Human Longevity: Why older individuals in poorer nations outlive those in wealthier nations

forthcoming

Individuals in poorer nations generally live shorter lives than their counterparts in wealthier nations. Paradoxically, as people age, an intriguing reversal of this pattern emerges, with older individuals in certain low- and middle-income countries (LMICs) outliving those in high-income countries (HICs). Why do older people in LMICs outlive those in HICs? Why does the later-life survival advantage only occur for some LMICs? Answering these pressing questions is critical for addressing the current and future impact of aging societies and for advancing theories of the mortality transition that do not yet consider the diversity of aging experiences worldwide. LONGEVOUS has three ambitious goals and bold theoretical thrusts: (A) to assess the theoretical framework that explains the paradoxical later-life survival advantage in LMICs, (B) to assess the empirical mechanism behind low mortality at older ages in LMICs, and (C) to investigate whether this unexpected mortality paradox also emerges in terms of health outcomes. Project A tests the theory that adverse conditions over the life course create a group of robust individuals in later life. Project B develops a novel method for estimating mortality at older ages in certain LMICs, where the poor quality of age data remains unresolved and prevents us from testing mortality theories. Project C adds the health component to better understand country disparities in mortality at older ages. LONGEVOUS not only opens new perspectives for longevity research but also represents an unprecedented effort to conduct the most comprehensive study to date of the factors that shape mortality at older ages in LMICs. LONGEVOUS will use a combination of several demographic and statistical methods, and multiple data sources, including censuses, record linkage studies, and longitudinal health data. The benefit of LONGEVOUS is clear: a ground-breaking paradigm shift in our understanding of later-life survival on a global scale.