In this essay. I suggest that the crisis in our understanding of fertility transitions is more apparent than real. Although most existing theories of fertility transition have been partially or wholly discredited, this reflects a tendency to assume that all fertility transitions share one or two causes, to ignore mortality decline as a precondition for fertility decline, to assume that pretransitional fertility is wholly governed by social constraints rather than by individual decision-making. and to test ideas on a decadal time scale. I end the essay by suggesting a perceptual. interactive approach to explaining fertility transitions that is closely allied to existing theories but focuses on conditions that lead couples to switch from postnatal to prenatal controls on family size.

Explaining fertility transitions

A cap on greenhouse gas emissions makes total emissions a fixed common-property resource. Population increases under a cap are therefore self-limiting: a population increase raises labor and reduces emissions per unit of labor, which lowers incomes and fertility. Because a marginal birth under a cap lowers all incomes, a cap induces a negative population externality. The externality is substantial in calibrations, about 20 percent of income in steady state and 5 percent of income immediately after imposition, or more, per child. Similarly, the optimal population may be one-quarter of the natural population in steady state.

https://www.econstor.eu/bitstream/10419/38939/1/627025455.pdf

Population under a cap on greenhouse gas emissions

Advances in agriculture and food systems, consequent increases in food availability, and a shift in dietary consumption patterns with economic development and urbanization of developing societies leads to adverse health outcomes. The structure of the habitual diet is altered and is characterized by increasing consumption of fats, saturated fats largely from animal sources and sugars. Lifestyle changes in an increasingly urbanized environment which occurs concurrently contributes to a reduction in physical activity levels which promotes overweight and obesity. The essence of these changes is captured by the term ‘nutrition transition’ which accompanies the demographic and epidemiologic transition in these countries with economic development. The existing burden of undernutrition in developing countries is thus compounded by the adverse effects of the nutrition transition, notably the increasing prevalence of obesity and non-communicable diseases. This double burden of malnutrition adds to the health and economic burden of developing societies.

Nutrition transition and its health outcomes.

the first demographic transition started in many western industrialized societies around the latter part of the nineteenth century with steady mortality improvement. expectation of life at birth, about 40 years at the start of the transition, has now doubled (riley 2001). Fertility declined from a level of about five children to under two children per woman over the same period (Coale and watkins 1986; Chesnais 1993; dyson 2010). this decline was interrupted in many industrialized countries by the baby boom and associated marriage boom in the post–world war ii period, peaking in the early 1960s. the decline resumed to such an extent that some countries experienced ultra-low fertility, with total fertility rates below 1.3, together with very low rates of marriage (Billari and Kohler 2004; Frejka et al. 2008). widespread signs of stabilization or reversal from these historically unprecedented low fertility levels only started to appear in the early twenty-first century (Goldstein, Sobotka, and Jasilioniene 2009). these widespread fertility declines have led to population aging, initially resulting from reductions in fertility and more recently compounded by mortality improvement at older ages. while countries have shown some variations in the timing and magnitude, broadly similar trends are observed. trends in fertility and life expectancy for the country that is the subject of this chapter, england and wales (hereafter Britain), are shown in Figures 1a and 1b. this resumption of fertility decline in the second half of the twentieth century was associated with changes in partnership behavior in many countries that some consider to be a second demographic transition (van de Kaa 1987; lesthaeghe 1995), although this contention has been challenged , (e.g., Coleman 2005). these changes included substantial reductions in marriage and increases in marital breakdown. nonmarital cohabitation

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1728-4457.2011.00378.x

Long-term effects of the demographic transition on family and kinship networks in Britain.

Fundamental cause theory posits that social inequalities in health arise because of unequal access to flexible resources, including knowledge, money, power, prestige, and beneficial social connections, which allow people to avoid risk factors and adopt protective factors relevant in a particular place. In this study, we posit that diseases should also be put into temporal context. We characterize diseases as transitioning through four stages at a given time: (1) natural mortality, characterized by no knowledge about risk factors, preventions, or treatments for a disease in a population; (2) producing inequalities, characterized by unequal diffusion of innovations; (3) reducing inequalities, characterized by increased access to health knowledge; and (4) reduced mortality/disease elimination, characterized by widely available prevention and effective treatment. For illustration, we pair an ideal-types analysis with mortality data to explore hypothesized incidence rates of diseases. Although social inequalities exist in incidence rates of many diseases, the cause, extent, and direction of inequalities change systematically in relation to human intervention. This article highlights opportunities for further development, specifically highlighting the role of stage duration in maintaining social inequalities in cause-specific mortality.

/pdf/a-social-history-of-disease-contextualizing-the-rise-and-2gy0wj9af4.pdf

Philip Kreager

Papers

The Demographic Transition: Stages, Patterns and Economic Implications. A Longitudinal Study of Sixty-Seven Countries Covering the Period 1720-1984