Brooke Jarvis in The New Yorker:
In “Extra Life: A Short History of Living Longer” (Riverhead), Steven Johnson credits John Graunt with creating history’s first “life table”—using death data to predict how many years of remaining life a given person could expect. (One Dutch contemporary, a proto-actuary, took Graunt’s tables a bit too literally, writing confidently to his brother, “You will live to until about the age of 56 and a half. And I until 55.”) In fact, Graunt’s estimates were more of a guess than a calculation: when he wrote his treatise, in the sixteen-sixties, the Bills of Mortality didn’t record people’s age at death, and they wouldn’t for another half century. Yet his guesses about survival rates for different age groups turned out to be remarkably accurate in describing not just London at the time but humanity as a whole. For most of our long history as a species, our average life expectancy was capped at about thirty-five years.
Johnson calls this phenomenon “the long ceiling.”
More here.