The Compensation Effect of Mortality: A Global Analysis of Human Populations.

The compensation effect of mortality (CEM) refers to the convergence of mortality rates at advanced ages across different human populations. This phenomenon occurs when higher values of the Gompertz slope parameter α (actuarial aging rate) are offset (compensated) by lower values of the intercept parameter R (initial mortality rate). The age at which this convergence occurs is known as the species-specific lifespan (SSLS). The primary aim of this study is to estimate SSLS in contemporary human populations of different world regions using both parametric and nonparametric approaches. We analyzed United Nations period abridged life tables for 251 countries and regions, spanning the period from 1980 to 2020. Both parametric and nonparametric methods of SSLS estimation produced comparable results. For industrialized countries with high-quality vital statistics, SSLS estimates ranged from 95 to 100 years-consistent with estimates made more than three decades ago. This suggests that the convergence point of CEM has remained stable over time, despite substantial declines in mortality at younger ages. High SSLS estimates were also observed in regions of Eastern and South-Eastern Asia. In contrast, other world regions showed lower SSLS values, ranging from 75 to 90 years. Due to the CEM, efforts to extend lifespan are typically accompanied by a paradoxical increase in the actuarial aging rate (Gompertz slope), making significant extensions of life expectancy at older ages challenging. The CEM thus remains a key constraint to radical life extension in humans. Importantly, the compensation effect of mortality appears to be a general regularity, observed consistently across world populations examined.