When population is growing rapidly, the average age is fairly young. When population growth slows or turns negative, the average age rises sharply. Per a Stanford Study, when SS was established in 1935 life expectancy was just 61 (meaning that the few recipients were already past their life expectancy when they got their first checks).
I do want to make a comment on this... And I'm sure you know the subtlety, but "life expectancy" is a concept that I think is woefully misunderstood.
Quoted life expectancy numbers are typically "life expectancy at birth". Which includes all possible causes of death.
But a lot of times I hear people looking it as if people who outlived that number have done something strange. I.e. in 1787 average white male life expectancy at birth was 38 years. So our brains naturally assume that living much past 38 was rare and people at that age are ready to kick the bucket... But that wasn't true. What it means is that there were all sorts of ways to die at a young age that brought the AVERAGE down, but if you avoided those horrible things and make it to 18 years old, it doesn't mean you should only expect to live 20 more years. And if you're 30 years old, it doesn't mean you shouldn't expect to live more than 8 more years.
A good example is this:
https://www.annuityadvantage.com/resources/life-expectancy-tables/- If you're born today in America your life expectancy as a male at birth is 76.04 years.
- If you're 18 years old in 2020, your life expectancy increases to 76.81 years.
- If you're 40 years old in 2020, your life expectancy increases to 78.59 years.
- If you're 65 years old in 2020, your life expectancy increases to 82.92 years.
The more you avoid dying from horrible disease, accident, murder, war, etc, the more your own personal life expectancy extends beyond the average on the day you were born.
So the distinction that most people don't understand is that in 1935, when average life expectancy at birth was 61 years, that most 65 year olds were on their deathbeds or anything like that. Most 65 year olds probably had an expectation of living >10 additional years or more at that time. But because the average was 61, the proportion of the population >65 years old was MUCH lower than it is today when the average is 76 years...
Again, Medina, I know you get the distinction here... But I wanted to post it because I think a lot of people don't look at "life expectancy" numbers properly.