Offspring Human Fertility Behavior in Biodemographic Perspective (2003) / Chapter Skim
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1. Biodemography of Fertility and Family Formation
1. Biodemography of Fertility and Family Formation
Pages 1-17
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From page 1... ...
But demographers are only beginning to assimilate findings and approaches from behavioral genetics, molecular genetics, neuro-endocrinology, and cross-species life history analysis and to place them in the context of evolutionary theory. With support from the National Institute of Child Health and Human Development, the National Research Council's Committee on Population has brought together an interdisciplinary group to review this young field of science and reflect on promising opportunities for future research.
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From page 2... ...
Students of longevity work with a definitive outcome death. That contrasts with the many outcome measures and intermediate processes of transition summed up under a general heading like "Fertility Behavior" or "Family Formation." The biodemography of longevity has been channeled in particular directions by a set of initiating discoveries, measurements of hazard curves tapering at extreme ages in Mediterranean fruit flies, Drosophila, and nematode worms.
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From page 3... ...
Along with data opportunities, the different branches of biodemography share a reliance on evolutionary theory and on the clues to the human evolutionary environment that anthropology provides. Reproductive fitness in the face of natural selection is measured as a joint function of age-specific rates of survival and fertility.
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From page 4... ...
These are followed by treatments based on evolutionary theory and anthropology, rounded out by perspectives from economic and social demography. BEHAVIORAL GENETICS In Chapter 2, Michael Rutter begins with an overview of what is being learned and what can be learned from behavioral genetics about genetic influences on fertility.
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From page 5... ...
Chapter 3 by Kohier and Rodgers provides an illustrative case study of how current behavioral genetic approaches are being applied in practice to fertility behavior. (A fuller set of examples is found in Rodgers, Rowe, and Miller t20001 and Rodgers and Kohier t20021.)
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From page 6... ...
They dovetail with approaches for making use of biological indicators of hormonal and other physiological responses, as described in the National Research Council's 2000 volume Cells and Surveys, already mentioned. Such measures are particularly relevant for studies of fertility behavior, since hormonal signaling must play a role in so many pathways of influence.
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From page 7... ...
The prairie voles that form pair bonds have occurrences of a particular sequence of 420 base pairs of DNA in their version of the gene, as compared to their neighbors, the montane voles of the Rocky Mountain states, which do not form pair bonds. The full account, involving the hormone oxytocin in females as well as vasopressin in males, reads like a detective story.
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From page 8... ...
For the biodemography of fertility, Cameron points to several priorities for interdisciplinary research. One involves effects of extensive artificial exposure to steroids and other endocrinologically active substances now occurring in developed societies through medication, self-medication, and consumer choice.
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We ask not only what a gene produces in the body but also where it comes from out of prehistory. For human fertility behavior,
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Kaplan and Lancaster's chapter is representative of a line of thought in which a kind of economic calculus takes its place alongside the traditional reproductive calculus in the reckoning of long-term fitness in the face of natural selection. This economic calculus involves constraints imposed by feasible age-specific production and consumption, returns to skill, social support, and resource transfers across generations.
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From page 11... ...
Campbell reflects on the evolutionary trade-offs implicated in this part of the human developmental program, on the gap in years between puberty and procreation in many human societies, and on the reversed order of peak growth spurt and menarche for girls compared to puberty and peak growth for boys. He considers refinements of the basic idea that timing of sexual maturation balances the benefits of earlier reproductive opportunities against the costs of risky male-male competition.
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From page 12... ...
In Chapter 11, David Lam explores intersections between rational choice models from economic demography and evolutionary approaches to human fertility transitions. Two fertility transitions are at stake the classic "demographic transition" to near-replacement fertility still under way in many developing countries and the recent transition to below-replacement fertility most visible in a number of European nations.
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From page 13... ...
The biological factors discussed in this volume interact with a broad range of environmental demographic determinants, economic trade-offs, tastes and preferences, gender roles, the calculus of self-interest and joint interest, societal support, and future security. Granting parallels between this framework and behavioral ecology and life history analysis, Hobcraft describes the challenges facing a research agenda for uncovering genetic and neuro-endocrine substructures for fertility behaviors that are now so largely matters of conSClOUS C" Dolce.
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From page 14... ...
This term may stand as short-hand for some of the larger issues through which the biodemography of fertility behavior and family formation impinges on the practical demography of policy forecasts. The question makes sense when our evolutionary heritage is viewed not as a built-in program of behavioral directives but as a sounding-board for responses to ever-changing environmental stimuli.
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From page 15... ...
Both evolutionary theory and endocrinological investigations presented, for example, in Chapters 8 and 9 suggest that traits implicated in family formation outcomes, like risk-taking, may be more amenable to genetic analysis than fertility outcomes themselves. Separating genetic influences from self-selection may be aided by accumulating longitudinal data sets like the Add Health Study.
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From page 16... ...
Making genetics, neuroendocrinology, integrative biology, and evolutionary perspectives accessible to demographers may be a larger challenge. But the chapters of this volume illustrate the extensive common ground that already exists around the study of fertility behavior and family formation and the promise of future cooperative biodemographic research.
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From page 17... ...
2000 Genetic Influences on Human Fertility and Sexuality: Theoretical and Empirical Contributions from the Biological and Behavioral Sciences. Boston: Kluwer Academic Publishers.
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