[philwelch]

Is that actually true?

Life expectancy is a bit of a misleading metric in that regard, since life expectancies are just averages. If a population has a life expectancy of 50, that doesn’t necessarily mean that 50-year-olds are dying of old age and no one makes it to age 80. It could mean that there are a lot more children and young adults dying and bringing down the average. So if you’re living in a society with a life expectancy of 50 years and you turn 50, your personal life expectancy is probably going to be closer to 70-80 because you’ve already managed to survive the causes of death that affect younger people.

And you may very well develop things like dementia. The concept of people becoming elderly enough to lose their mental faculties isn’t some unprecedented 20th century discovery. It is becoming more common, but that’s just because deaths from childhood illness, infectious disease, violence, and occupational accidents are becoming less common.