As I wrote in that post, there are some factors that lead to us thinking longer lives would be better, and others that shorter would be better.
Maybe this is easier to think about with a related question: what is the ideal length of tenure at a company? Do companies do best when they have entirely employees-for-life, or is it helpful to have some churn? (Ignoring that people can come in with useful relevant knowledge they got working elsewhere.) Clearly too much churn is very bad for the company, but introducing new people to your practices and teaching them help you adapt and modernize, while if everyone has been there forever it can be hard to make adjustments to changing situations.
The main issue is that people tend to fixate some on what they learn when they're younger, so if people get much older on average then it would be harder to make progress.
what is the ideal length of tenure at a company?
A rather important question here is what's "ideal" and from whose point of view? From the point of the view of the company, sure, you want some churn, but I don't know what the company would correspond to in the discussion of the aging of humanity. You're likely thinking about "society", but as opposed to companies societies do not and should not optimize for profit (or even GDP) at any cost. It's not that hard to get to the "put your old geezers on ice floes and push them off into...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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