Are We Approaching a Biological Limit to Human Longevity?

Abstract

Until recently human longevity records continued to grow in history, with no indication of approaching a hypothetical longevity limit. Also, earlier studies found that age-specific death rates cease to increase at advanced ages (mortality plateau) suggesting the absence of fixed limit to longevity too. In this study, we reexamine both claims with more recent and reliable data on supercentenarians (persons aged 110 years and older). We found that despite a dramatic historical increase in the number of supercentenarians, further growth of human longevity records in subsequent birth cohorts slowed down significantly and almost stopped for those born after 1879. We also found an exponential acceleration of age-specific death rates for persons older than 113 years in more recent data. Slowing down the historical progress in maximum reported age at death and accelerated growth of age-specific death rates after age 113 years in recent birth cohorts may indicate the need for more conservative estimates for future longevity records unless a scientific breakthrough in delaying aging would happen. The hypothesis of approaching a biological limit to human longevity has received some empirical support and it deserves further study and testing.

Incidence of dementia in the oldest‐old and its relationship with age: The Monzino 80‐plus population‐based study

“…Selective survival has also been indicated as a possible contributor to mortality rate deceleration at extreme age . However, this deviation from the exponential increase is a contentious topic, and the same issues related to the late‐life deceleration of mortality could affect the observed slowing down of incidence rates. Nevertheless, any attempt to relate incidence and demographic studies is heavily limited since the demographic composition of an incidence study population is inevitably not representative of that of the general population from which it derives, because the large subpopulation of prevalent cases (here 35.7%) at increased risk of mortality, is, by definition, excluded.…”

Regularities in human mortality after age 105

“…Third, our estimates are purely data driven; no model structure is imposed on the age patterns of mortality. These are three compelling features of our study that were neither achieved in previous studies of supercentenarians [12,14], nor applied to datasets where the scarcity of data was overcome by aggregating populations [10,11]. According to the hypothesis that there is a mortality plateau at extreme ages [10,17], a leveling-off in the risk of dying is expected to arise as a regularity in all the populations analyzed.…”

“…However, at the frontier of human longevity, we are challenged by the limits of demographic knowledge. The trajectory of the risk of dying at extreme old ages is one of the demographic patterns that is most often questioned in evolutionary theories of aging [2][3][4][5][6] mathematical models [7][8][9] and empirical studies [10][11][12][13][14]. The identification of regularities in mortality patterns among the oldest-old has profound implications for societies and health sciences [15], and it can radically reshape evolutionary thinking [16].…”

“…Some scholars have suggested that there is a mortality plateau after age 110, estimating a constant risk of death of 0.70 after that age, which corresponds to an annual probability of dying of about 0.5 [10,11]. Those results, however, have been questioned, based on: i) high uncertainty around the estimates, given the small number of observations (usually not exceeding 1,000 records), and ii) on the aggregation of populations, thereby masking regional and country specificity [12,14]. Recently, a sample of 3,836 Italian semi-supercentenarians (individuals aged 105 years or older) has been used to show that the risk of dying reaches or closely approaches a plateau after age 105 [17].…”

Breaking the Glass Ceiling

“…Furthermore, for such a linear increase to manifest, the rate of improvement in old age mortality must exponentially increase from one year to the other – a previously unheard-of phenomenon. A comprehensive review by Gavrilova and Gavrilov [6] highlights the trend of negligible increase of maximum reported age at death following longevity increases. Olshansky and Carnes [7] further highlight how the 30 years’ rise in life expectancy had been primarily due to easy gains in neglected areas, an expansion which cannot be repeated through more rigorous healthcare or targeting of individual aging diseases.…”