If constraints of wealth and health ever become dramatically reduced, would fertility rates still remain below replacement levels?
The world’s fertility rate has fallen to about 2.4. In the next few years it may reach replacement levels (~2.1) outside of Sub-Saharan Africa, where it is an estimated 4.7 but falling quickly. Even some of the most conservative of wealthy societies, such as American Mormons or Gulf-monarchy Arabs or religious (but not Orthodox) Israeli Jews, are approaching or have already reached replacement levels.
Many countries, whether high-income or medium-income, now have fertility rates as low as 1-1.5. No countries are yet below 1, but a few, notably South Korea at 1.09, are getting very close. Fertility rates in the US and Brazil are both around 1.7. In Japan and much of Europe they are around 1.4. China’s fertility rate is probably somewhere between 1.1-1.7, down from 2.7 when it began its one-child policy in 1979. India’s is roughly 2.2, down from 5.2 when its own mass sterilization program began in 1975. Northeast China, China’s rust belt, a region of 110 million people, has a fertility rate of 0.55!
To a certain extent, the relationship between high income and low fertility has begun to break down. Northeast China, a relatively poor part of what is still a relatively poor country, is only the most extreme example of this. Many of the world’s medium-income and low-income countries now have fertility rates that are nearly as low as, or lower than, those in rich countries. With the exception of Sub-Saharan Africa and a few small Pacific island states like Samoa, only two countries, Afghanistan and Yemen, remain above a 3.5 fertility rate.
Even in Africa 16 countries’ fertility rates have fallen below 3.5. Ethiopia, the second most populous African country, is at 3.9. By far the world’s biggest outliers are Nigeria at 5.2 and the Democratic Republic of the Congo at 5.8 (third and eighth in the world in fertility rates, respectively), and they are now down to where the world’s average fertility rate was in the 1950s. Niger, a much smaller country than Nigeria or the DR Congo, is the lone holdout above 6.
That is still much higher than any rich country of course. Apart from Israel, where the fertility rate is 3 (mainly due to Arab-Israeli and especially Ultra-Orthodox Jewish populations; the secular Israeli Jewish fertility rate is 2.2), no high-income country now has a fertility rate that is above 2.
All this is remarkable, but of course it does not necessarily tell us what the future may hold – certainly not the long-term future. Just as fertility is becoming low now because of how expensive kids are – in time, money, real estate, food, physical exertion, health, and on and on – it could perhaps become higher again if and as humanity becomes richer in all these things. If the future is one of unbelievable abundance, in health and in wealth and in the time to spend both, it could plausibly result in an abundance of children as well, at least in comparison to today’s levels. To put it somewhat simplistically: if we were all mega-millionaires, what would our fertility rate be?
The obvious place to look for clues here is at the current fertility rates of the world’s richest people. But there are a few snags. I was not able to find any estimate for the current fertility rates of millionaires or billionaires. But even if those numbers were easily searchable, they would obviously not be proof of what might happen if everyone in society were that rich. Today’s heirs and heiresses probably feel pressure to emulate their fortune-building parents or grandparents and the rest of society around them. They presumably feel pressure to work hard – in business or in philanthropy – or even just to pursue extravagant leisure, rather than to focus on having a large number of kids. Whereas if almost everyone in society was rich, societal values could perhaps shift to a certain extent away from work or philanthropy, and towards family-building.
At the moment however, no such countries exist. The richest economies in the world today, like Norway or Switzerland or Alberta, are nowhere near being ultra-rich. All of their average incomes are well under 100,000 dollars, and that money is of course not evenly distributed throughout their (small) populations. (Those economies are also poor in winter sunlight or warmth..). Norway and Switzerland both have fertility rates around 1.5, the same as in their big neighbour the European Union. Alberta and Saskatchewan, where after-tax incomes have been very high and housing has been relatively cheap, have fertility rates between 1.5 and 2, which is high for Canada but still below replacement levels.
Still, it may be worth keeping in mind that most parents who have only one child would usually prefer to have at least two, but hold back only because of major constraints having to do with wealth or health. If you were to lift those constraints, it is not hard to imagine that a 2-kid family would become the norm. Even today, among people who are parents in their forties in the United States, nearly twice as many have 2 kids as have only 1 kid. (And 41 percent say they see 3 or more children as ideal, though admittedly that is just a poll). If you buy that premise, the question then would simply be whether or not the number of people having more than 2 kids would be high enough to keep fertility above replacement levels, or if the number of people having 1 kid or no kids would cause it to remain below replacement despite a 2-kid norm.
What is interesting when considering future population growth is that a small difference in fertility rates can make a big difference in the amount of time it takes for a population to (for example) double in size. My math might be way, way off here, but with a sustained, all-else-being-held-equal, long-term hypothetical global average fertility rate of 2.2, the world human population could become something like 18 billion by 2500 and 70 billion by the time Y3K brings down the metaverse on New Year’s Eve, 2999. Whereas a 2.1 fertility rate over that same time could keep the world population around its current 7.9 billion figure. And an average fertility rate of 2 could bring the world population down below one billion (back to mid-19th-century levels) over that same span.
With this in mind (assuming I didn’t completely bungle that math), even acknowledging that fertility rates in the future almost certainly won’t be the same in all places and all times, it seems worth indulging in the thought experiment of what worldwide future fertility rates could be, if the modern pattern between rising incomes and falling fertility ends up fully breaking down.
The Israeli example might perhaps be somewhat instructive here. Not only is the 6.5 fertility rate of Ultra-Orthodox Israelis arguably made viable (as most secular Israelis will tell you) by the fact that the rest of Israeli society is wealthy enough to subsidize it, but even the secular Israeli Jewish fertility is slightly above replacement levels. This might be partly a result of Israel’s economic success, but it might also be partly a result of nationalism, given recent Jewish history and Israel’s sense of embattlement. If Israel today can have a fertility rate of 3, and secular Jewish Israelis 2.2, then we cannot rule out that future countries far richer than Israel, and possibly also as nationalistic or religious as Israel, could have above-replacement fertility rates too.
[Where nationalistic fertility efforts are concerned, it is the Hungarian government that has of late put forward the largest, and the most openly xenophobic, financial incentives to mothers in an attempt to push up its fertility rates. So far these efforts have been fairly unsuccessful – Hungary’s fertility rate is 1.5, and has not changed very much in recent years. But it is early days yet, and there has been a pandemic, and Hungary is not a country that is very rich in money or in land. If a richer country, or perhaps a more autocratic country, tried a similar trick, maybe the results would be different.
What might China do, for example, regarding its low fertility rates? China scrapped its urban one-child policy in 2015 in favour of a two-child policy, and then in 2021 raised that to a three-child policy. A month after that it did away with limits on childbirth altogether. But, as in Hungary, it is not clear that these policy changes have been having much of an effect thus far. Whether or not they or other future policies do work to increase the country’s fertility rate will be significant over the course of the next decade, as the younger of China’s two major population cohorts is currently in its thirties (roughly speaking). They still have at least a few years left in which to have kids.
Considering the even lower fertility rates of its richer neighbours like South Korea and Taiwan, it seems unlikely that China’s fertility is going to bounce back much any time soon. Still, we should not be too surprised if it does end up rising, especially if the Chinese government tries hard to make it do so. China still has a far larger share of its population living in rural areas than other countries in Northeast Asia do. China’s new parents today also very often have no siblings themselves, which means that even if they have two kids instead of just one, most of those kids will have four grandparents to help the new parents with childcare. These (potential) grandparents are also still relatively young. Most are in their fifties or early sixties rather than in their late sixties or seventies.
On the other hand, if the only children who are now contemplating becoming parents in China and other countries worry that they will be left having to financially provide for their own parents as they get older, they may decide to have fewer kids in order to save more money to do so. That China’s fertility will remain low for this reason (and for other related reasons, such as housing costs and long working hours) is perhaps the prevailing narrative about China’s only children and aging population at the moment.
In China, and in India too, it might matter not just how many kids parents have, but also how many girls. In both China and India today there are roughly 11-12 boys born for every 10 girls born. That is the highest gender discrepancy at birth in the world, in the two largest countries in the world! Yet obviously it is girls, not boys, who grow up to bear children themselves. Women also tend to live much longer than men. Even in China and India, despite the early prevalence of boys, there are only about 9 male seniors (65 years and older) for every 10 female seniors. In many countries, there are twice as many elderly women (85 years and older) as men.
Will these gender discrepancies that exist in China and (northern) India change in the years ahead? It seems plausible that they will, whether because of economic development in India, policy shifts in China (during much of the one-child policy era that recently came to an end, for example, rural Han families were allowed to have two kids only if the first child was a girl), or because population aging in China could increase the perceived value of girls, given that it will be daughters and nurses who will tend disproportionately to care for the growing number of elderly people. The government too might decide to work hard towards rebalancing the gender discrepancy, perhaps out of a concern that it will lead to social instability borne of wifelessness.
Relatedly, average lifespans and health in general also matter to the population growth question. Though they have no direct exponential growth impact, as fertility rates do, they can have a linear impact. More old people can mean more people alive at one time. Perhaps more importantly, they could indirectly influence fertility rates. If you expect to live a long, relatively healthy life, you might become likelier to have more kids than you otherwise would.
True, this has not happened in countries like Japan or South Korea, which have among the highest average lifespans in the world, but low fertility rates. But Japan and South Korea are also extremely urbanized and densely populated, their populations tend to work long hours, and they are not close to being among the very highest income countries, in nominal or purchasing power-adjusted terms. Nor, perhaps, are their lifespans yet as long or as healthy as they will become in the future.
Today, the average lifespan in China, India, and Africa is 77, 70, and 64, respectively, whereas many high and medium-income countries have average lifespans of 80. (Japan is #1 at 84.3, the US is #40 at 78.4). If the world average lifespan were to rise from 72.7 today to (if we’re very lucky) 90, which is the current average lifespan of women in Japan, that could lead to a significant increase in the world’s population over time, if fertility rates do not continue falling]
But back to the main point. This speculative theory, that sustained economic growth could plausibly lead to sustained fertility rates above replacement levels, and so to massive population growth over an extended period of time, despite current trends which have generally seen rising incomes lead to a rapid fall towards replacement levels, begs in turn the dismal question of Malthus: will population growth eventually outpace our ability to provide ourselves with basic necessities?
This used to be worried about a lot a few decades ago, but thanks to crashing fertility rates and the green revolution it is no longer much discussed today, except of course in the context of the very worst climate change scenarios. When Malthus is invoked now, it is usually limited to the regional issue of Sub-Saharan Africa, or else to local or national concerns that religious groups will grow rapidly in population over time while secular majorities dwindle by comparison. (This worry about minority populations growing rapidly may usually be a right-wing fear of immigrant groups, but there are left-wing versions too. For example, the fear that some secular Israelis have about the rapid population growth of the Ultra-Orthodox Jewish Israeli population).
Sub-Saharan Africa’s still-rapid population growth hopefully will continue slowing down. Doing so would benefit Africa in particular but also the world at large, which probably does not need the entire 1-1.5 billion in additional population that Africa is currently expected to provide between 2020 and 2050.
As for the worry that the most extreme religious groups will keep up their extremely high fertility rates – sorry to bring up Ultra-Orthodox Israelis again, but their fertility rates are higher than even any country in Sub-Saharan Africa – I don’t know how likely it is that these high fertility rates will actually manage to be sustained over the course of the coming generations. It would take a number of generations of extrapolating current demographic trends for a religious population like the Ultra-Orthodox to become a majority of the population in a country like Israel, and before that happens it is perhaps more likely that economic developments will help make ultra-religious people have lower fertility rates than they do today.
Fertility rates among the most religious groups could fall because of increased exposure to secular society, or because of economic scarcity within the rapidly growing ultra-religious population. (Not for nothing was Malthus a clergyman). This scarcity could exist in absolute terms because of population growth within the religious group, but also in relative terms, when compared to increasingly wealthy secular societies.
Invoking the Israeli example one final time, one can see that all of this has probably already been happening in recent years. Religious fertility rates have been falling, the amount of exposure to secular society within religious society has been rising, and economic scarcity within religious society has in many cases been rising both in absolute terms and relative to the increasingly wealthy secular or traditionally religious (rather than ultra-religious) populations.
Perhaps the extreme scenarios that are likelier to occur in the future are ones that take place on the smaller scale of the religious cult, rather than the larger scale of an entire religious movement. A cult, whether of the new-age or old-school variety, could decide to try to use the (hypothetical) wealth and technology of the future to try and have as many children as possible, for as many generations as possible.
I don’t know how likely this actually is, but if a new fertility cult of, say, 1000 couples each had ten children over the course of three generations, it would grow to more than 120,000 members (assuming nobody were to leave the group or die during this time, and that new spouses could be brought into the group in each generation). Add an unlikely fourth generation into the mix and those 1000 original couples would have grown themselves a city-sized cult, with over a million members, to preside over in their elderhood.
Crazier still, it is not impossible that a cult could select for gender so as to have all female children, or almost all female children, and then grow the cult at an even more rapid clip through polygamy, or sperm donation, or (less rapidly, but still very creepy) by attracting men to join up in each successive generation.
Again, I don’t think anything like these scenarios are likely either (although I would have also found unlikely many of the 19th and 20th century cults or new religions that really did come to pass). But there is a scenario that I do think might happen, particularly if average lifespans and incomes both increase. It is one in which there is a massively growing disparity between the number of descendants that different individuals have over the course of their lifetimes.
People who have lots of kids, and then even more grandkids, and then even more great-grandkids, and perhaps even great-great grandkids too, could become sort of like the patriarchs and matriarchs of old, only with (perhaps) no polygamy. A couple who has, say, 5 children, and then the 5 children average 2 children of their own, and then the grandchildren all average 2 children as well, could end up as an old man and wife in a clan with over 70 members (and lots of pet dogs). And this is not counting the dozens or even hundreds of great-great-grandchildren who they might live to see if they started having their children at a young age, or if they live to a very old age. Meanwhile, people who have no kids, or just one kid, may be likelier to be part of the same small types of families that have become the norm in recent years and decades.
As usually happens when trying to speculate wildly about the far future, even despite the optimistic premise that abundant wealth and health is attainable, this is starting to sound less and less utopian…