the effects of family composition, subsistence ecology, and gender are developed and applied to data on time allocation, household demography, and household economy. Several findings emerged: (1) The availability of alternative productive tasks strongly affects intra- and intergenerational labor substitution. (2) The presence of similarly aged children of the same sex within the household decreases the likelihood of both boys and girls engaging in a specific productive activity and increases the likelihood of childrenÕs school attendance. (3) Birth order, the labor needs of the household, and parentsÕ marital status all affect school attendance. These results have implications for understanding the determinants of childrenÕs time allocation to labor and schooling and consequent impacts on development, health, and welfare. Am. J. Hum. Biol. 14: 206–221, 2002. Ó 2002 Wiley-Liss, Inc. The ways in which resources are allocated within households and/or families, espe- cially within the context of childrenÕs time allocation to labor and schooling, has long been a subject of concern to demographers and economists (Cain, 1978, 1980; Caldwell, 1976; Grootaert and Patrinos, 1999; Haddad et al., 1997; Kimhi, 1996; Mueller, 1976; Nag, 1972, 1981; Nag et al., 1978; Skoufias, 1993; Udry, 1996). Policy makers recognize that variation in childrenÕs time allocation across societies has major implications for societal productivity and human capital, gender equality, and child health and wel- fare (see Udry, 1996). Of particular interest to human biologists are the ways in which differential access to resources within the household and variation in activity budgets impact growth and development of children. Evolutionary theory generates models of intrahousehold resource allocation, which provide new insights and perspectives on these issues. This paper uses data on chil- drenÕs school attendance and labor among the Okavango Delta Peoples of Botswana to examine intrahousehold resource and time allocation from an evolutionary perspective. Evolutionary theory and interindividual conflicts Modern biology recognizes that adapta- tions are the result of non-random differ- ential reproduction of individuals due to the action of selection on phenotypes (Hamil- ton, 1964; Williams, l966). Because it is these individual differences in reproduction and in phenotype-design that produce ad- aptations, evolutionary approaches to pop- ulation focus on the effects of individual behaviors and outcomes rather than exclu- sively on population-level phenomena (Low, 1993). Rather, population-level character- istics are the result of feedback between these individual micro-level events and macro-level processes (Hill, 1993). These macro-level processes include not only fea- tures of the physical environment but also Contract grant sponsors: LSB Leakey Foundation: General Grant 1992, General Grant 1994; Contract grant sponsors: NSF: BCS 9107587 (to Henry Harpending and Jeffrey Kurland). Ã Correspondence to: John Bock, Dept. of Anthropology, Cali- fornia State University, PO Box 6846, Fullerton, CA 92834- 6846. E-mail: jbock@fullerton.edu Received 12 February 2001; Revision received 28 September 2001; Accepted 5 October 2001 AMERICAN JOURNAL OF HUMAN BIOLOGY 14:206–221 (2002); DOI 10.1002/ajhb.10040 ª 2002 Wiley-Liss, Inc.