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. 2010 Mar;21(1):39-61.
doi: 10.1007/s12110-010-9080-6. Epub 2010 Mar 9.

Optimizing Modern Family Size: Trade-offs between Fertility and the Economic Costs of Reproduction

David W Lawson, Ruth Mace

Optimizing Modern Family Size: Trade-offs between Fertility and the Economic Costs of Reproduction

David W Lawson et al. Hum Nat. 2010 Mar.

Abstract

Modern industrialized populations lack the strong positive correlations between wealth and reproductive success that characterize most traditional societies. While modernization has brought about substantial increases in personal wealth, fertility in many developed countries has plummeted to the lowest levels in recorded human history. These phenomena contradict evolutionary and economic models of the family that assume increasing wealth reduces resource competition between offspring, favoring high fertility norms. Here, we review the hypothesis that cultural modernization may in fact establish unusually intense reproductive trade-offs in wealthy relative to impoverished strata, favoring low fertility. We test this premise with British longitudinal data (the Avon Longitudinal Study of Parents and Children), exploring maternal self-perceptions of economic hardship in relation to increasing family size and actual socioeconomic status. Low-income and low-education-level mothers perceived the greatest economic costs associated with raising two versus one offspring. However, for all further increases to family size, reproduction appears most expensive for relatively wealthy and well-educated mothers. We discuss our results and review current literature on the long-term consequences of resource dilution in modern families.

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Figures

Fig. 1
Fig. 1
Family size and maternal perceptions of economic hardship. Increasing family size is associated with higher levels of economic hardship (for all contrasts, p < 0.001). Final model controls for time of measurement, mother’s age, partner’s age, father presence, household income, neighborhood quality, home ownership, social support score, social network score, ethnicity, and maternal employment (Table 2)
Fig. 2
Fig. 2
Incremental differences in economic hardship score as family size increases by socioeconomic strata: a caring for two children relative to one child, b caring for three relative to two children, c caring for four or more relative to three children. Higher socioeconomic status appears to reduce the trade-off between family size and economic hardship in the transition from one to two children. Above this threshold, middle- and high-socioeconomic-status families face the strongest trade-offs between family size and parental care. Final models control for time of measurement, mother’s age, partner’s age, father figure status, household income (education models only), neighborhood quality, home ownership, social support score, social network score, ethnicity, and maternal employment (Table 3). See text for confidence intervals
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References

    1. Barkow JH, Burley N. Human fertility, evolutionary biology, and the demographic transition. Ethology and Sociobiology. 1980;1:163–180. doi: 10.1016/0162-3095(80)90006-0. - DOI
    1. Becker GS, Lewis HG. Interaction between quantity and quality of children. In: Schultz TW, editor. Economics of the family: Marriage, children and human capital. Chicago: University of Chicago Press; 1973. pp. 81–90.
    1. Bentley G. Aping our ancestors: comparative aspects of reproductive ecology. Evolutionary Anthropology. 1999;7:175–185. doi: 10.1002/(SICI)1520-6505(1999)7:5<175::AID-EVAN3>3.0.CO;2-4. - DOI
    1. Bjerkedal T, Kristensen P, Skjeret GA, Brevik JI. Intelligence test scores and birth order among young Norwegian men (conscripts) analyzed within and between families. Intelligence. 2007;35:503–514. doi: 10.1016/j.intell.2007.01.004. - DOI
    1. Blake J. Family size and achievement. Los Angeles: University of California; 1989.

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