The decline of human mortality is a unique phenomenon that distinguishes the evolution of from that of other species. In the short span of two hundred or so years, human life expectancy at birth increased from roughly 30 years to values exceeding 85 years, well past the ages of reproduction.

Although there is substantial diversity, most human populations have shared in this progress, largely attributable to a scientific revolution and a cascade of technological breakthroughs that the explosive growth of scientific knowledge has made possible. Will past gains in survival continue to accrue, even if at substantially reduced rates? Barring natural disasters, wars or epidemics, will universal improvements in human life expectancy continue in the short and medium run?