Economist Dean Spears explains the forces driving global population change, from past fears of overpopulation to today's concerns about declining birth rates.

He contrasts the perspectives of biologists and economists on population growth and highlights the role of human ideas and innovation in sustaining progress. Spears also discusses misconceptions about zero-sum economics, the links between population, health, and economic well-being, and the rise of anti-natalism.

The conversation covers population size and environmental concerns, government policies on family planning, and why cultural attitudes toward reproduction may be as important as policy in addressing the challenges of a shrinking population.

Dean Spears is an economist, demographer, and associate professor at the University of Texas at Austin. Spears is a founding executive director of r.i.c.e, (a research institute for compassionate economics), a nonprofit that works to promote children's health, growth, and survival in rural India. Together with Michael Geruso, he is the author of the new book After the Spike: Population, Progress, and the Case for People.