Sometimes, a number is worth a thousand words. One such number is 2.1. It’s called the “replacement rate”: the number of children born to each woman that keeps a population stable without immigration. And in more than two-thirds of the world’s 195 countries, that average number of births has fallen below the replacement rate. In 66 countries, according to a study by John Burn-Murdoch of the Financial Times, the average is now closer to one than two. And in some it is zero.
Combine that with the fact that people are, on average, living longer, and you have the makings of the perfect storm that lies ahead for many societies. Exhibit A in this context is Japan, which currently has about 100,000 citizens aged 100 or more. In 1963 there were just 153 centenarians. The replacement rate in Japan has fallen from four in 1950 to 1.15 now, with consequences that are sometimes, er, awkward. The country now produces more nappies for incontinent adults than for infants, for example. And each solitary Japanese infant born today could have as many as 16 great-great-grandparents vying for his or her attention in due course.
The pyramid of human care will have been turned on its head: from a triangle with a wide base of younger generations at the bottom, with a sharp point of aged people at the top, to an inverted pyramid balancing precariously on a smallish number of working-age people at the very bottom.
This process of inversion has been linked to economic development for a long time. In poor countries, women had many children because infant mortality was high and parents needed someone to look after them in their old age, but as a society became richer, its birthrate declined. In the past 15 years, though, something has changed. Birthrates have steeply declined across different cultures and levels of economic development, and many developing countries now have lower fertility rates than much wealthier ones.
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So what’s going on? First, the data suggests that young people are socialising much less than in the past. In the UK, the percentage of 15- to 29-year-olds who reported socialising at least weekly fell from nearly 90% in 2003 to 70% in 2024. The same pattern is reflected in the US, Europe and South Korea. Second, less socialising means fewer long-term relationships, which means fewer births. “To meet a person you are going to marry requires filtering through a lot of people,” said one demographer. “If you socialise much less, it takes you much longer to find a match – if you find one at all.” Or, as Burn-Murdoch puts it: “In previous decades, the world’s fertility rate went down because couples had fewer children. Now the main reason is that there are fewer couples”.
But the most astonishing thing to emerge from the data is a dramatic correlation between the arrival of the smartphone in a particular territory and the percentage change in the total fertility rate compared with the pre-smartphone era. This holds for Indonesia, Mexico, Senegal, Iran, Egypt, the US, Australia and the UK. In country after country, the birthrate plunged after the introduction of smartphones, no matter what the previous trend had been.
Another intriguing sociological insight comes from Alice Evans of Stanford University, an expert on gender equality, who observes that the more traditional a culture is in terms of its gender roles, the greater is the effect of the smartphone on birthrates. The Middle East and Latin America show many of the steepest birthrate falls of the past decade. “Instagram and TikTok”, Evans observes, “enable young women across the world to bypass traditional authorities... raising their expectation for a relationship in a way their male counterparts are often not prepared for.”
In other words, the overarching drop in birthrates notwithstanding, a positive side-effect is that the arrival of the smartphone has empowered women to become more sceptical about male pretensions – and therefore also more discriminating and choosy. Good for them. And, just for once, two cheers for technology!
What I’ve been reading
God in the machine
The Reality of AI and the Crisis of Meaning is an interesting speech given recently by Matthew Harvey Sanders to a conference of Catholic bishops
Computer says d’oh!
An insightful Substack post by Martha Lane Fox is Homer Simpson May Be the Best AI Commentator We Have Right Now.
Tears in their AIs
Matt Stoller’s The Rage of the Billionaires Is Coming is a combative essay on how the poor tech bros feel misunderstood and underappreciated.
Photograph by Yuichi Yamazaki/AFP/Getty Images