The Economist’s Free Exchange column drops in on the question of an economic motherhood penalty from childbirth. It is nice to see that the Economist correctly distinguishes between two distinct economic motherhood penalties, both of which can be traced to the interplay between evolutionary forces and modernity, where the latter in this case is defined as an environment with rapidly increasing returns to investment in human capital and education. The first, between fathers and mothers, emerge because the cost of child-rearing especially in the early part of a child’s life overwhelmingly falls on the mother, a conclusion which follows from Trivers (1972). This is true in terms of the cost during pregnancy and immediately after too. It is also true before we consider the possibility that the resource allocation trade-off for many women shifts in the wake of motherhood. The second motherhood penalty occurs between women. Put simply, in an economic structure where childless women have the ability to devote all their resources to somatic investment and take advantage of the above-mentioned increasing returns to human capital investment, the wage and wealth divergence between women who have many children and those who have none will widen significantly, at least in theory. For more on this, I cover the theory in more detail in my essay on fertility and sexual selection; see here.
Read MoreMarkets are moving, and I’ll have more to say about that in due course, but we before we get to that, I am finally ready to present the third chapter in my running demographics project. The landing page for the project can be found here. You can get the PDF for the third chapter below, or via the landing page.
This chapter kicks off the description, analysis and discussion of fertility and birth rates. It is the first of, I suspect, three chapters on fertility. In it, I try to cover three bases. First, I cover the basics, defining the different ways in which fertility and birth rates are described quantitatively in the literature, and the distinction between these terms. Secondly, I summarise the stylised facts about the global fertility transition, when it began, and how it is going. My objective has been to strike a balance between the big picture and sufficient detail to allow for the discussion individual case studies across individual nations, or groups of countries. The key point, from both an empirical and theoretical perspective, is that fertility does not stabilise at replacement levels in the final stages of the demographic transition. In this way, the fertility transition is an ongoing phenomenon, in contrast to the picture painted by the stylised model of the demographic transition. Thirdly, I run through the theory of sexual selection as described by Trivers (1972), and used in Richard Dawkins’ seminal, The Selfish Gene. There are two reasons for this. First, the basics matter. The game of mate selection, which feeds through to how parents share the costs of reproduction and child-rearing, is crucial to understand why births occur in the first place. The idea that evolved behaviour described by Trivers (1972) can be used to explain phenomena in a modern context invites us to heed F. Scott Fitzgerald’s advice that “the test of a first-rate intelligence is the ability to hold two opposing ideas in mind at the same time and still retain the ability to function.” It is reasonable to expect that many phenomena observed in a modern society can be traced back to core evolutionary processes. But equally, it is unreasonable to go searching for an evolutionary explanation for every phenomenon that social scientists might be interested in, in a modern economy. Whatever the balance between these two positions, the link between modern behaviour and pre-modern evolutionary theorems is a constant source of debate and controversy in the literature on demographics and fertility.
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