Demographic perspectives on the rise of longevity

Abstract

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.

Short-term forecasts of expected deaths

“…It is not possible to pinpoint the date of the death of an individual or the cause of death, because the cause has immediate, proximate, underlying, and earlier-life components and hinges not only on an individual’s personal characteristics but also on availability and excellence of medical care, air quality, family and social networks, and many other factors ( 30 ). It is, however, feasible—and this is a remarkable achievement of demography—to forecast death counts by age and sex in a population in the short term and, with decreasing accuracy, in the medium and long term ( 31 ). Furthermore, informative forecasts can be made of how many deaths would have occurred if some major change in mortality conditions had not happened.…”

The long lives of primates and the ‘invariant rate of ageing’ hypothesis

“…These gains have resulted from shifting the majority of deaths from early to later and later ages, with no evidence of slowing the rate at which mortality increases with age (i.e. the 'rate of ageing') [2][3][4] . Further substantial extensions of human longevity will depend on whether it is possible to slow the rate of ageing or otherwise reduce late life mortality.…”

Reduction in the 2020 Life Expectancy in Brazil after COVID-19

“…Between 1945 and 2020, life expectancy at birth in Brazil increased from 45.5 to 76.7 (9) , an average of almost five months per calendar year. This relatively fast pace characterized many countries that had been lagging their peers in mortality improvement and subsequently benefitted from their forerunners’ progress (8, 10) .…”