Making the Case for People
Economists Dean Spears and Michael Geruso on falling birth rates, global depopulation, and what comes next
Last month the College of Liberal Arts hosted a discussion about the newly published After the Spike: Population, Progress, and the Case for People with authors and economists Dean Spears and Michael Geruso. In both the book and our hour-long conversation, Spears and Geruso argue that the challenge for humanity’s future isn’t too many people but too few, the inevitable consequence of consistently low birth rates. But where Spears and Geruso go from there differs significantly from the various pro-natalist positions articulated across media today — you won’t find any policy interventions or demands for massive families here, just a call to think harder and deeper about what kind of future we want to build together.
An edited and condensed version of our discussion is below, and more about Spears and Geruso’s work can be found at AfterTheSpike.com.
Mike and Dean, congratulations on the book. Tell us a little about it.
Dean Spears: The big idea at the core of our book is global depopulation. That’s the name for what will happen when, generation after generation after generation, the size of the world population is smaller than the generation before. Depopulation will be the inevitable consequence of low birth rates if birth rates keep falling and stay low.
When I say low birth rates, you might think about the situation in South Korea, where it's an average of 0.7 kids per two adults. But in fact it would be enough for depopulation if the world birth rate were something like the United States' current 1.6 kids per two adults, or even Texas' 1.8 kids per two adults. The critical dividing line is an average of two kids per two adults, so that one generation replaces itself in the next, and if the world as a whole goes and stays below an average of two kids per two adults, then the next generation's going to be smaller and the process will continue.
Our book starts with and goes through those facts and then talks about the myths and misconceptions about population, because population is something that you hear about a lot but that people often get wrong. One way that people get it wrong is that they're stuck in the overpopulation tropes and stories and fearmongering of the 20th century. Or maybe they know that depopulation is coming, but they think that it's something to welcome to solve our environmental challenges — that depopulation will get us off the hook for climate change or it's what we need to decarbonize. But depopulation would be too little, too late for environmental challenges. It isn't going to be the solution for us.
People also often misunderstand why depopulation is a big deal. To understand why depopulation is important, we first have to understand how different it's going to be from what came before. For a long time, the world population was small and not growing very fast. 10,000 years ago, there were 5 million people worldwide — that's about as many as live in Atlanta today. But then something big changed, which is that humanity learned how to keep its children alive. When that happened, the population explosion began. By 1800 there were about a billion of us worldwide, and then our numbers doubled and quadrupled up to today, when there's more than 8 billion people worldwide. That's the world that we know and find familiar. Part of the case for people that we make begins with recognizing that this recent past with a large and growing population has also been the time when living standards have been improving. Global poverty has been receding; lives have been getting healthier and longer and fairer. We think it's not a coincidence that that's been happening in a large and growing world.
The thing to notice now is that all of that is about to change. The size of the world population will soon peak and then begin to decline, not in some distant century but within a few decades, within the life of people alive today. When it does, the pace of the decline could be every bit as fast and exponential as the population increase that brought us here.
The fundamental reason this is happening is because birth rates are falling, and again it comes back to that number of an average of two kids per two adults. The world as a whole right now is at an average of 2.3, and it's not only falling, it's long been falling. It was around five in the 1950s for the world as a whole, around 5.5 in 1900, and people were having an average of six children in the 1800s. So this decline in birth rates is nothing new, and it's projected to continue downwards. Two thirds of people already live in a country where the birth rate is below two. What that all adds up to, for us, is to think that the most likely future is one of global depopulation. We don't know what the future birth rate's going to be, but so many trends going in the same direction suggests to us that no future is more likely than a future of global depopulation and that it's likely enough to be worth talking about and understanding.
Why is this coming to consciousness now? My sense from what you just said and from reading your book is that the long-term trends of declining birth rate have been evident in the statistics for a long time. But it’s also my sense that people have only been talking about this for the last kind of three to five years or so. Why is that? Has something changed, or does it just take a while for people to notice trends like this?
Michael Geruso: I think this fear of overpopulation and this gestalt shift has some important connections to the myths and fears of overpopulation that Dean mentioned from the mid-20th century. While it is true that birth rates have been falling for a very long time — they’ve been falling from the earliest data that is trustworthy that we have — it's been very hard to rectify what that means at a time when the population is still growing. In some sense, the Earth's population is a closed system. The growth rate of population is the birth rate minus the death rate, the number of births minus the number of deaths. What's been happening is we've been getting so good at keeping people alive, improving health and longevity, dealing with both chronic but especially infectious disease, that deaths have been falling faster than births. I think a lot of people have missed the fact that this whole time birth rates have been falling.
Spears: If the question is “why haven't people noticed this before when the trends have been going on for so long?”, I think part of it is that the narrative space was taken up by the story of overpopulation. At some level you can understand why that was a focus, because rapid population growth in the mid-20th century was something new. But another version of your question is, if people back then — let's take the case of Paul Ehrlich, who in 1968 wrote his famous book The Population Bomb —could get it so wrong, then maybe we're getting it wrong too. Why should you have any confidence in what we have to say?
Part of it is that we're not trying to scare anybody, but I think there's a more important research difference. In 1968, there just weren't the research tools that people have available now. We know now about what birth rates were and are doing because more and better research tools are available. There's more information than there used to be. That's at least one place to start.
The elephant in the room with a lot of these conversations is environmental damage and climate change. The strong and understandable intuition many people have is that there's a direct causal relationship between the size of the population and the amount of damage we're doing to the climate. You mentioned this in your intro, Dean, but can you both explain why you don’t think population decline will solve climate change and also explore whether it might not mitigate it?
Geruso: You sort of have to hold two things in your head at the same time. The first one is that human activity causes greenhouse gas emissions and greenhouse gas emissions cause climate change. But I think you asked a really good and subtle version of the question, which is: Does that mean that population decline of the type that we're facing is likely to mitigate those climate damages or relieve us from taking a more active and direct role in dealing with greenhouse gas emissions?
I think this reasoning gets something important wrong. If we think back to other environmental challenges that we faced and where we've succeeded, at least to a large degree, I think there's some lessons there.
Back in the 1960s and 1970s, we had a huge environmental problem in the United States in the form of people breathing in lead in the air, and this was happening because we had lead in our gasoline and it was coming out of our tailpipes. Lead is a terrible neurotoxin — it hurts the cognitive behavioral development of children and it causes cardiac deaths in adults — so this was a huge environmental and health emergency. How did we solve that problem? Through legislation, through the Clean Air Act of 1970 and various amendments to it, and by changing the technology of our automobiles. It would've been silly in 1970 to say, “Okay, we're breathing in a lot of lead. The way that we need to deal with this is to have fewer Americans, or to have fewer Americans driving.” If you want to take the lead out of the air, you have to take the lead out of the air. We can all see why that makes sense, but I think we're making a similar mistake when we say the way we're going to deal with greenhouse gas emissions is by taking the people away, not taking the greenhouse gas emissions away. The way that we need to deal with greenhouse gas emissions, because it is a priority, is to reform our land use and to change our energy systems. We need to find ways to green our industries, to make low carbon concrete and so forth. Fewer people on the planet is not what's going to cause that to happen.
Getting to another part of your question, one easy way to see that that's not what's going to happen is to understand the pace of global depopulation. Dean laid out this timeline that goes back to 1800, where there’s a billion people, to 1925, where there's 2 billion people, to today when there's a little over 8 billion people. We're still on the way up. Global depopulation is coming because birth rates are low, but we're still growing ever more slowly for the next couple of decades. But this decade, the next decade, the decade after that, this is the time when we need to get greenhouse gas emissions under control. This is going to be a time when even though the trajectory we're on is long-term global depopulation, the population will still be rising. So, for better or worse, the population decline does not give us any space to avoid the commitment to actually taking on greenhouse gas emissions.
There are a lot of questions people want to ask about this. Some are about “why is this happening?” And then the others are, “Why, from your perspective, is depopulation bad or worrisome?” Let’s start with the second category. Why do you think this population decline is a bad thing?
Spears: Well, we think something a little bit more subtle than that, which is that in the long run building a path towards a stabilized future population would be better than depopulating generation after generation. Right now the world’s population is projected by the UN to peak in the 2080s and then begin to decline. We think that's probably going to be what happens no matter what conversation we have today. What we're trying to do is start a conversation about whether in the 22nd century it would be better for the population to be moving towards stabilizing rather than depopulating.
There are a lot of parts that go into that case for people. Part of it is that we believe we're made better off by being in a world with other people in it and being in a world where other people have come before us. One question that we like to ask is, “why is life so much better today?” It’s much richer, healthier, longer. It’s fairer. Why? Why is living so much different today than it was 200 or 300 years ago? It's not because the earth is fundamentally providing different raw materials. What's different is that we now know and are able to do things that nobody knew or was able to do a few hundred years ago, and that's because of the people who have come between us and the knowledge, the ideas, and the discoveries that those people have made. It doesn't seem plausible to us that if the population had stayed stable over the past 200 years since 1800, when the world population was 1 billion people, that we would be in the same place with the same knowledge and discoveries. We'd still have the same infections that kids have gotten all along, but we might not have the ability to treat them with antibiotics.
I like to give that example because it shows us that this kind of knowledge and these discoveries are a special type of economic resource. An antibiotic pill is a consumable resource. You give that to a kid, the kid swallows it, it gets used up and no one else is ever going to take that particular pill again. But the formula for the pill, the knowledge in it, the design, that's something that can easily be used again to stamp out more pills. And even better, the idea of the germ theory of disease and the science behind it can be used again and improved upon again. The macroeconomics of where improving living standards comes from tells us that it's from discoveries and knowledge and know-how like that, and that that comes from other people and then gets built upon and used again and again. In the long run, when we're thinking about that far future, that's a reason why a stabilized population would be better than a depopulating world.
It's not the only reason. We also think that the good experiences in good lives count for something good, and that's part of the case for people we make in the book too. But a big one is about continued progress towards that sort of future.
Now let’s go back to “Why is this happening?” What do we know about why birth rates are declining? And more specifically, why are they 1.5 rather than 2.5? I think we have some strong intuitions or knowledge about why they went from 8 to 4 to 3 — birth control, social and economic changes — but less about why they keep going down.
Spears: You've hit on something important, which is that the decline in birth rates from four to three is a larger decline in magnitude than the decline in, say, 2.2 to 1.8. But it’s that second decline that's going to cause population growth to become negative depopulation. What's striking to me about it is that you could cross that threshold without really even noticing it.
That's really the hardest question: What is causing this? Everybody has a theory — that's what social science professors do — but everybody's theory is different. If you want my blunt assessment, I don't think any theory actually captures the whole facts of the case because low birth rates are such a big phenomenon. We see them in so many different societies and we've seen them over such time that I don't think anyone has it exactly right.
You brought up contraception and of course contraception is hugely important, both as a social phenomenon and in people's lives for getting to make the decisions that work for them and for their family. That's essential and an important innovation. The question is, is the global fall in birth rates because of contraception? Some evidence against that is that the fall in many places started before modern contraception. Birth rates have been falling in France since back when France was helping with the US Revolution. And birth rates are continuing to fall now even in societies where contraception has long been available to everyone who wants it. For example, in 2018 the birth rate in Sweden was 1.7 something. Now it's 1.4 something. That continued fall is not because people in Sweden have more access to contraception than they did six years ago.
Geruso: One thing that we talk about in the book is something we hear very frequently from people in our lives and from other social scientists. If the question is “why are we going from 2 to 1.8. to 1.6,” for some people the answer is very obvious. It’s that children are unaffordable, that it's just too difficult and too expensive to be a parent. Our view is that really can't be the explanation, and we think that for a few reasons.
The first is, if you look internationally or historically, it's not been the rich people, the rich places, or the rich times where the birth rate's been high, especially when you're thinking about this transition from 2.5 to 1.9. Sub-Saharan Africa is the poorest region in the world, but it's also the highest fertility region. It's the only region in the world where birth rates are still well above two. And if you look at the history of the United States or even the contemporary United States, it's not that rich people are having huge families and poor people are having small families. It’s pretty flat, and historically it's been that poor families tend to have more babies. So that's one way that you can see that it's not about money.
I know that when people talk about affordability, they're often talking not about incomes but about prices — the price of childcare, the price of healthcare, the price of college. But there are places in the world where childcare is free or heavily subsidized, healthcare is socially provided, and college tuition is free. If you look at those places — Sweden, Denmark, Finland — those are not places with higher birth rates than the United States. They're places with lower birth rates than the United States. Obviously there's a lot that determines such a big thing as a society-level birth rate, but it's certainly not the case that in places where it is just cheaper in some sense to raise a child, where it's more attainable financially, that that's what people are choosing.
What might we deduce from looking at these countries or communities that have higher birth rates? I'm thinking about very religious communities, like the Amish or ultra-orthodox Jews. I know their rates have been declining as well, but they’re still much higher relative to the median birth rate of developed countries and even lesser developed countries. Am I right in my sense of where the higher birth rates are? And if so, is there any conclusion we can draw about what that says about why they might be declining elsewhere, like secularization and cultural shift and modernization?
Spears: We hear a lot about, “what about the Amish?” But I want to push back a little bit on the relationship between religiosity and birth rate decline, at least at the biggest picture. In Latin America, for example, a 2014 Pew survey found that 90% of people there identified as Christian and 70% are Catholic. 2014 was also the year in which Latin America crossed the replacement level, and Latin America is at 1.8 now. I study India where there's long been this really unfortunate conversation, especially from Hindu politicians, saying that Muslim birth rates are too high. But if you look at demographic survey after demographic survey in India, yes the average Muslim birth rate is higher than the average Hindu birth rate, and of course there could be reasons for that about social inequality, but you see them falling over time such that the average Muslim birth rate now in India is lower than the average Hindu birth rate was when this whole divisive conversation started.
So, I think part of what we believe about all of this is a little bit of cherry picking. We know about the Amish, but we don't include in our narratives the Catholics of Quebec who had birth rates in the mid 20th century that were second to none — six, eight, nine kids on average not that long ago because of a culture that was important to people there — but their birth rates have fallen more in line with other people in their population. In other words, we don't include in our mental models the places that don't fit the story, and then we think the story is more important.
What's going to happen next? Are the Amish going to overpopulate the entire world? We talk about this a lot in the book, but the answer is no. If you're a parent, you probably understand that your kids aren't going to grow up and do everything that you think they're going to do, and that turns out to be an important part of the answer.
We have a question from the chat about gender. Susan F says, “I have a couple of questions about gender and about women, because to me it's such a huge component of this. I appreciate if there's an effort to keep the conversation gender neutral, but I'd love to know how the decline in population aligns with the incremental increases we've had over the years in the permissibility of women engaging outside the home. And if the decline should be reversed, how could it be reversed without taking away that permissibility? Are there solutions?”
Spears: Let me talk about both sides of that. One is that the evidence for the correlations contain some surprises. It might not be what you think.
Here in a place like the United States, we're very familiar with the idea that low birth rates could be part of a conflict between career and family. In fact that's the title of Claudia Goldin's book, Career and Family. She won the Nobel Prize for her work on gender, talking about just how hard it is to fit everything in and how that creates gender inequality. I couldn't emphasize the importance of that story enough, and yet when we look at a place like India, which is now below replacement, that's a place where female labor force participation is 40% and many women don't work outside the home. So it’s not only happening because of this conflict you’re describing. India is an example where we're not seeing the same loosening of traditional gender norms, we're not seeing as many women working outside the home, and we're still seeing low birth rates, which tells us that there's additional headwinds.
Another surprising fact in that when you look amongst rich countries and compare their gender wage gap, or how much women are paid on average relative to men, and their birth rates, there's not a lot of relationship until you include South Korea in your data. South Korea has the most unequal gender wage gap and also has the lowest birth rate. That again suggests that it's not a simple story of liberalization that's causing it. There, in fact, the social scientific understanding is that maybe it's just the opposite. Why would a woman choose to be a parent in a situation where she knows that that's going to put her in an unequal and disadvantaged situation?
But I want to also get to your other question, because it's really important to us and why we wrote this book. Part of what our book's doing is making the case that eventually and in the long run stabilizing the population at some level would be better than depopulation generation after generation. It's very reasonable to ask, “What does that mean for continued progress towards gender equity and what does that mean for women?” After all, every person starts in a pregnancy, which starts in somebody's body, so you might think that stabilizing the population rather than depopulation would have to mean regressing to worse gender norms and giving up on the fight for equity. We don't think so. And the reason that we don't think so is because, when we just say “stabilize the population,” we haven't said anything about how to stabilize the population. What sort of path society might someday find is an open question. The only path that we would endorse and advocate for is one that's rooted in not only freedom and choice and access to contraception and abortion but that comes through making parenting better for parents who choose to parent. In the long run, if we want a stabilized future, it's going to be because we've all come together to lift and share the burdens of care work and make parenting better for people who choose to do it.
Let's imagine China, which for many years had this very coercive one child policy because they were worried about overpopulation. Let's say, and this is not unimaginable at all, that China flipped and decided to deploy the coercive mechanisms of state control to try and increase their population. Do we even know what they would or could do?
Spears: There's the example of Romania. Under Ceaușescu in the 1960s, Romania's Decree 770 used the coercive power of the state to, for example, force women to go to pelvic exams and monitor pregnancies and also criminalized abortion in a pretty draconian way. When that happened, for the first year or two, birth rates shot up; they basically doubled. But that was a very short-lived increase, and as time went on and women had the opportunity to change their plans and change their behavior knowing that was the regime, birth rates in Romania fell more or less in parallel with other middle-income countries in a similar socio-economic place. A decade or so later the birth rate in Romania was pretty close to what it was before.
I think that's a very important story because, in the face of people who would want to achieve population change through coercion, what we learn from the case of Romania is that didn't work. We also learned from the case of China's one child policy that it didn't work at coercing the population the way people think it did either. I'll have to leave the evidence on that for another day, but we find that coercion is not effective. Governments can't control the population. We believe the only way to affect falling birth rates in the long run will be by caring about what people choose and feel like they're able to choose and to combine parenting in their lives with the other things that people aspire to.
Geruso: It's really shocking how little government policy has been able to affect birth rates, and whether that is coercive policy or the sort of things that liberal social democracies do, which often amounts to giving people money, either in the form of subsidized childcare or healthcare or child tax credits or baby bonuses. These things tend to have very small effects when we can measure them at all. To the extent that policies have any measurable positive effects on birth rates, the ones that do the most — although they don’t do very much — are subsidized and organized childcare. So not merely giving somebody a check, but making sure that the product or service exists and is available.
I think we're very far away from a United States or even a world where the right conversation to have is, “How do we raise birth rates?” That's not where our attention should be. For one, the global population will continue to grow for a few decades, so this is not a crisis. We're really putting the cart before the horse when we start talking about policy when we are so far away from any sort of consensus that a world with a stabilized population at any level would be better than indefinite depopulation.
There was a comment in the Q&A that asked something like, “I’m sorry to be so blunt, but why should we avoid human extinction?” I don’t think that's a very representative view, but I think a lot of people would ask “why do we need so many people?”
Dean articulated a theory of the case of how people benefit one another. But if you want humanity to stabilize at any level, then to achieve that we would someday need to raise birth rates. Birth rates would need to come up, because whether your population is 8 billion or whether your population is 8 million, less than two children per two adults means the population will shrink in the next decade and the next and the next indefinitely. So at some level, if you want to avoid indefinite depopulation, you have to care about this. I think caring about it and understanding the facts is where the conversation should be right now. Not “what's this baby bonus going to do?”
Spears: That's why we wrote the book, because we think that more people need to be talking about this, researching this, and having conversations like this one. The place to start is to have conversations that make the case for people and ask what sort of future we should welcome so that maybe one day we will have more of a consensus on what to work together towards.