A representational picture of a newborn baby.
Credit: iStock Photo
By Justin Fox
For most of human history (and probably prehistory), higher male status was linked to having more children. This relationship between positive status and offspring seems to have reached its peak with despotic rulers such as reputed father-of-thousands Genghis Khan — a 2003 genetic study found that one out of every 200 men worldwide may carry his Y chromosome. For women, that level of fecundity was of course impossible, and overall their status-offspring link was weaker, but in general people with more resources had more children.
Then, in the 18th century, the situation began to change. In countries at the forefront of the Industrial Revolution, and the revolutions in living standards and life expectancy that followed, birth rates fell. Within these increasingly wealthy countries, it was the affluent and educated — with education becoming a key marker of status — who led the way in reducing family size.
In the 20th century, this new inverse relationship between affluence/status and fertility became an established fact. Creepy ideologies such as eugenics and “Great Replacement” theory grew up around fears that the wrong sort of people were doing most of the reproducing. Economists struggled to explain why such an exception to the rule that wealthier people can afford more stuff persisted. Other scholars argued that evolutionary theories no longer applied to humans because they had stopped following a basic rule of evolution.
Well, it’s back to the drawing board. Researchers have been finding more and more evidence that, among and within countries that have already passed through what’s generally called demographic transition, the old, positive relationship between status and affluence on the one hand and number of children on the other is beginning to reestablish itself.
Just beginning, mind you: Compare fertility rates — expressed here as estimated lifetime births per woman — to per-capita gross domestic product in all 191 countries and territories for which the World Bank has recent data on both, and there’s still a pretty strong negative correlation (negative 0.6 out of a maximum of negative 1) between affluence and births.
Representative of fertility rates to GDP per capital from 2017-2021.
Credit: Bloomberg
The picture changes when you restrict the view to Europe, where the demographic transition is more or less complete. The correlation drops to effectively zero, and if you remove tiny Luxembourg (population 640,000), it rises to weakly positive (correlation coefficient of 0.2).
Income-birth relationship in Europe.
Credit: Bloomberg
Within developed countries, there’s now generally a positive relationship between men’s income and education level and fatherhood. In a US Census Bureau survey conducted in 2014, 70.1 per cent of men with graduate or professional degrees had children while only 48.8 per cent of those without a high school diploma did. In the US, the overall relationship between income/education and births remains negative for women (for whom the most recent data are from 2022), but among White, non-Hispanic women the curve is becoming U-shaped, with those with bachelor’s degrees or higher having more kids than those with some college. In parts of Europe, the transformation is even further along: A 2022 study by Stockholm University demographer Martin Kolk found a modestly positive gradient between accumulated lifetime income and number of children for Swedish women born in 1960 and later.
Two recent syntheses offer useful and readable overviews of current research. In Not So Weird After All: The Changing Relationship Between Status and Fertility, a book out this month, sociologist Rosemary L. Hopcroft of the University of North Carolina at Charlotte and anthropologists Martin Fieder and Susanne Huber of the University of Vienna look at the evolutionary background and implications of the change, while in the The economics of fertility: a new era, published as a book chapter last year but also available as a paywall-free working paper and 1,200-word executive summary, economists Matthias Doepke of the London School of Economics, Anne Hannusch and Michèle Tertilt of the University of Mannheim and Fabian Kindermann of the University of Regensburg present recent empirical findings and offer possible economic explanations for what’s going on.
One clear takeaway is that the inverse relationship between affluence and babies has been a byproduct of affluent nations and people embarking on the demographic transition first, so it shouldn’t be surprising to find post-transition behavior reverting to earlier patterns. “Modern societies are much less anomalous to preindustrial societies than once thought,” write Hopcroft, Fieder and Huber. The “Weird” in their title is a reference to the acronym for inhabitants of Western, educated, industrialized, democratic nations, coined in a 2010 paper critiquing the heavy reliance of social scientists on experiments conducted among such globally anomalous people, then used by one of the paper’s co-authors, Harvard anthropologist Joseph Henrich, to explain the rise of the West in his 2020 book, The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous. Maybe Westerners have just been going through a phase.
Figuring out the fertility rules of the post-demographic-transition era is what economists are most focused on, with the Doepke-Hannusch-Kindermann-Tertilt paper paying lots of attention to gender dynamics. While the growth in career and educational opportunities for women drove fertility declines in the past, there are signs — mainly from the Nordic countries — that accommodating women’s career ambitions might be essential to staving off further declines. One intriguing chart from the paper, which I have reproduced here, shows that among a sample of advanced economies, those where men take on more housework and child care responsibilities have higher fertility rates.
Household work's correlation with fertility rates.
Credit: Bloomberg
The economists found similar if weaker links between fertility and female labor-force participation and public spending on early childhood education (aka child care). As wealthy countries increasingly fret about falling birthrates, this offers an appealing roadmap — if perhaps a hard-to-execute one in places where it goes up against social norms. The future of demographic success may look less like Genghis Khan and more like dads who do the laundry.