The New Population Bomb

Is declining fertility demographic suicide or postmodern preference?

Worth the trouble?

On April 22, 1970, my girlfriend and I took over our high school for the day. We had convinced the principal to let us conduct a “teach-in” on two of the world’s most pressing problems: pollution and overpopulation. Teachers cancelled classes and set up microphones so that two thousand teenagers could gather outdoors to hear how we were poisoning our planet and breeding so fast that we would soon run out of food and starve.

This was Earth’s first Earth Day and it was a big deal.¹ An estimated ten percent of the US population, Republicans and Democrats alike, turned out to advocate for stronger environmental protection. Governors and senators jumped on board. New York City Mayor John Lindsay closed Fifth Avenue, which was soon jammed full. It helped that the previous year, a tanker had spilled three million gallons of crude off of Santa Barbara and that Cleveland’s polluted Cuyahoga River caught fire. It also helped that a Stanford professor named Paul Ehrlich and his uncredited wife Anne published an apocalyptic manifesto called The Population Bomb.

The Ehrlichs pulled no punches: “The battle to feed all of humanity is over,” they wrote. “In the 1970s the world will undergo famines—hundreds of millions of people are going to starve to death.” Ehrlich spread this message everywhere. He was on Johnny Carson’s Tonight Show more than twenty times. Since he wrote these words, however, global population has more than doubled, and real income per person has tripled.

Earth Day made environmentalism a permanent force in American politics. Within months, Congress passed the Clean Air Act and Nixon created the Environmental Protection Agency. We got the Clean Water Act in 1972 and the Endangered Species Act in 1973. In response to Ehrlich-inspired fears of famine and environmental collapse, India and China intensified their family planning programs. They subjected millions of women to forced sterilization, mandatory IUDs, and unwanted abortions. The US government increased funding for organizations like Planned Parenthood and the United Nations Population Fund.

The Left was Half-Right

With a half-century’s hindsight, seventies environmentalists were right about pollution but wrong about overpopulation. The population bomb was a dud. Instead of mass starvation, most countries struggle with obesity. And astonishingly, global population is now imploding.

Lower birth rates are not a simple matter of couples wanting fewer kids. We now have fewer couples, in part because many men have not adapted to women's growing professional, economic, and cultural aspirations. Rejected men are helping to fuel the rise of far-right political parties. Let’s take a closer look.

McKinsey Global Institute (MGI) reports that two-thirds of humanity lives in countries with fertility below the replacement rate of 2.1 children per family. The UN, which predicted that the global population would exceed twelve billion as recently as 1992, now expects the population to peak at 10.3 billion in 2028. Private research published in the Lancet predicts 9.7 billion in 2064.

This is an enormous change. For centuries people reproduced as fast as we could, but lost most of our babies before they reached age five. Not until 1805 did humans manage to create a global population of one billion people. We hit two billion in 1927, the year my dad was born. By the time I graduated college, we had doubled again to four billion. Today, we have doubled to over eight billion – but in 2023, for the first time in our species' history, we may have slipped below global replacement fertility.

To picture the difference fertility rates make, consider how many grandchildren descend from a group of 100 people. If each woman has seven children, a rate that occurred in sub-Saharan Africa during the 1950s, one hundred people will produce 1,225 grandchildren. The population is stable at two children per couple, so one hundred people produce one hundred grandchildren. At South Korea’s rate of .7 children per woman, one hundred people produce twelve grandchildren. At a .7 fertility rate, most young people live alone, siblings and cousins are rare, and lots of rural buildings are empty.²

Fertility has fallen so fast that some countries are already shrinking. Europe's population is now declining. China just announced that its population fell for the third year in 2024. Japan’s population has fallen for 15 years, while South Korea began shrinking in 2021.³ Italians had fewer than 400,000 babies last year for the first time since the 19th century, leading Prime Minister Giorgia Meloni to announce that her country is “destined to disappear.”

Low fertility rates have become political. It fuels MAGA’s “childless cat lady” memes. Many Trump fans see declining fertility as a greater threat than climate change and part of a liberal plot to increase immigration. Perhaps because a reduced population undermines the logic of colonizing Mars, Elon Musk has declared it “the biggest danger civilization faces by far”. (Credit Musk for his heroic personal effort to buck the trend by fathering thirteen children by four women.)

Because conservatives have more kids than liberals do, Americans are now divided between those with families and those without. Counties that voted for Trump had much higher fertility rates than those that did not. Moreover, partisanship now partially predicts fertility. In 2012, vote share explained just 8% of the variance in fertility between counties, but that number grew to 26% by 2024. In other words, political partisanship accounts for over a quarter of the variance in county fertility rates.

Analyzing states instead of counties yields similar results. If you take the ten states with the highest and lowest fertility rates, it is apparent that people who live in Republican states are having more children.⁴

Until recently, liberals have been reluctant to grapple with the political and economic implications of a declining population. Some (including the Economist) incorrectly attribute the decline to falling teen pregnancies. Many dismiss concerns about declining fertility as coded attacks on reproductive rights. Others shrug and imagine that having fewer people would somehow improve sustainability. Democrats should contemplate the likely impact on the Electoral College of power shifting to states with higher fertility rates (and lower housing costs, which attract young families).

Environmentalists are mostly but not entirely wrong to celebrate population declines. Fewer people may reduce specific environmental pressures, such as those produced by airplanes or coal-fired power plants. It can reduce deforestation and slow the extinction of some species. It might diminish pressure on housing, infrastructure, and services we have restricted ourselves from building.

However, on balance, the costs of having fewer people vastly exceed the benefits. When generations shrink in size, the population pyramid becomes an obelisk. It means that each young person must support more old folks who need medical care and Social Security. As Japan discovered, an older population means less creativity and cultural energy and slower levels of innovation and productivity growth. Countries with younger populations (primarily African) will gain economic and military influence over older countries. As extended families disappear, towns, schools, sports teams, and social support all decline. This is not a formula for global prosperity.

Modern nations increasingly confront a dilemma: they need an expanding working-age population to sustain a social safety net. As fertility drops, the need for immigrants increases. However, immigration is incredibly unpopular in slow-growing economies, so economic growth suffers.

We are in uncharted waters, but the demographic arithmetic outlined by MGI is grim. At current birth rates, developed economies cannot support existing income and retirement norms. McKinsey (MGI) figures that developed countries must either double their productivity growth or ask younger people to inherit lower growth, higher retiree costs, and less wealth. Countries that cannot raise fertility rates to avert depopulation will confront a social shift without precedent in modern history. Perhaps in a nod to Ehrlich one think tank calls the shift “demographic suicide”.

Pay for Babies or Pay for Marriage?

Dozens of countries have tried to increase fertility rates by paying couples to have babies. They have poured billions of dollars into cash incentives, tax breaks, and subsidized child care. Nothing has worked. Child care is basically free in Austria and very expensive in Switzerland, but fertility rates are the same and falling in both countries. China offers free fertility treatments. Hungary tried significant tax exemptions and cash. Singapore gives cash grants to parents and grandparents. The Japanese government even funds AI-powered matchmaking apps. One Danish company ran a catchy ad campaign urging couples to “Do it for Denmark”. That didn’t work.

Baby bonuses are trying to solve yesterday’s problem. In recent years, birth rates have declined less because couples do not want children and more because young people have not formed couples. The sharp rise in singles has driven fertility rates lower.

This is new. With the invention of birth control pills, American women cut the size of their families from four kids to two between 1960 and 1980. The share of women in couples declined only slightly during this time. During this century, however, declining fertility is less a reduction in childbearing and more a sharp rise in singledom. Relationships are becoming less common and less durable. In 1980, six percent of 40-year-olds had never married. By 2021, it was 25 percent, including 22 percent of women and 28 percent of men. The decline in fertility in the United States since 2005, for example, is due entirely to lower marriage and cohabitation rates, not fewer kids per couple.

Obviously, many people are happy being single. Everyone needs to choose who to spend their life with—or without. But those with the lowest incomes and the fewest choices are experiencing the steepest rise in singledom. This is not just true in developed countries. The Financial Times documents a global “relationship recession.”

The growth of singledom means that even when public policy manages to nudge birth rates higher, they are pushing uphill. For this reason, China has concluded that they need to promote marriage, not simply babies. Their latest idea? Employers are threatening to fire single workers who don’t get married. This family policy looks to work just as well for China as did forced sterilizations, mandatory abortions, or its infamous “one-child policy”.

Thank U, Next

When culture shifts everywhere at once, something has changed across borders. What could this exogenous shock be? Growing evidence points to the impact of increased internet access and women’s educational attainment. Mobile internet access affects men and women differently. The Financial Times:

“Geographical differences in the rise of singledom broadly track mobile internet usage, particularly among women, whose calculus in weighing up potential partners is changing. This is consistent with research showing social media facilitates the spread of liberal values (notably only among women) and boosts female empowerment.

“The fall in coupling is deepest in extremely-online Europe, east Asia, and Latin America, followed by the Middle East and then Africa. Singledom remains rare in South Asia, where women’s web access is more limited.”

Education and internet access appear to change women’s expectations of their partners. More highly educated women adopt more liberal ideas, but men do not. Educated women often prefer partners with similar or higher levels of education, liberal views, and financial stability. This creates a “mismatch” problem, where educated women find a shrinking pool of suitable partners and less educated men find their attractiveness as long-term partners reduced. Or, as Ariana Grande memorably put it: “Thank U, Next.”

In a recent interview, Alice Evans, social scientist and author of The Great Gender Divergence Substack, noted that education differences are important, but cannot fully explain the relationship recession.

“…even in countries where female employment rates were very low, like much of North Africa, the Middle East and in South Korea — which has got the largest gender pay gaps in the world of over 30 per cent — we still see this massive plummeting of relationships. So it’s almost as if women are saying, even if I need to subsist on my smaller income or live with my parents, I’d rather do that because my values and aspirations are slightly different than my mother's.

“So what I suggest is going on is this term, which I call “cultural leapfrogging”. So right across the world we see this massive growth in access to the internet and smartphones. Now once a woman has her own phone, she can, you know, dial in to whatever. And she enjoys this, this plethora of this amazing breadth of entertainment and media and stories, online literature. So women increasingly tell their own stories in Chinese literature, and they get different ideas and their aspirations for relationships change. So in China and South Korea, women don’t necessarily want the same lives as their mothers. So, you know, in South Korea, a massive hit was Born 1982, which is all about everyday sexism. So young women are increasingly rejecting that.”

The relationship recession is not politically neutral. Those concerned with the rise of authoritarian political parties are beginning to realize that a substantial number of low-paid, low-status men are not only economically imperiled, they also feel unwanted, unvalued, and frustrated because women do not pay attention to them. It is one thing to have a world of increasing singles. This isn’t necessarily better or worse than one centered on couples and families. But a world with many frustrated, low-status young men brings real social, economic, and political dangers.

One of the first people to realize the political potential of frustrated young men was MAGA guru Steve Bannon. As I described earlier in Bachelors Without Bachelors, in the process of advising a friend with a gaming business, Bannon discovered millions of intense, frustrated, predominantly incel young men. He concluded that “these rootless, white males had monster power.” Bannon co-founded Breitbart Media, targeted disaffected young men, and mobilized them for Donald Trump's 2015 presidential campaign.

Some countries, including the United States, Canada, and Australia, have relied on immigration to offset the decline in births to native-born residents. This has generated an intense cultural and political backlash in much of Europe and the US. A country that relies on immigration to stabilize its population often finds that assimilation and cultural integration can be major challenges. Even in countries like the US that are good at assimilating immigrants, discover that immigration is a stop-gap measure because birth rates are dropping everywhere. African fertility rates are well above replacement levels today, but are falling fast.

Population decline is a slow-moving crisis with severe economic and social consequences. Pro-natalist governments have tested economic incentives to increase birth rates, but none have reversed the trend. The challenge isn’t just money—it’s profound cultural and economic shifts that aren’t easily undone. Is the population bust demographic suicide or postmodern preference? It may be both.

Musical Coda

1. Credit Walter Reuther and the United Autoworkers for financing the considerable costs of organizing the first Earth Day in 1970, as he had done for the 1963 March on Washington, which gave us King’s "I Have a Dream” speech. Tragically, Reuther died in a plane crash three weeks after Earth Day.

2. This example uses simple, unadjusted fertility. Total fertility recognizes that not all children live long enough to reproduce. Demographers typically calculate the replacement total fertility rate at 2.1 children per woman to account for these premature deaths.

3. South Korea’s fertility rate is the lowest in the world. It is prominently featured in Gideon Lewis-Kraus’s terrific essay “The End of Children” on life in Korea. Last week, the Korean fertility rate made headlines worldwide because it ticked up slightly in 2024 from .072 to 0.75 – still the lowest ever recorded.

4. Insert the usual caveat here about not confusing correlation with causality. We cannot say whether becoming conservative causes higher fertility rates, or having babies makes people more conservative. Causality may flow both ways – or hidden variables like differences in education levels and lower red state housing costs may confound attempts to establish causality. Also, higher Republican fertility does not confer conservatism with a long-term “demographic destiny.” As Democrats discovered in 2024, children grow up to adopt political beliefs that correlate only moderately with their parents’ views.