The World Might Actually Run Out of People
You traveled all over the globe to interview people for this book. What’s one image or conversation that really made the statistics jump off the page?
DB: There was a moment when we were sitting in this little school in Srinivaspuri, listening to a focus group of 13 or 14 women who lived there. And I kept seeing this faint glow light up under their saris. I didn’t know what it was. And then I saw one woman reach in and pull out a smartphone, look at it, and put it back. And I realized, here we are in a slum in Delhi, and all these women have smartphones. Who can read. Who have data packages. And I was thinking, they have all of human knowledge in their hands now. What’s the impact of that going to be?
Well, what is it?
DB: So, the UN forecasting model inputs three things: fertility rates, migration rates, and death rates. It doesn’t take into account the expansion of education for females or the speed of urbanization (which are in some ways linked). The UN says they’re already baked into the numbers. But when I went and interviewed [the demographer] Wolfgang Lutz in Vienna, which was one of the first things we did, he walked me through his projections, and I walked out of the room gobsmacked. All he was doing was adding one new variable to the forecast: the level of improvement in female education. And he comes up with a much lower number for global population in 2100, somewhere between 8 billion and 9 billion.
JI: Lutz has this saying that the most important reproductive organ for human beings is your mind. That if you change how someone thinks about reproduction, you change everything. Based on his analysis, the single biggest effect on fertility is the education of women. The UN has a grim view of Africa. It doesn’t predict much change in terms of fertility over the first quarter of the century. But large parts of African are urbanizing at two times the rate of the global average. If you go to Kenya today, women have the same elementary education levels as men. As many girls as boys are sitting for graduation exams. So we’re not prepared to predict that Africa will stagnate in rural poverty for the rest of the century.
DB: And that’s just one cultural variable. So you can say that the old models always worked in the past, but what if the past is not prologue? What if we’re moving into a different cultural moment? What if it’s accelerating? And what if that cultural moment really is about the personal decisions women make about their lives?
JI: We polled 26 countries asking women how many kids they want, and no matter where you go the answer tends to be around two. The external forces that used to dictate people having bigger families are disappearing everywhere. And that's happening fastest in developing countries. In the Philippines, for example, fertility rates dropped from 3.7 percent to 2.7 percent from 2003 to 2018. That's a whole kid in 15 years. In the US, that change happened much more slowly, from about 1800 to the end of the Baby Boom. So that’s the scenario we’re asking people to contemplate.
You traveled all over the globe to interview people for this book. What’s one image or conversation that really made the statistics jump off the page?
DB: There was a moment when we were sitting in this little school in Srinivaspuri, listening to a focus group of 13 or 14 women who lived there. And I kept seeing this faint glow light up under their saris. I didn’t know what it was. And then I saw one woman reach in and pull out a smartphone, look at it, and put it back. And I realized, here we are in a slum in Delhi, and all these women have smartphones. Who can read. Who have data packages. And I was thinking, they have all of human knowledge in their hands now. What’s the impact of that going to be?
Well, what is it?
DB: So, the UN forecasting model inputs three things: fertility rates, migration rates, and death rates. It doesn’t take into account the expansion of education for females or the speed of urbanization (which are in some ways linked). The UN says they’re already baked into the numbers. But when I went and interviewed [the demographer] Wolfgang Lutz in Vienna, which was one of the first things we did, he walked me through his projections, and I walked out of the room gobsmacked. All he was doing was adding one new variable to the forecast: the level of improvement in female education. And he comes up with a much lower number for global population in 2100, somewhere between 8 billion and 9 billion.
JI: Lutz has this saying that the most important reproductive organ for human beings is your mind. That if you change how someone thinks about reproduction, you change everything. Based on his analysis, the single biggest effect on fertility is the education of women. The UN has a grim view of Africa. It doesn’t predict much change in terms of fertility over the first quarter of the century. But large parts of African are urbanizing at two times the rate of the global average. If you go to Kenya today, women have the same elementary education levels as men. As many girls as boys are sitting for graduation exams. So we’re not prepared to predict that Africa will stagnate in rural poverty for the rest of the century.
DB: And that’s just one cultural variable. So you can say that the old models always worked in the past, but what if the past is not prologue? What if we’re moving into a different cultural moment? What if it’s accelerating? And what if that cultural moment really is about the personal decisions women make about their lives?
JI: We polled 26 countries asking women how many kids they want, and no matter where you go the answer tends to be around two. The external forces that used to dictate people having bigger families are disappearing everywhere. And that's happening fastest in developing countries. In the Philippines, for example, fertility rates dropped from 3.7 percent to 2.7 percent from 2003 to 2018. That's a whole kid in 15 years. In the US, that change happened much more slowly, from about 1800 to the end of the Baby Boom. So that’s the scenario we’re asking people to contemplate.
