We already have ageism enshrined in our constitution with minimum ages. If that's OK, then we should have upper age limits as well.
The lack of an upper age limit is potentially far more damaging in the modern era than not having a lower age limit. People in the founding fathers' times didn't live into senility, if you made it to 60 you were doing pretty good and probably not going to make it for another 3 decades. We have had at least one definitely senile president in the last 30 years and the evidence strongly suggests our current one is suffering from dementia as well. The two leading Democratic presidential candidates are both 80+ years old and one of them is looking awfully senile in public too. Dementia is a serious threat to American democracy in the modern era.
The structure of the American political system means that the people most likely to make a successful run are the ones that have spent 30-40 years building political capital, and those are inherently the oldest among us. Without some form of check, you end up with rule by octogenarian which is where we are.
What's the average age of a Senator these days? 65 or so? And that is the most likely place a presidential campaign can be launched from. And you would want to be a senior senator to be able to beat out the other senators...
The average age of the 1st Congress (1789) was 46.[1] The average age of the 50th Congress (1887) was 57.[2] The average age of the 115th Congress (2018) is 61.[3]
That's not a terribly huge change, especially considering the increase in age of the population.
Respectfully, I think you are making a "classic" mistake in demographics — one of the most counter-intuitive discipline I ever studied.
One TL;DR is that averages give you very, very, very partial information — without at least a median and the standard deviation, it's pretty much meaningless. Math, but applied to stats / demo yields incredibly wrong pictures if you don't look deeper. Think structure, not KPI, and longitudinal trends — what you see today isn't what's "now", a lot of it is what was set up 20, 50, 60 years ago.
Another TL;DR is that the increase in life expectancy is seldom about "how long do people live" but rather "how many of us die too early" — and this is where the fantastic increase in average comes from. The end-of-life expectancy sure rose too, but much less, and is actually starting to fall back down in the US (some other countries too, it's not just Sam, but it's not a generality either).
Thus the ageing of Senators has little correlation with life expectancy, it's a false correlation (again evidenced by biological facts). From a political science / historical standpoint, current epoch looks a lot like e.g. the second half of the Roman Empire ("decadence", although the word is way too negatively connoted if we mean to judge these times through a modern lens — stagnant in influence is more like it, ageing and eating well is another take).
Judging by intuition from having looked at these figures, I'd say the average political apparatus is 20+ years older today than it used to be around the revolution relatively to the active population, in terms of general pyramidal structure (so, beyond averages). Again, not true in all countries — some are even trending younger in Europe, which is about a couple decades ahead of the USA in terms of demographic structure.
Sorry I can't write a book for each of these TL;DR, but the knowledge on how to analyze demographics is there if you Google it.
I don't have the time, inclination, nor skill to do a proper analysis. I've already contributed some empirical substance; feel free to do the same. But I will make two comments: 1) life expectancy excluding infant mortality has indeed gone up considerably since 1789, by about 10-15 years, give or take, according to the particular source. 2) I would expect more old-age outliers today than 1887 driving up the average, so I wouldn't be surprised if the mean is lower or about the same as 1887. But I'll leave it to somebody else to crunch those numbers. Here they are, FWIW:
I now realize my comment may be read as midly abrasive and perhaps condescending. Please receive my apologies, it was not my intent.
I won't debate your arguments because frankly I don't know, and your guess is as good as mine (you do make sense, I personally follow you intuitively; I just happen to see some interpretations of demographics that bit me in the past, in particular this topic of life expectancy).
For instance on the topic of Senators, if you just look at the pyramid of ages for the US, there's this big huge boomer zone — look no further to explain their overpresence in every domain where their current age, i.e. old, is an asset. (However, that there are two or ten times more seniors today than in 1800, when less than 1% of 1% of the population is a Senator-grade politician, is insignificant numerically.)
Let's ask ourselves the question, are all experts in all professions generally older today than before? Are Senators evolving like other comparable 'sectors' of activity? (academia, consulting maybe, etc) And I think that yes, as there are a lot of boomers, and they're here to stay to the end of their maximum lifespan because they're so many and Senator is a rare job.
The lack of an upper age limit is potentially far more damaging in the modern era than not having a lower age limit. People in the founding fathers' times didn't live into senility, if you made it to 60 you were doing pretty good and probably not going to make it for another 3 decades. We have had at least one definitely senile president in the last 30 years and the evidence strongly suggests our current one is suffering from dementia as well. The two leading Democratic presidential candidates are both 80+ years old and one of them is looking awfully senile in public too. Dementia is a serious threat to American democracy in the modern era.
The structure of the American political system means that the people most likely to make a successful run are the ones that have spent 30-40 years building political capital, and those are inherently the oldest among us. Without some form of check, you end up with rule by octogenarian which is where we are.
What's the average age of a Senator these days? 65 or so? And that is the most likely place a presidential campaign can be launched from. And you would want to be a senior senator to be able to beat out the other senators...