3 Takeaways Podcast Transcript
Lynn Thoman
(https://www.3takeaways.com/)
Ep 257 : Goodbye Baby Boom—Hello Population Bust: How a 60% Drop Could Change Everything
Lynn Thoman: Birth rates have been falling around the world and soon global population will begin to shrink. When it does, will it spontaneously plateau at some smaller stable size or will it fall off a cliff as each generation is smaller than the previous generation? If depopulation happens, what are the consequences?
Hi everyone, I'm Lynn Thoman and this is 3 Takeaways. On 3 Takeaways, I talk with some of the world's best thinkers, business leaders, writers, politicians, newsmakers, and scientists. Each episode ends with three key takeaways to help us understand the world and maybe even ourselves a little better.
Lynn Thoman: Today I'm excited to be with Mike Geruso. Mike is an associate professor at the University of Texas at Austin and is the co-author of the new book, After the Spike. Welcome Michael and thanks so much for joining 3 Takeaways today.
Michael Geruso: Thank you, so glad to be here.
Lynn Thoman: It is my pleasure.
Michael, what do you think is the most likely population future?
Michael Geruso: The status quo future, given the sort of birth rates that we're seeing everywhere in the world today, and not just in the rich countries, but in middle-income countries and low-income countries, is a future where the global population shrinks decade by decade, generation by generation. Sometimes when we talk about slower population growth or peak population, you might get the wrong impression that what we mean is the population will grow, reach some level, and then hang there.
That's not what we mean.
What I mean is that after the peak, the population would decline each generation for as long as people looked around and decided for their lives that the right family size for them was, on average, something that was below two kids.
Lynn Thoman: And the depopulation that you see as our likely future is fairly dramatic. It's a 60 or 75% depopulation, is that right?
Michael Geruso: Yes. Once depopulation begins, once we turn the corner past the peak and start shrinking, that could happen very fast. A global average birth rate of 1.5, which is similar to the U.S. or Europe, would lead to a population that shrinks 10% every decade, which would be two-thirds every century.
So, very fast change, probably at a pace that it's hard to get our minds around, since we're so used to living in this big, populous world. And a growing world is all any of us have ever known or been a part of.
Lynn Thoman: Can you talk a little bit more about the math of exponential decline?
Michael Geruso: I think something important here is that the math of exponential decline is the same as the math of exponential growth. And so, because in the last 100 years, the population has quadrupled, it makes sense that that exponential process, in reverse, could create a decline that was just as fast. Here's an example that I think can give some context.
China's birth rate today is one kid per two adults, one child for each woman. If you think about what that would mean going from one generation to the next, it would mean that, let's say, a generation of 100 adults would have 50 children between them. So, that's two adults, one kid each, on average.
And then, those 50 children would have the next generation of 25 children. So, over the course of two generations, a grandparent to a grandchild's generation, you have a population cohort size that goes from 100 people to 25 people.
China is a pretty extreme example of low birth rates today, but even a population average birth rate of 1.4 like Europe or 1.6 like the United States or 1.8 like Latin America can lead to similarly fast population decline.
Lynn Thoman: There used to be worries, it seems not so long ago, about overpopulation because the global population has increased so dramatically, as you said, from 2 billion to 8 billion. Can you talk about that population spike and what caused it?
Michael Geruso: Surprisingly, the cause of that population spike was not that birth rates went up. It was that death rates went down. So, population growth is the difference between the change in births and the change in deaths each year.
And so, what happened over the last couple [of] hundred years was that we became very good at keeping one another alive, and especially keeping children and infants alive. So, 200 years ago, something between a third and half of all children would have died before age five. And through better nutrition, sanitation, through understanding of the germ theory of disease, through, eventually, vaccinations, we've managed to do a wonderful job of helping kids survive.
And so, that change in survival, where those kids grew up to become adults and have families of their own, that's where the population growth of the last couple centuries came from.
It wasn't from climbing birth rates. And in fact, over this whole time, birth rates have been falling.
Lynn Thoman: What are the countries now that you call the canaries in the coal mine, those whose population is shrinking the most, those with the lowest birth rates?
Michael Geruso: The countries today with some of the lowest birth rates, you've probably heard about. China has a very low birth rate, total fertility rate of one. So, again, that's one kid per two adults.
China has been shrinking in population over the last couple of years. Now, it could be that with migration, a country with a birth rate below two wouldn't shrink. And so, the United States is a country with a birth rate below two.
That's because the migration isn't shrinking in population size. Russia is shrinking, though. Japan has had a low birth rate for a long time.
South Korea has a birth rate of 0.7. That's a situation for 100 people in a grandparent's generation. There'd be something like 15 kids in a grandchildren's generation.
And one of the things that we've learned from these countries that have had low birth rates for a very long time, including European countries, is that nothing yet tried by any government or any movement in these places has managed to bring birth rates back up to the replacement level after they've fallen substantially below it.
Lynn Thoman: So, essentially, you're describing all of the so-called developed countries, the richer countries that have population shrinking. How about India and Africa?
Michael Geruso: India, which was once the center of fears about overpopulation, especially in the late 1960s and 1970s, is today a place with below replacement birth rates, less than two kids for each two adults.
So, it is true that the richer countries have had lower birth rates for longer, but middle-income countries like China now have very low birth rates. Brazil has a birth rate lower than the United States.
Mexico has a birth rate lower than the United States.
So, this is not just a story of what's happening in the richest corners of the world. It's happening in rich countries, middle-income countries, low-income countries.
Lynn Thoman: What about Africa?
Michael Geruso: Sub-Saharan Africa, in particular, is the one region of the world in 2025 where birth rates are still substantially above replacement. Now, birth rates have been falling in Africa. It's just that they have been falling more slowly and not yet to the same low levels as elsewhere in the world.
Most demographers who project out into the future think that African birth rates will continue to fall. So, in 1990, African birth rates would have been close to six children per woman. Today, Sub-Saharan African birth rates are closer to four children per woman.
Many of us expect that birth rates will continue to fall as Africa follows paths towards development and more opportunities and better education that other countries have followed. And so, I think we should expect African birth rates to continue to fall. But today, it is the one high fertility region in the world.
Lynn Thoman: Can you talk more about what's going on with the U.S. in terms of birth rates?
Michael Geruso: The U.S. is interesting. It's actually a bit of an outlier. So, the U.S. has a birth rate of 1.6 in the most recent data, which is from 2024. It's a bit of an outlier in the sense that the U.S. birth rate has stayed higher for longer than in peer countries in Europe, for example. So, for many of the years between 1975 and 2008, the U.S. birth rate was pretty close to two. It wasn't quite two, but it was pretty close there, and it hung there for a long time.
And then since the Great Recession, birth rates in the U.S. and in other places have fallen further.
Lynn Thoman: There are many countries where birth rates have been way below replacement value for many years. You talked about Japan and South Korea and Europe. What kinds of policies have governments tried and how did they work?
Michael Geruso: Let me put aside sort of coercive policies that some governments have tried and focus for a minute on the sort of things that liberal democracies have tried to raise birth rates. That tends to boil down to some version of giving people money. So, sometimes it's literally giving people money in terms of a tax credit or tax break per children.
Sometimes it's giving services in kind, like providing subsidized or entirely socially provided childcare. Sometimes it's been mandates on businesses to fund paid parental leave. So, these are the sorts of things that liberal democracies have tried.
Some of these things move the needle a bit on birth rates. So, making childcare available and affordable seems to boost birth rates a little bit in the research, but none of these things makes a huge difference in birth rates. And, you know, we can see that because we've talked about all of these countries that have had low birth rates for a long time.
They've tried these things. Birth rates remain low in these countries today.
Lynn Thoman: Michael, what do you think is needed to achieve higher birth rates?
Michael Geruso: That turns out to be a pretty difficult question to answer with granularity. And part of the reason for that is that we don't have good examples of programs that have worked to boost fertility to high levels. And we, at some level, are still working to understand what are the causes of low fertility in the first place.
Everyone has their pet theory about why fertility is low, but those theories don't often overlap well. So, you'll hear people say that the reason people aren't having kids is that kids aren't affordable anymore, or that the reason people aren't having kids is that, you know, we've turned our back on the traditions of marriage and religion that would otherwise guide us home to family life, or that the reason that birth rates are low is that people finally have good access to contraception. But none of those explanations fits all or even most of the facts.
And, you know, we could go through those one by one, but they really don't explain things, nor does any other particular explanation.
Lynn Thoman: Let's talk about the timing. When do you think population will dramatically decline, essentially fall off a cliff? And if it's far away, why should we care now?
Michael Geruso: The timeline before the decline starts is a few decades, maybe the 2080s, according to the UN projections, maybe the 2060s, according to other projections that are out there. And once that decline happens, it could be just as swift as the surge in population over the last century. The reason that we should care about this is that, at some level, people are good for one another.
We all get to enjoy better lives today than people did in the past because we live in a time when there's many other people around. The reason that we have pain medicine and shoes on our feet and glasses to correct our vision and gene therapies and parliamentary democracies and all of this advance that we get to enjoy and benefit from today is that we get to live in a time after many other people have lived.
It's the same sun overhead. It's the same dirt underneath our feet. The reason that we get to live better lives today than people 200 years ago is that we know better what to do with these things. All of those pieces of the puzzle of progress came from people, came from other people inventing and refining and passing on knowledge.
Lynn Thoman: Michael, what are the three takeaways you'd like to leave the audience with today?
Michael Geruso: Number one, the world is on a path to global depopulation. That's the status quo future, given the sort of birth rates that are now common in most of the world. So, what feels normal today, families that average out to a birth rate of, say, 1.6, would lead to a profoundly unfamiliar future.
The second takeaway is that people are good for one another. We're lucky to get to live in a world with a lot of other people in it. We're lucky to get to live in a time when many other people have come before us to make the progress that we now enjoy.
Our lives, on average, are better than the lives of people in decades and centuries past. And that's not just because time marched forward. It happened because in recent centuries, there have been a lot of people making that progress.
The third takeaway in putting those first two together is we should hope and work to bend our path away from global depopulation. That's not saying that never-ending population growth would be good. That wouldn't be sustainable.
But endless depopulation isn't sustainable either. It's not something to welcome. We have some time, decades, before we turn the corner and begin shrinking, which means this is important, but it's not a crisis.
And we should be using that time to learn how to better support parenting and caregiving and build a broader recognition of the fact that living in a big world makes life better for each of us.
Lynn Thoman: Michael, this has been great. I really enjoyed your book, After the Spike. Thank you.
Michael Geruso: Thank you.
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This transcript was auto-generated. Please forgive any errors.