In 1920, at the end of the last major pandemic, global life expectancy was just over forty years. Today, in many parts of the world, human beings can expect to live more than eighty years. As a species we have doubled our life expectancy in just one century. There are few measures of human progress more astonishing than this increased longevity.Extra Life is Steven Johnson’s attempt to understand where that progress came from, telling the epic story of one of humanity’s greatest achievements. How many of those extra years 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, and of dedicated activists fighting for meaningful reform.But for all its focus on positive change, this book is also a reminder that meaningful gaps in life expectancy still exist, and that new threats loom on the horizon, as the COVID-19 pandemic has made clear. 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?A study in how meaningful change happens in society, Extra Life celebrates the enduring power of common goals and public resources, and the heroes of public health and medicine too often ignored in popular accounts of our history. This is the sweeping story of a revolution with immense public and personal consequences: the doubling of the human life span.