Global birth rates are collapsing—sometimes to half the level needed to keep populations stable. UT-Austin’s Michael Geruso explains how that trend could shrink the world’s population from eight billion to three billion in just three generations. He unpacks the silent drivers behind falling fertility, why cash incentives rarely work, and what disappearing people mean for innovation, cities, pensions, and geopolitical power. 

If you’ve never worried about a world that’s too small, this conversation will change your mind.