Humanity may be scrolling its way out of existence.

Across the globe, fertility rates are plummeting. In 2023, the average number of births per woman worldwide fell beneath 2.1 — the minimum level necessary for averting population decline (also known as the “replacement rate”). And this collapse is not concentrated in just a handful of places; more than two-thirds of all nations now have below-replacement fertility.

While this crisis has been building for decades, its nature recently changed. In the 20th century, fertility fell primarily because couples started having fewer children. Now, it is falling mostly because fewer people are forming couples — or having sex at all.

If these trends continue, the consequences will be transformative — and possibly, catastrophic, as graying populations place unprecedented burdens on the remaining young. Vast countries will swiftly shrivel into city states. Today, Thailand is home to 63 million people. In two centuries, that will fall to 2 million, if the country’s current fertility rate persists.

These are just 23rd-century problems. If sustained indefinitely, today’s global fertility rate would ensure humanity’s extinction.

And it’s partly your phone’s fault.

Or so one leading theory goes. To make sense of recent fertility trends, some analysts have turned to the devices in their pockets. In the view of the journalist John Burn-Murdoch and social scientist Alice Evans, the smartphone helped birth the global spike in singledom.

Their argument goes (partly) like this: As smartphone ownership skyrocketed globally during the 2010s, more and more young people tapped into a vast, omnipresent trove of personalized entertainment, which reduced their incentives to socialize in person. When you have virtually every movie, TV show, and pornography ever made at your fingertips, you no longer need parties for stimulation or diversion. And when you have an X or Facebook account, you can participate in a public conversation — and experience communal recognition — without ever leaving the comfort of your goon cave.

Yet this withdrawal from in-person socializing reduces young people’s opportunities to meet romantic partners or develop social skills. Relationship formation falls as a result.

“The digital revolution has played a signal role in both degrading socialization for young adults and dividing young adults from one another,” Brad Wilcox, a senior fellow at the Institute for Family Studies, told me.

And that revolution is only just beginning. After all, the tech sector’s quest to make social isolation more appealing did not end with the advent of the iPhone, Netflix, or TikTok.

Since 2022, more than 1 billion people have gained access to an infinitely patient conversation partner — one who can speak knowledgeably about all of their interests and listen compassionately to all of their problems. Thanks to Claude and ChatGPT, hermits can not only enjoy perpetual stimulation without social contact but also forms of emotional support that had previously required an intimate friend, family member, lover, or licensed therapist.

And these are the worst versions of these products we’ll ever see. Future iterations may take even more engaging forms; someday, Claude might be able to get it on.

This makes the “smartphone theory” one of the more important hypotheses of our time. If its narrative is correct — and there is some compelling evidence in its favor — then the fertility crisis is liable to deepen in the coming years. And AI might be replacing more than just our jobs.

Before digging into the “smartphone theory” of falling birth rates, it’s worth clarifying its scope.

No one thinks that digital technology is the primary cause of declining fertility, a trend that predates the iPhone by more than a century in wealthy countries (Swedish farmers did not start having fewer kids in the 1880s because of TikTok).

Rather, the main drivers of the long-term fertility descent appear to be foundational features of modernity: When scientific systems of healthcare and sanitation reduce child mortality, couples feel less compelled to have six kids in the hopes that three might survive. When industrial progress boosts the returns to education, parents have an incentive to invest more resources in each individual child’s development, making large families harder to sustain. And when women secure political rights, economic autonomy, and reliable contraception, fewer choose to spend decades of their lives perpetually pregnant.

Yet these structural forces only get us so far. Modern medicine, economic development, and women’s emancipation may have put humanity on the path to collapsing fertility. But some other factor recently sped us on our way: In the aughts, fertility rates actually plateaued globally and rose in advanced economies — before abruptly plummeting in the 2010s.

During that same decade, rates of singledom also spiked. In countries as varied as the United States, South Korea, Turkey, Tunisia, and Finland, young adults became less likely to have a romantic partner. And this “relationship recession” seems to have fueled the post-2010 drop in fertility. According to a 2025 study published in Nature, mothers in most high-income countries are having about as many children as they did decades ago. Yet fertility rates are falling nonetheless, due to a steep drop in the share of women who have any children at all.

The coupling collapse can’t be explained by a sudden expansion of women’s rights; it is happening even in deeply patriarchal societies like Saudi Arabia. Nor is it easily attributed to economic turmoil; rates of romantic partnership have fallen in both high-growth and low-growth nations, advanced economies and developing ones, countries rattled by the 2008 crisis and those largely unharmed by it.

Smartphones, on the other hand, were in the right places at the right times.

In country after country, the rise in singles — and drop in birth rates — coincided with the mass adoption of smartphones, according to an analysis from Burn-Murdoch, the journalist at the Financial Times.

Correlation isn’t causation. But there’s reason to think this timing isn’t coincidental.

In one recent study, economists from the University of Cincinnati examined how teen fertility changed in different American and British localities as they gained access to 4G mobile networks. They found that the arrival of high-speed internet consistently accelerated declines in adolescent birth rates and conceptions. Their explanation for this phenomenon is straightforward: When the center of adolescent life moves online, in-personal socializing declines — and with it, opportunities for one thing to lead to another.

Time-use data lends credence to this theory. Across 21 European nations, the share of people who got together with their friends on a daily basis fell from 21 percent in 2006 to 12 percent in 2022. In the US, meanwhile, time spent on in-person social interaction has plunged during the smartphone era.

Taken together, these data points appear to tell a simple story: When humans acquire 24/7 access to social media platforms and unlimited digital entertainment, they feel less need to hang out with peers in the real world — and demand more from potential partners.

“When phones become ever more engaging and ever more exciting, then you want a super engaging person,” Evans, the social scientist, said. “He’s got to be better than an episode of Bridgerton.”

Thus, some retreat from the frictions of in-person socialization entirely. Others forfeit opportunities to hone their social skills or find suitable but imperfect mates. Sexlessness ensues.

It isn’t hard to see how AI could accelerate these trends.

Streaming and social media might have made the solitary life less dull and uncomfortable. But Pornhub won’t talk with you about your career anxieties, favorite Civil War battle, or debilitating fear of iguanas. And TikTok won’t provide discrete reassurance about that new mole on your chest. Before 2022, securing this sort of sympathetic ear typically required forging and sustaining real-world relationships.

But now, Claude, Gemini, and ChatGPT are happy to oblige.

Thus, if smartphones were outcompeting offline interaction before they hosted chatbots, they seem even better equipped to do so today.

Separately, AI may also widen the gap between young people’s romantic expectations and dating realities.

Frequent interaction with a chatbot — who perpetually centers your concerns, never loses patience, and always has something to say about your topics of interest — could encourage unrealistic standards for human conversation, particularly among those who’ve used AI intensively from an early age.

Of course, these are mere speculations. And research into AI’s impacts on in-person socialization and dating is limited. But there is some evidence that chatbots could be expediting young people’s drift towards solitude and sexlessness.

In a study published in 2025 from OpenAI and MIT, researchers tracked 981 participants’ use of AI chatbots over a four-week period. They found that subjects who voluntarily spent more time talking with LLMs during that span became more socially isolated by the study’s end.

This doesn’t necessarily mean that heavy chatbot use caused people to socialize less with other humans. After all, those who lack hangout opportunities might be more inclined to talk with chatbots. And yet, those who used AI intensively during the study had roughly as active social lives as other participants when the trial period began. Therefore, it seems likely that — at least in some cases — bonding with ChatGPT led to social isolation rather than vice versa.

Meanwhile, survey data suggest that people are turning to chatbots for companionship or romantic stimulation in growing numbers. In a 2025 poll from Brigham Young University’s Wheatley Institute, 19 percent of American adults — including 31 percent of young men — said they had chatted with an AI system meant to simulate a romantic partner.

More recently, the institute examined the use of these pseudo-significant others by young Americans in committed relationships. In its survey, 15 percent of young adults with human partners reported having a secret AI romantic relationship. And among this significant minority, more than 70 percent of men — and nearly 60 percent of women — agreed with the statement, “I wish conversations with my partner were like AI.” And more than half of both male and female users of AI companions said they wished their human partners “behaved like my AI.”

Perhaps more concerningly, respondents who used AI companions regularly were more likely to be in unstable relationships — in which they often thought that their partnership was in trouble, or discussed ending the relationship, or had broken up and gotten back together.

Once again, causality is difficult to determine. People in unstable relationships might be more inclined to seek artificial companionship. But chatbots’ influence on their users’ expectations are likely a factor, according to the report’s co-author Brian Willoughby.

“The more I talk to an AI companion that is always validating me, always taking my side, and always talking about what I want to talk about,” Willoughby said, “the more conversations with my real-life partner — who has their own views — will start paling in comparison to those AI interactions.”

And silicon substitutes for human intimacy will only grow more sophisticated and holistic in the coming decades. Or so many in and around the tech industry believe.

Daniel Faggella, founder of Emerj Artificial Intelligence Research, believes that advances in AI, virtual reality, and mechanized sex toys will eventually render human intercourse an obsolete pastime — one largely confined to nostalgists and connoisseurs, like driving stick shift.

“The great sexual organ is the brain,” Faggella told me. “If you have the visuals, the voice, the haptics, the sound, real-time biofeedback — and even very crude physical implements to go along with them — I think you’re going to beat the human flesh experience every time.”

I suspect that sex has more staying power than Faggella allows. But erotic AI doesn’t need to fully displace intimacy to accelerate the dating recession and fertility crisis. It merely needs to lure a sizable minority of men and women away from the hassle and heartbreak of human relationships. Judging by existing trends, superintelligent sexbots seem liable to meet that challenge.

AI’s effects on human sociality remain uncertain. In theory, artificial intelligence could benefit human relationships and fertility — by, for example, helping awkward adolescents refine their conversational skills or providing troubled couples with on-demand counseling.

Moreover, some experts question how much smartphones actually changed fertility trends. In the view of University of Pennsylvania economist Jesús Fernández-Villaverde, the fundamental causes of the 2010s fertility collapse are long-term structural forces — among them, secularization, the “dissolution of old social networks,” and the rise of a service economy in which women’s relative economic power has increased.

Social media and streaming may have accelerated these processes, in Fernández-Villaverde’s view, by diffusing feminist ideas: Over the past decade, women in patriarchal societies have gained unprecedented access to commentary and dramas that affirm their desire for autonomy and idealize egalitarian marriages (Evans and Burn-Murdoch also put considerable weight on this dynamic). But he believes that this merely hastened already inevitable declines.

“Cellphones matter a little bit,” Fernández-Villaverde said. “But it’s not because people are spending their whole life playing Pokémon. It’s because they’re seeing what the rest of the world looks like and deciding that they want to do things differently.”

Nevertheless, it is clear that mass smartphone adoption coincided with falling in-person socialization — and rising singledom — in all manner of different countries. And there are some signs that AI is further displacing face-to-face interaction and distorting relationship expectations. In any case, the tech industry has a strong incentive to generate evermore compelling substitutes for human connection.

“Here in the Bay Area, all these startups are trying to make apps that will compete in the attention economy,” Evans said. “All these genius software engineers are trying to make something that hooks you in. So I’d predict that the market will enable AI to outcompete humans — they will be funnier, more charming, and enticing.”

At the very least, that possibility warrants concern, given the potential consequences for both fertility and human welfare.

If the past decade is any guide, technological progress may be speeding us toward a future of ubiquitous ghost towns, scarce children, and nursing homes full of gray-haired hermits, each passing their days with VR paramours as civilization slowly unwinds.

There are worse fates. But ideally, humanity would hold out for a better one.