In exactly a month, on November 13, 2026, the world will end. Fittingly, our impending apocalypse falls on Friday the 13th.
At least, that was the prediction made by University of Illinois physicist Heinz von Foerster in a highly cited Science paper published in 1960. Though talks of supposed doomsday have renewed in recent months thanks to hyperbolic anxieties over runaway, sentient artificial intelligence, von Foerster had a much different calamity in mind.
For more than a century, the prevailing fear, dating back to English economist Thomas Malthus who lived between 1766 to 1834, was of a booming population outrunning its food supply. Famine would ensue. But Von Foerster broke from that view. He assumed (correctly, as it turns out) that human ingenuity would keep the world mostly fed. The problem, he argued, was that the population would keep accelerating, toward “infinity.”
In a now infamous quote, von Foerster predicted, “Our great—great—grandchildren will not starve to death,” von Foerster and his co-authors wrote. “They will be squeezed to death.” Homo sapiens’ last gasping breath, they predicted, would peter out in the fall of 2026.
It’s pretty clear that von Foerster’s estimate was dead wrong. Not only is the global population (around 8.3 billion people) not expanding near the rate it was when he was writing, but there are actually concerns it’s moving in the opposite direction. In dozens of countries around the world, from South Korea and Japan to much of Western Europe, the concern among demographers has shifted from worries about overpopulation to declining birth rates.
In the United States, President Donald Trump has jumped on the issue, calling himself the “fertilization president” offering tax incentives for new families and even exploring medals for women who give birth to six or more children. Joseph Stalin previously championed that last idea.
So how was a prediction so wrong and still so influential? Human population experts speaking with Popular Science say von Foerster and his contemporaries based their prediction on real trends from the past while utterly failing to see the world changing right before their eyes. Though they may have accurately measured growth rates up to that point, that only tells part of the story.
“He got the picture right just as that picture ceased to be right,” Rockefeller University and Columbia University professor and mathematical biologist Joel Cohen tells Popular Science. Cohen has studied human population changes for years and published the influential 1995 book How Many People Can the Earth Support?
“Von Foerster didn’t know at the time, and in fact, nobody knew” that the all-time population growth had already happened, Cohen adds. “The all-time peak happened in the early 1960s.”
Why did experts think the world would end on Friday the 13th?
Von Foerster and his colleagues published their “Doomsday” paper on November 4, 1960. The dramatic pronouncement hinges on an equation that projects the human population into the future based on past trends.
The team gathered 24 estimates of world population dating back 2,000 years. The key assumption underpinning their logic was that humans differ from other animals because of our unique ability to cooperate and innovate.
Fruit flies in a jar eventually level off as crowding and competition take their toll. Humans, on the other hand, the authors argue, work the other way. The more of us there are, the better we get at cooperating. And the better we get at cooperation, the faster our population grows.
Follow that curve forward, and the population doesn’t just grow; it rockets toward infinity, hitting the so-called mathematical wall on November 13, 2026, give or take five years.
Von Foerster wasn’t alone in sounding the alarm either. Eight years later, biologist Paul R. Ehrlich would publish The Population Bomb, arguably the most influential single text fueling overpopulation fears.
“Both of those guys were right looking backward, but wrong looking forward,” Cohen says.
At a glance, thinking the future will resemble the past seems pretty reasonable. The human population grew steadily but slowly over much of our roughly 300,000 years of humanity. But that changed radically with the onset of globalization, colonization, and the Industrial Revolution.
How fast is the human population growing?
As Darrell Bricker and John Ibbitson note in their 2020 book Empty Planet: The Shock of Global Population Decline, human population passed the one billion mark somewhere around 1800. That doubled to two billion by 1927. Then doubled again just less than 50 years later in 1974. It would then only take another 13 years to cross the five billion mark. And in 2022, we surpassed eight billion.
That remarkable explosion had many causes, Cohen says, but among the most important was the spread of cheap, calorie-dense crops like potatoes and corn from the Americas.
Crucially, though, humans weren’t necessarily having way more kids. They were just far better at keeping them alive.
Human population booms weren’t because people were having more kids
“Humanity got better at keeping the people who were born alive through simple, but important innovations like the germ theory of disease, sanitation, nutrition,” University of Texas Associate professor and economic demographer Dean Spears tells Popular Science.
Demographers like Spears study human populations and how they change over time. He published a book on the topic titled After the Spike, earlier this year. Advances in nutrition and medicine “caused early life mortality rates to fall, so more of the humans who were born survived and that caused the population to grow.”
Factoring in longer life expectancy and reductions in child mortality around the world blows a huge hole in Von Foerster’s calculations. Death rates can only fall so far, and once most children survive, families tend to have fewer of them.
The population boom was a one time explosion, not an ever-accelerating loop.
Overpopulation fears are actually based on a misunderstanding
Von Foerster’s assumption of endlessly accelerating growth, Spears says, was “based on a misunderstanding of where population growth comes from.”
Experts specializing in human population studies at the time actually knew that was the case, Spears notes.
Neither von Foerster’s nor Ehrlich (who wrote The Population Bomb) were human population experts. Von Foerster’s background was in physics and philosophy. Ehrlich was a biologist. But they were both great at getting attention.
Indeed, academics at the time reportedly sent flustered letters to the editor at Science, calling the prediction “ridiculous” and “manifestly absurd.”
“There was never, even at that time, any reason to think that it would keep growing fast like that.” Spears says. “Paul Ehrlich was a biologist who studied butterflies, not human demography.”
Why people are worried about declining birth rates now
In the later 20th century, population growth actually started declining quite rapidly thanks to a convergence of a variety of factors.
The “Green Revolution” in farming meant that more food could be grown on the same plot of land, which extinguished fears of humanity suddenly starving itself. The first birth control pill, approved by the Federal Drug Administration (FDA) in the U.S. in 1957, also gave women more autonomy to decide when and how many children to have.
These trends, along with global population shifts away from rural areas and towards more urban areas, would eventually shift concerns away from overpopulation and towards declining birth rates.
Although demographers and policy experts debate how much people should worry about declining birth rates, it is generally agreed that an older population that significantly outnumbers younger people can lead to long-term strains on the country’s economy and social services.
With fewer workers needed in the field, more and more people moved to cities. Historically, families living on farms or agricultural communities tend to have more children than those in urban areas because those children could work the land and, in a purely economic sense, provide more labor and, hopefully, make the family more money. In more urban areas, another child meant another mouth to feed rather than an extra pair of hands.
In the later part of the 20th century, women in many parts of the world gained far more autonomy through education, work, and access to contraception, which demographers agree is among the biggest drivers of demographic change over the past half century.
Some governments went further. China’s one-child policy (introduced in 1979) and India’s forced sterilization campaigns (between 1975-1977) were heavy-handed responses fuelled by overpopulation panic. What makes those coercive policies all the more tragic, Spears notes, is that birth rates likely would have fallen without them.
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“What we’re seeing now, a world of low and falling birth rates, is actually nothing new, but just the latest moment in a decades-long or longer trajectory of falling global birth rates on average happening essentially everywhere,” Sears says.
“I would say that the coercive [state-sanctioned] school [of thought] was counterproductive,” Cohen adds. He went on to say he believes similar government-led initiatives encouraging families to have more children today, like the Trump administration’s proposed baby medal, are “counterproductive.” Real, meaningful generational changes in population, Cohen notes, are more often the product of society-level macro trends beyond the scope of any one politician or party.
Today, about a month shy of von Foerster’s doomsday, around 55 percent of the world’s countries, home to more than two-thirds of its people, have fertility rates below replacement level. That’s the rate (about 2.1 children per woman) demographers use to denote where a population replaces itself from one generation to the next.
In other words, not only is the human population not hurtling towards infinity, but in much of the world, it’s actually on track to eventually shrink. Experts largely agree birth rates are falling. Whether that’s a problem to be solved is less clear-cut.
At the family level, having fewer children can mean more money, resources, and personal attention invested in each one. It can also mean more independence, opportunity, and choice for those who decided parenthood just isn’t for them.
Stabilizing birth rates isn’t a fix all
At the broader economic or societal level, though, Spears argues there are good reasons to want birth rates to stabilize rather than keep falling. Pay-as-you-go social programs like Social Security depend on young workers to fund older people’s retirements. Fewer people also means fewer shared resources and services for everyone else.
“If you want to go out and eat lunch at a taco truck, but you’re the only person nearby who wants it, then the taco truck’s not going to be there,” Spears says. “And if you’re a school child wanting to go to school, there might not be enough other children for there to be a classroom nearby that’s suitable for you.”
Those are legitimate concerns, though Cohen warns that focusing too much on abstract numbers and trends can blur a more immediate issue directly in front of us. Globally, children are still regularly going underfed, so much so that the World Health Organization estimates around 22 percent of children under the age of five experience stunted growth from malnutrition.
“We are doing so poorly by the children we have that I can’t understand why the emphasis is on making more children,” Cohen says. “We’re talking about having more children when we don’t take care of the children we have. What the heck is that?”
But even for those who do worry about falling birth rates, Spears cautions against politicians promising quick fixes. This isn’t a short-term emergency, he says, but a “generational challenge.” One thing is clear though: Neither Spears nor Cohen are losing sleep over von Foerster’s November 13 death date.
“I’m sure not acting as if I’m too concerned about it,” Cohen says. “I’m still paying my bills. I’m still paying my taxes.”
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