Alpha.Sources — Alpha Sources.CV

Fertility and sexual selection

Markets 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.

Mere Mortals no Longer?

The evolution of mortality through the demographic transition is as close as we come to a deterministic process in the analysis of population dynamics. Science and technology have become increasingly better at keeping people alive, a benefit that still seems to drive the human experience to this day. It’s possible to identify milestones through history such as the development of modern sanitation to defeat contagious air- and waterborne illnesses, the development of vaccines for specific illnesses, as well as overall technological development in the field of healthcare. It is a story about pinning down the causality between rising national income and technological development and the improvement in the human living condition in the past 250 years. Researchers still debate the relative importance and merits of specific drivers, but it’s possible to generalize, all the same. The story about of human mortality is contained in a few relationships, for the individual, between, and possibly within countries. It is a story about Nike swoosh-shaped, logarithmic and asymptotic curves, and the extent to which we observe deviations from such stylized relationships over time, and why.

The Balance of Payments

The flow of goods and capital across borders and between nations has featured in human storytelling and economic relations since the beginning of time. The biblical protagonists traveled and traded with each other, and often fought over the dominion of resources. The protagonists in modern historical tales of trade and war since the turn of the millennium continue the habit in similar ways. You would be hard-pressed to find a better historical account of that than in Ronald Findlay and Kevin H. O’Rourke’s Power and Plenty. The book is as much about the wars that divided empires and nations as it is about the exchange of goods and capital that bound them together, though it is reasonable to say that these two perspectives are joined at the hip. Economics plays a specific role in the study of global trade and empire-building. The exchange of goods, capital, and services across borders gives rise to transactions as the ownership of resources shifts. Over time, these processes lead to the accumulation of wealth and debt on the part of nations and economic actors—assets and liabilities, in the jargon of modern finance. It is the economist’s job to trace, identify, and record the nature and value of these transactions.

It's the fertility, stupid

Seven years ago I did a thesis on demographics and capital flows, which informs my thinking on economics and finance to this day. That’s a long time ago, though, so I thought that I would provide an update on one of the key pillars of that work. It starts with ageing. The breadth and speed of population ageing currently sweeping the global economy is unprecedented in human history. It is partly driven by rising life expectancy, which we can crudely hold to be a linear function of economic development. But it is also a result of a complex fertility transition. Two stylised facts should be highlighted at the outset. Firstly, the demographic transition does not end with a homeostatic “equilibrium” of replacement level fertility. Secondly, the decline in fertility seems to be driven by two forces; the quantum effect which operates on a quantity/quality trade-off and the tempo effect, which is the phenomenon of “missing births” as women postpone having their first child. The two are connected in complex ways, that we probably don’t quite understand. My goal here is to understand what is happening to global fertility rates. My sample is the World Bank’s data and their estimates of total fertility rates across countries.

02

Alpha Sources Blog