As a species we have doubled our life expectancy in just one hundred years. All the advances of modern life--the medical breakthroughs, the public health institutions, the rising standards of living--have given us each about twenty thousand extra days on average. There are few measures of human progress more astonishing than our increased longevity.

This book is Steven Johnson's attempt to understand where that progress came from. How many of those extra twenty thousand days came from vaccines, or the decrease in famines, or seatbelts? What are the forces that now keep us alive longer? Behind each breakthrough lies an inspiring story of cooperative innovation, of brilliant thinkers bolstered by strong systems of public support and collaborative networks.

But it is not enough simply to remind ourselves that progress is possible. How do we avoid decreases in life expectancy as our public health systems face unprecedented challenges? What current technologies or interventions that could reduce the impact of future crises are we somehow ignoring?