Demographic perspectives on the rise of longevity

Background: This article reviews findings about the rise of life expectancy, current levels of life expectancy in countries with high life expectancies, and possible future trends in life expectancy. Maximum lifespans and the equality of lifespans are also considered. Methods: Demographic data on age-specific mortality are used to estimate life expectancy. Validated data on exceptional lifespans are used to study the maximum length of life. Findings of the most significant publications are critically summarized.Results: In the countries doing best, life expectancy started to increase around 1840 at a pace of almost 2.5 years per decade. This trend has continued until the present. Contrary to classical evolutionary theories of senescence and contrary to the predictions of many experts, the frontier of survival is advancing to higher ages. Furthermore, lifespans are becoming more equal, with octogenarians and nonagenarians accounting for most deaths in countries with high life expectancy. Extrapolation of the trend indicates that most children born this millennium will celebrate their 100th birthdays. Considerable uncertainty, however, clouds forecasts of life expectancy and maximum lifespans: life expectancy and maximum lifespan might increase very little if at all or longevity might rise much faster than in the past. Conclusions: Substantial progress has been made over the past three decades in deepening understanding of how long humans have lived and have long they might live. The social, economic, health, cultural and political consequences of further increases in longevity are so significant that the development of more powerful methods of forecasting is a priority.