This can be extended even further - hunter-gatherers never retired either. However in both cases people did actually _retire_ from direct activity. Elders would often become advisors and community nurturers rather than actively milking cows, hunting deer and whatnot.

I think here what becomes apparent is that it's not loss of specific activity (work) that causes the decline but activity in general which is very much duuuh - obviously.

Based on my grandmothers I’d say they mostly sat around and gossiped, went on walks together, ate meals together, did fun stuff together and then talked about stuff. Repeat until they die off.

Socializing with friends every day can be very fulfilling and doesn’t require to actually produce anything or do any work.