Monday, July 09, 2018

Mortality rates level off at extreme age

Interesting work from Barbi et al. showing that human death rates increase exponentially up to about age 80, then decelerate, and plateau after age 105. At that point, the odds of someone dying from one birthday to the next are roughly 50:50. This implies that there might be no natural limit to how long humans can live, contrary to the view of most demographers and biologists.:
Theories about biological limits to life span and evolutionary shaping of human longevity depend on facts about mortality at extreme ages, but these facts have remained a matter of debate. Do hazard curves typically level out into high plateaus eventually, as seen in other species, or do exponential increases persist? In this study, we estimated hazard rates from data on all inhabitants of Italy aged 105 and older between 2009 and 2015 (born 1896–1910), a total of 3836 documented cases. We observed level hazard curves, which were essentially constant beyond age 105. Our estimates are free from artifacts of aggregation that limited earlier studies and provide the best evidence to date for the existence of extreme-age mortality plateaus in humans.

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