A friend gave some very high praise to The History of Fertility Transitions and the New Memeplex, and so it has been sitting amongst my Chrome browser tabs for a month or more. Last week, I read it, and it really is a very important, big-picture article. The basic idea is that memes compete via cultural transmission in much the same way that genes compete via biological transmission.1 Historically, memes have been transmitted primarily through intergenerational transfer, which has given a strong advantage to cultures with high fertility. If you have more kids, and if the main way to pass on memes is to kids, than successful cultures are those that have lots of kids.
The advent of the printing press and other technological advancements turbocharged an alternative method of meme reproduction however: cultural diffusion. Now memes didn’t have to depend on having lots of children to carry them on. They could also be transmitted laterally in books.2 This resulted in a break between biological and cultural evolution, and it allowed cultures with low fertility to compete successfully by “infecting” other cultures with the meme for lower fertility.
Accordingly, there was a massive cultural transition that started in the 18th century with the American and French Revolutions and has since engulfed the entire world: all countries and regions in the world either already practice controlled fertility or are transitioning from uncontrolled / natural fertility to controlled fertility. At an individual level, this makes sense because it allows families to invest more resources per child, especially in education. And education is the key to maintaining and increasing social status. So the first consequence is a drastic reduction in the fertility rate. In many developed nations, the fertility rate3 is already far below replacement. The second consequence is that the eugenic effects of natural fertility (in which couples with high intelligence and self-control have more children) have been replaced by dysgenic effects (in which couples with high intelligence and self-control have fewer children.) As the article puts it:
The benefits of the new pattern are increased material wealth per person, a reduction in disease, starvation, and genocide, and upward social mobility. The main drawback is the onset of a dysgenic phase that may end civilization as we know it.
The article is most impressive for the exhaustive, meticulously researched evidence that the transition has, in fact, occurred.4 It doesn’t do as good a job at talking about the consequences of this transition, however. The dysgenic effect is not the only problem, and may not even be the most acute one. I happen to have recently watched a YouTube documentary about the demographic winter being created by declining fertility rates. It’s a demographic winter because, as fertility rates fall rapidly, the average age of a population rises dramatically. You still have all the old folks (from prior decades when fertility was higher), but there are far fewer children to replace them. As a result, children become relatively scarce.
This isn’t just sad. It’s very, very dangerous. Some of the most obvious problems have to do with entitlements for the elderly. When you have a huge population of old, retired folks and a much, much smaller population of active workers, this is bad. It gets much worse when you factor in immigration, since the racial characteristics of the two groups may be significantly different as well. In the United States, for example, you’ll have a lot of young Hispanics paying taxes to support retired whites. You’ll get a similar problem in Europe, with African and Middle Eastern immigrants taking the place of Hispanics.
Another point made by the documentary, and a plausible one, is that the economy tracks population with about a 48-year lag. The idea is that what really determines the stock market and overall economic performance is consumption, and people hit their peak consumption at about age 48. So when you have a very large cohort hit age 48, you get an economic boom. If the successive generations are much smaller, you will get economic contractions.5
This might seem counterintutive. Aren’t more people a drain on resources? No, not necessarily. As this fascinating Wall Street Journal article outlines:
An odd thing about people, compared with other animals, is that the more of us there are, the more we thrive. World population has doubled in my lifetime, but the world’s income has octupled. The richest places on Earth are among the most densely populated.
Economic growth depends on the creative energy that comes from lots of people trading ideas in densely populated clusters. If population density declines, so too will economic and scientific progress.
Of course, the biggest argument in favor of limited population is environmental. Don’t more people take up more resources? But there’s a major problem with this criticism as well, which is that the unit of interest is not really individuals but rather households. In other words, if you have a situation where you’ve got 10,000 households and each has 4 people (for a total population of 40,000) and another situation where you’ve got 20,000 household and each has 2 people (for a total population of 40,000), then it’s pretty obvious that the population with more households is going to use up a lot more resources. Of course there is still a maximum aggregate population that the Earth can sustain, but the point is that the resource savings from low fertility are going to be much, much less than you might initially think.
Looking ahead, I think the best case scenario is that we manage to survive the coming demographic contraction without some kind of horrific World War III followed by Mad Max scenario. But, ultimately, the aggregate fertility rate really needs to remain at replacement rate levels. Otherwise, we’re looking at the possibility of species suicide. Frankly, however, I would prefer that we see the return of positive population growth in the future coupled with some serious attempts at extra-planetary colonization. It is the nature of life to grow. I don’t believe stagnation is a long-run solution.