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Average life expectancy is a commonly misunderstood (and widely misrepresented) concept. We hear things like "Humans really only lived into their 40s in the Sto

Average life expectancy is a commonly misunderstood (and widely misrepresented) concept. We hear things like "Humans really only lived into their 40s in the Stone Age," or what have you. This is untrue. Average (arithmetic mean) life expectancy was a lot lower because it was heavily skewed by infant mortality. Up until very recently, many more babies died within their first few years of life. We've dramatically improved our ability to produce and distribute food and medicine, which has had a profound effect on infant survivability. But we haven't actually lengthened the average life expectancy of an adult who survives the first few years of childhood by all that much. Point is, plenty of people have been living into their 70s, 80s, and 90s for as long as we've existed as a species. That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors.

phil248 11y ago
Many more people are living in to their 70's, 80's and 90's than previously in human history. While our lifespan may not have increased much, the proportion of people reaching the extreme ends of our lifespan continues to rise. It's not just about infant mortality (not to mention death from childbirth).
- jonnathanson 11y ago
  "Many more people are living in to their 70's, 80's and 90's than previously in human history." Correct, though largely (not entirely, but very largely) because the proportion of people living past age ~3 has skyrocketed. Correct for that factor, and our life expectancy is actually lower than it was in, say, mid-Victorian England. (Note, as well, that I'm referring to life expectancy and not, say, the potential maximum human lifespan).
daveguy 11y ago
"That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors." Also somewhat owing to the recognition of Alzheimer's as a disease state (coincident with amyloid beta plaques) rather than just part of "getting old". The difference between "more prevalent" and "better identified" is difficult to determine.
- jonnathanson 11y ago
  That's a totally fair point.

phil248 11y ago

Many more people are living in to their 70's, 80's and 90's than previously in human history. While our lifespan may not have increased much, the proportion of people reaching the extreme ends of our lifespan continues to rise. It's not just about infant mortality (not to mention death from childbirth).

jonnathanson 11y ago
"Many more people are living in to their 70's, 80's and 90's than previously in human history." Correct, though largely (not entirely, but very largely) because the proportion of people living past age ~3 has skyrocketed. Correct for that factor, and our life expectancy is actually lower than it was in, say, mid-Victorian England. (Note, as well, that I'm referring to life expectancy and not, say, the potential maximum human lifespan).

daveguy 11y ago

"That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors." Also somewhat owing to the recognition of Alzheimer's as a disease state (coincident with amyloid beta plaques) rather than just part of "getting old". The difference between "more prevalent" and "better identified" is difficult to determine.

jonnathanson 11y ago
That's a totally fair point.