Fairly often, I’ve seen people misunderstand things about life expectancy. They would talk about the olden days ( Rome, for example ) , when the average life expectancy ( at birth !) could be as low as 25 years. They mistakenly thought this implied that people died around 25, that few people lived longer than that, that around 25 years your warranty ran out, like a salmon. Not so: most of the difference stemmed from higher infant mortality, and evil old farts existed and often played a key part in history. Augustus died at the age of 75, Tiberius at 77, Claudius at 63, Galba at 72 ( murdered), while Vespasian became a god at 69, baby. Certainly some emperors died young, of malaria or strangulation, but it was by no means rare for people to live into their 70s.
Narses started his successful military career at age 60, and lived to at least 86.
Even a very moderate knowledge of the past should have been sufficient to avoid this mistake: “three score and ten”, anyone?
I see a closely related mistake popping up in discussions during the current Time of Troubles. S0me people have argued that if a population’s average life expectancy is 80, while the average of those dying from coronavirus is 79 years, they’ve only lost a year of life. Not so: life expectancy at birth may be 80, but someone who is 79 has already survived all the slings and arrows that might have killed him earlier: on average he would live another 9 years or so. Misanthropic Principle. People are not built like the wonderful one-hoss shay: problems accumulate with age, but most chronic diseases do not confer a clear expiration date ( some do: we could make a pretty accurate prediction if you had pancreatic cancer, or glioblastoma.) When you hit the average life expectancy, does anything dramatic happen? Do you turn into a pile of dust that looks as if it’s been ground in the mill? “All at once and nothing first, just as bubbles do when they burst”? No way. You get up, go outside, and tell those damn kids to get off your lawn.