Evolution and the Demand for Children

Turke, Paul W.

doi:10.2307/1973405

Cited by 229 publications

(112 citation statements)

References 39 publications

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“…Some of these biological influences are, of course, not directly related to fertility desires themselves. Obviously, selection for sexual activity, for example, leads directly (even if not necessarily consciously) to fertility (e.g., Potts 1997;Turke 1989). Potts and Turke argued that a desire for copulation was sufficient, and that a desire to conceive has no particularly important role in understanding human fertility.…”

Section: Discussionmentioning

confidence: 99%

Multivariate Cholesky Models of Human Female Fertility Patterns in the NLSY

2007

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Substantial evidence now exists that variables measuring or correlated with human fertility outcomes have a heritable component. In this study, we define a series of age-sequenced fertility variables, and fit multivariate models to account for underlying shared genetic and environmental sources of variance. We make predictions based on a theory developed by Udry [(1996) Biosocial models of low-fertility societies. In: Casterline, JB, Lee RD, Foote KA (eds) Fertility in the United States: new patterns, new theories. The Population Council, New York] suggesting that biological/genetic motivations can be more easily realized and measured in settings in which fertility choices are available. Udry's theory, along with principles from molecular genetics and certain tenets of life history theory, allow us to make specific predictions about biometrical patterns across age. Consistent with predictions, our results suggest that there are different sources of genetic influence on fertility variance at early compared to later ages, but that there is only one source of shared environmental influence that occurs at early ages. These patterns are suggestive of the types of gene-gene and geneenvironment interactions for which we must account to better understand individual differences in fertility outcomes. KeywordsFertility; Fisher's theorem; FTNS; Heritability; Shared Environment; Multivariate models; Phenotypic plasticity; Hox genes; Life history theory Fisher's (1930) Fundamental Theorem of Natural Selection (the FTNS) has been misinterpreted by many researchers for many years. The traditional interpretation is that fitness traits and behaviors strongly affected by natural selection will "lose" their genetic variance in the long run. The implication is that fertility and fertility precursors should have little or no genetic variance, and thus zero heritability. This inference is correct if natural selection is the only process at work. But it is not. The FTNS has been interpreted by many to mean that, by definition, for fertility (and other traits related to fitness), h 2 = 0. But it does not. Hughes and Burleson (2000) suggested a number of different processes that re-introduce genetic variance into fitness traits, even while natural selection is washing it out. These include NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript mutation (the most important), frequency-dependent selection, heterozygote advantage (overdominance), sexual antagonism, and environmental perturbations. Fisher (1930) clearly did not intend or participate in this misinterpretation of the FTNS. In the same source in which he presented the FTNS, he also discussed the role of contraception (an environmental perturbation) in re-introducing genetic variance into human fertility (see also Houle 1992, for additional and more modern discussion of "perturbing forces" from the environment). Further, Fisher presented empirical data suggesting significant heritability in family size among the British aristocracy, h 2 = 0.40. Eve...

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Section: Discussionmentioning

confidence: 99%

Multivariate Cholesky Models of Human Female Fertility Patterns in the NLSY

2007

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“…Because the intensive data demands of our analysis required more detailed individual information than was available, we drew a random subsample of women from the HDSS for a tailored survey. Our sample included even numbers of women from (i) the ICDDR,B Area and the Government Service Area, and (ii) each of three 15-y age categories (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49), and 50-64), allowing for better representation of older women and 45 y of time depth regarding fertility and its correlates. Our final survey sample size was 944 women.…”

Section: Methodsmentioning

confidence: 99%

“…This relates to a broader finding (24,25) that when wealth is heritable, the costs of raising children increase, and fertility levels drop. Opportunity costs of raising children also increase in modern labor markets, especially for women (26)(27)(28)(29), who may intentionally reduce fertility to take advantage of new labor market opportunities [including those offered by microcredit or other programs designed to increase women's market participation (30)] or delay reproduction so long that their fertility is reduced by biological limits (31).…”

Section: Demographic Transition Theorymentioning

confidence: 99%

A model comparison approach shows stronger support for economic models of fertility decline

Shenk

Towner

Kress

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

118

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The demographic transition is an ongoing global phenomenon in which high fertility and mortality rates are replaced by low fertility and mortality. Despite intense interest in the causes of the transition, especially with respect to decreasing fertility rates, the underlying mechanisms motivating it are still subject to much debate. The literature is crowded with competing theories, including causal models that emphasize (i) mortality and extrinsic risk, (ii) the economic costs and benefits of investing in self and children, and (iii) the cultural transmission of low-fertility social norms. Distinguishing between models, however, requires more comprehensive, bettercontrolled studies than have been published to date. We use detailed demographic data from recent fieldwork to determine which models produce the most robust explanation of the rapid, recent demographic transition in rural Bangladesh. To rigorously compare models, we use an evidence-based statistical approach using model selection techniques derived from likelihood theory. This approach allows us to quantify the relative evidence the data give to alternative models, even when model predictions are not mutually exclusive. Results indicate that fertility, measured as either total fertility or surviving children, is best explained by models emphasizing economic factors and related motivations for parental investment. Our results also suggest important synergies between models, implicating multiple causal pathways in the rapidity and degree of recent demographic transitions.

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“…Hamilton's inclusive fitness theory is vital for explaining the reproductive behaviour of many species, such as social insects, and has recently been used as a framework for interpreting variation in human fertility at both the micro and the macro levels. It has been argued, for example, that the demographic transition from high to low fertility may have been partly caused by a decline in kin influence (Turke 1989;Newson, et al 2005). These authors speculated that during the process of -modernisation‖ kin networks fragment (see Ruggles (1994) for a debate on the extent of this process).…”

Section: What Effect Does the Kin Composition Of A Social Network Havmentioning

confidence: 99%

“…First, relatives can assist reproduction through the provision of resources and practical assistance (Turke 1989). In resource-scarce environments, providing economic resources or assistance could improve the health and fecundity of a relative, and thus may directly affect fertility.…”

Section: Proximate Mechanisms Through Which Kin May Influence Fertilitymentioning

confidence: 99%