For years, the world worried about overpopulation and our capacity to sustain ever-increasing numbers of people. Now, the worry is underpopulation—and recent numbers are stunning. Fertility rate is the average number of children that are born to a woman over her lifetime. According to the United Nations, this number is currently 1.64 in the U.S.: If it stays this way, in three generations there will only be half as many young Americans as there are today, holding immigration constant. In China, this number is even lower: one child per woman. Just eight countries are expected to account for more than half the rise in global population between now and 2050.

Economic theory is based on the idea of expansion, and humanity has been expanding since 1500. If that is about to change, then the very foundation of our economic theory will need rethinking.

Acclaimed author, historian, and filmmaker Sir Niall Ferguson (Stanford/Harvard) joins Bethany and Luigi to discuss why we're heading toward a global population decline and what it all means for civilization. They discuss how factors like climate change, immigration, reproductive rights, artificial intelligence, and the trade-offs women face between career and motherhood are influencing decisions to have children. What are the implications of falling birth rates not just for the market economy but also for geopolitics and intergenerational conflict? Can we reverse trends in fertility before it is too late?