All across the world, people are having fewer children. The birth rate is declining quickly in countries ranging from the United States to Finland to Mexico and Turkey.

Fertility data used to be a fairly esoteric concern. Not anymore. Vice President JD Vance talks about it regularly, Elon Musk calls it civilization’s greatest threat. There’s even a convention for “pronatalists,” Natalcon, taking place later this month in Texas. While worry about the falling birth rate has become a right-wing shibboleth, some Democrats are also leaning into “pro-family” rhetoric.

Why birth rates are declining is hotly debated. Some point to the increase in women’s education and income, others to the cost of childcare and housing. King’s College London social scientist Alice Evans has another theory.

“What has happened everywhere, all at once, is that we see a rise of singles,” Evans told Today, Explained co-host Noel King, “and it precisely correlates with the decline in fertility.”

King talked to Evans for a recent episode of Today, Explained. Click the link below to hear the whole thing The following is a transcript edited for length and clarity.

Give me your name. Tell me what you do and your area of expertise.

My name is Alice Evans and I’m a senior lecturer of international development at King’s College London, and my research focuses on gender…[and the birth rate]. My research has taken me from Mexican villages to the Atlas Mountains to Uzbek towns, through Korean universities. And by talking, learning from young men, older men, and women across the world, I’ve started to think: Why is fertility collapsing? What’s going on? And my interviews have really helped me understand this massive global problem.

So birth rates are going down all across the world. What are the leading theories as to why this is happening?

There’s the right wing, the left wing, and then there’s the Alice Evans take.

Okay!

I think the conservative right in the US will blame childless cat ladies, right? So they’ll say that, yes, women are over-educated, they’re living with their cats and they’re very, very selfish.

Correct.

But here’s the thing: That theory has two........

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