How the Population Crunch Ends

What's next for global birthrates and the secular demographic vampire.

In the 1960s, insect researcher Paul Ehrlich visited India and became convinced humanity was doomed. He was haunted by what he saw as teeming masses living in squalor, reproducing endlessly. In 1968, Ehrlich returned to Stanford and channeled his anxieties into a book called "The Population Bomb.”

The book argued that the human population was rising exponentially, headed for horrific disaster in the form of resource shortages. The idea wasn’t new. Thomas Malthus proposed in 1798 that a given population would rise until constrained by available food. Because increasing populations grow exponentially, Malthus argued, they inevitably outpace food production and only shrink back down through war or famine. This concept became known as the Malthusian Trap.

Malthus’ England had about nine million people. In 1968, Ehrlich’s Earth had over four billion. Ehrlich's predictions involved massive famine, particularly in the Indian subcontinent, which he suggested should be left to starve as a hopeless case. He also somewhat arbitrarily predicted the exhaustion of gold, mercury, tin, zinc, and petroleum supplies by the 2000s.

Ehrlich described a future where governments would take drastic measures to control population growth, including the mass sterilization of the public through water supply. The suffering he warned of was endless, and his proposed solution was clear. He wanted to apply the brakes in immediate, massive ways to slow the growth of the human population.

The book was a huge hit. The idea of overpopulation had already been gaining traction for decades, and this was its peak. The chemical revolution had caused massive advances in agricultural production per square mile, and Earth's population had recently bloomed to a staggering height. Ehrlich, whether deliberately or not, had crafted the perfect tale of doom to capitalize on his moment.

There was a key ingredient to Ehrlich’s instant celebrity. He, a Stanford professor, had painted a picture of a plausible-sounding apocalypse coming in 5-20 years. This is a perfect amount of time for an apocalypticist. It feels imminent, but still gives the author enough time to milk his fame before it becomes clear that his predictions will not come to pass.

The book came to dominate the global conversation on population control. A wave of panic swept the educated world. The most extreme outcome of this discourse was China's one-child policy, which resulted in hardship, heartbreak, and the infanticide of young girls. Western liberal democracies, meanwhile, gritted their teeth and waited for the population storm.

The storm never came. None of what Ehrlich predicted came to pass. The famines and resource shortages all proved immaterial or surmountable with technological advance. The policy decisions he swore would be necessary never manifested. The one-child policy was repealed, and no other country ever took a step toward criminalizing an overabundance of children. In fact, we have massively reduced global poverty since 1968 while at the same time doubling the global population.

Scientists now believe that Ehrlich will get his wish of population reduction without any coercion at all. Sometime in the late 21st century, the United Nations expects, the total human population will settle around ten billion. That's up from eight billion presently. From there, we will begin a slow but increasing decline into an unknown future.

How is this happening? People everywhere started voluntarily having fewer children. This trend began with the most developed countries, then steadily and gradually spread over decades to encompass more and more of Earth's population. It is still spreading, and still growing more acute. A phenomenon of slow growth, then equilibrium, then contraction has taken hold of the world.

Evidence that this would happen was already available when Ehrlich wrote his book. Global birth rates have declined every decade since the 1950s, and this decline shows no sign of slowing down. In 1968, this was possible to overlook. Now it is unavoidable.

You need a birth rate of about 2.1 kids per family for a group to not lose population over time. Two kids replace the two parents, and another 0.1 makes up for various factors like childhood mortality. This is called replacement-level fertility by population scientists. ‘Fertility’ is a bad term for this, because to most people fertility means someone's reproductive potential, not the number of kids they’ve had. Let's keep saying ‘birth rates’ here instead.

American families who make between $30,000 and $500,000 per year are currently far below replacement level birth rates. Those who fall outside that range, the very rich and very poor, are higher, but not by much.

America now has an overall birth rate around 1.65, meaning we will lose 17% of our population each generation. In practice, the American population is still increasing through immigration. Immigration is a clever way to improve a country’s finances, if you do it right. You don't pay for immigrants’ public schooling, and they arrive in your country at a prime age ready to work and pay taxes—the average age of new immigrants to America is 31. You also get to screen for the traits you want in a citizen (by selectively issuing citizenship to desirable applicants).

The issue is, immigrants don't appear from thin air, and they cannot be brought to Earth from other parts of the solar system (yet). If we are assessing birth rates at a global scale, there is no immigration fix. We have to make and raise each new baby if we want to balance the endless stream of dying adults.

The topic of birth rates causes a lot of discomfort for people. Nobody wants to feel judged for having kids, or for not having kids. Reproduction is also the area where the difference between sexes is greatest. From the moment a couple conceives, man and woman embark down very unequal paths, with unequal risk. If you want men and women en masse to have similar burdens and opportunities, reproduction is a tricky complicating factor.

The purpose of this piece is not to compel, disdain, or venerate any individual behavior. I will say it’s my genuine wish to see the human race grow in power over the material universe and lower its risk of extinction. On its face, a permanently declining birth rate seems to be at odds with this.

Luckily, there's little reason to think the situation of declining birth rates will be permanent. It's hard to imagine human beings deliberately withering away from eight billion to zero. Additionally, even with a birth rate of 1.0, it would take a millennium for us to go functionally extinct. A lot happens in a thousand years.

So, when will birth rates stop falling? Will they settle above replacement level? If they fall below replacement level, how long will they stay below, and what will eventually cause them to rise again? How much will world population fall in the process? How painful will it be, if painful at all?

Some go so far as to speculate that immigrants will be an extremely valuable resource in 100 years' time, that countries will be fighting over them out of desperate need. This almost starts to sound like an inverse Ehrlich, a rather doomsday-ish scenario that extrapolates from current trends without considering moderating effects or counterswings. Of course, time will tell.

Another more causal question is: Why is this happening? Why is the population not increasing based on available food, as happens with almost every other animal? Why were Malthus and Ehrlich wrong? A lot of noble animals are reluctant to breed in captivity. Perhaps we have built a form of captivity for ourselves.

Reactionaries like to blame women’s liberation, but birth rates in the United States were already steadily declining by 1800, long before the first wave of feminism. Progressives argue that a social safety net and state childcare, combined with low income inequality, would resolve the crunch. Scandinavia, of course, has all those things to a very high degree, and their birth rates are even more dire than ours.

It's likely we'll never get a perfect answer. The causes are probably numerous, with aggregate push and pull factors in the hundreds or thousands. Poverty, lack of education, and religiosity currently seem to correlate with heightened births, and no liberal government is going to make a policy effort to proliferate these traits.

There are a few countries facing catastrophic low birth rates without an immigration supplement. Japan and South Korea are the most prominent examples, because they are functionally ethnostates and monocultures, which means they are reluctant to solve population issues through the naturalization of foreigners. Thus, their birth rate issues are acute.

In a way, these nations are preview simulations of a future Earth. So long as they keep immigration low, we can watch a sneak peek of our own global future, since Earth itself cannot source extraplanetary immigrants. If they resolve their internal birth rate crises, their solutions may provide a model for the world. If they decide to allow immigration instead, the Earth-simulations will conclude.

There are only a few ways the birth rate decline can end. One possibility is that this trend is anomalous. Perhaps it will quietly, naturally revert to historical norms, making this whole ‘crunch’ line of discussion seem just as silly as Ehrlich's population boom. This is the simplest answer, the most boring, and possibly the likeliest.

Another possibility is that culturally influential intellectuals will become concerned with declining population and successfully convince the masses through reasoned persuasion to change their habits. I don't know how likely that is. However, if you believe that someone like Ehrlich can single-handedly cause population decline through fear-mongering, the opposite must also be possible.

Yet another option is that policy will be enacted at a state level to increase fertility. What this policy would be, I can't say. Nothing that has been tried so far has worked. Cash payments haven't worked. State childcare hasn't worked. If the solution to the crunch is policy, the policy will probably be extreme by contemporary standards. To me, this is the least likely outcome, which is good because it's also the one that seems to scare people the most.

A lot of people fear that pro-natalist policy would come at the expense of women's liberation, accompanied by a hyper-conservative wave. You can look at "The Handmaid's Tale" if you want an illustration of this fear in the American liberal mind. That fictional world, after all, is one where women are enslaved under the pretense of saving humanity from extinction due to a birthright crisis. It's not pleasant.

One thing that can possibly reassure us is the fact that Margaret Atwood wrote "The Handmaid's Tale" about her anxieties watching the Islamic Revolution in Iran, and Iran is not a natalist outlier. Currently, Iran’s birth rate is just 2.1, and that rate continues to fall even under theocratic conservative dictatorship. Bolivia, meanwhile, has an over half female legislature and still maintains a birth rate of 2.7. Top-down repression of women, thankfully, does not seem to be a birth rate panacea.

The last and most interesting potential outcome is socio-evolutionary. Genes are heritable, but so are cultures. Kids, in growing up, become assimilated (imperfectly) into the values of their communities. Ideas, like viruses, spread and reproduce through contact. If we follow this line of thought, the crunch can end when genes and cultures that promote reproduction outbreed genes and cultures that don't.

Let's look at a classic case of inherited culture, religion. In Israel, ultra-Orthodox Haredi Jews have an astonishing birth rate of 6.6, compared to the secular Israeli birth rate of 2.0. At that rate, starting with 100,000 people, you could grow to twelve million in just five generations. It's easy to see how exponential math like that, under crude analysis, gave Ehrlich such alarm.

In the United States, all religious people combined have a birth rate of 2.1, compared to the strikingly low non-religious American birth rate of 1.3. Interestingly, these numbers are very similar to the European statistics of 2.3 for European Muslims and 1.3 for European non-Muslims. When you examine more specific groups, like American Mormons and their birth rate of 2.4, the numbers go even higher.

If a culture tied to high birth rates (such as Haredi orthodoxy) is sufficiently heritable, then its member population is not actually shrinking. The higher the birth rate of the group, the more attrition they can sustain each generation and still maintain population growth.

Imagine the orthodox sect of an arbitrary religion in the nation of Populo. Let's say these orthodox folks have six kids per family on average, but two of those six become secular each generation. The secular kids, in turn, go on to start families with a 1.5 birth rate average.

There's something unintuitive that happens. Even though the orthodox are having four times as many kids per household, the secular and orthodox populations remain effectively neck-and-neck in raw numbers, because ex-orthodox children are continuously ‘feeding’ the secular population. Both grow.

Secular people in our theoretical land don't need immigration or birth rates to maintain growing numbers. They just need a self-sustaining orthodox population to draw from. In a way, this seems almost vampiric. The secular parasite must draw from but not kill the host.

With a high enough secularization rate, host-killing is not hard. If orthodox kids start to convert to secularism at a rate of, say, 5.5 out of 6, disaster strikes.

Changing the secularization rate of orthodox kids to 5.5 out of 6 causes a massive, sudden spike in population, followed by decay as the orthodox wellspring is snuffed out. It's tempting to blame the secular element here for some wrongdoing, but ‘blame’ is irrelevant. A social organism like a religious sect must be fit enough to survive its memetic environment. If Populo orthodoxy is no longer cutting it, they need a more conversion-resistant strain (giga-orthodoxy?) to mutate into existence and begin gaining ground.

This framework, both in its sustainable and unsustainable version, can be applied to more than just religious adherence. If you have any two groups with unequal birth rates and the possibility of ‘conversion,’ a vampire-and-host dynamic can exist.

You can think of it as the rich and poor together having an excess of children, some of whom feed into and become the non-reproducing middle class each generation. You can think of it as rural areas feeding cities, which are continuously replenished by migrants from rural areas, even as urban residents themselves reproduce below sustainable rates. If you have a hyper-reproductive group, a wellspring of high birth rates, this wellspring can create a supply of humans who flow out into other areas and become ‘dead ends.’

We can almost imagine these cities, or the middle class, or secular ideology as machines that consume human capital in exchange for a unique output. This could be highly educated workers, or celebrities, or whatever else we need that requires some strange and childless exceptionalism. People are born to high birth rate families, they leave the nest, they achieve great things for humanity, and in the end don't have enough kids to keep their bloodline going.

This might be worth it. This might even be ideal. The host ideologies just need to be tough enough to last.

So, what do we need to survive, from this perspective? We need better cults, better sects, better natalist fringes. It's fine for them to remain small minorities, so long as they can tolerate vampiric attrition while maintaining their numbers. Perhaps these high-birth fringe ideologies are already in existence, nascent and approaching an explosive critical mass.

In 150 years, the vast majority of people might be descendants of these fringe types. Meanwhile, if the ideologies of today truly lead to near-childlessness, they will shrink unless continuously replenished with new blood. Across a long enough timeframe, one can imagine, the propensity to stay within your fertility cult might become genetically reinforced. It certainly would be selected for.

In my view, it's unlikely that the end of the 21st century will actually be the peak of global population, despite what scientists currently anticipate. After all, they've been wrong before. Whatever the case, these people of tomorrow will be the ones who inherit everything we've built. They will be the ones who tell our story, who remember us, and who set the path for the next chapter. After all, the future belongs to those who are alive to see it.

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