I'm curious about the state of research on longevity for model organisms. Especially C-Elegans, or something else comparatively "simple" to a human. If we can't manipulate lifespan significantly in those, I don't see much hope for it in humans. Phrased a different way: I think extending flatworm lifespan is a prerequisite for extending human lifespan, at least in a systematic way.
I'm not optimistic we'll have real breakthroughs in this field within the next century or so, but the gut reactions to the field (See the acerbic tone of the linked article) are born more out of a knee-jerk reaction to what longevity research implies, than a rational take. When the arguments go towards societal sustainability or "I wouldn't want to live any longer than 90", it's a cue you're reading a skin-deep reaction.
We have good results for c. elegans, mice, and fruit flies. These have all had their lifespans extended by quite a lot for c. elegans, or iirc about 40% for mice.
This, and the existence of several multicellular organisms that do not appear to age, is the basis for optimism for eventual success in extending healthspan. Like, so far we haven't found any fundamental biological reason that living longer is impossible.
(it is worth nothing that Blagosklonny's paradigm of programmed aging seems to me to lead to more pessimism, but I don't know if he'd agree)
Matt Kaeberlein's Dog Project, and Celine Halioua's company Loyal, are both focused on extending dog lifespan, as a much larger model organism, but are not there yet.
You might be interested in this paper, "A collective analysis of lifespan-extending compounds in diverse model organisms.[1]" Interestingly, common substances like aspirin and minocycline had a large impact on lifespan in the simple organisms studies. This seems to be due to a systemic impact on the organism's function and ability to heal from age related degeneration.
Experimenters have been able to extend the lifespan of C-Elegans five-fold by modifying just a few genes[0], though its unlikely that research will translate well to humans. Even interventions in much more closely related mouse models frequently fail to translate to us, but must biologists will agree with you that those organisms are the place to start.
I'm not optimistic we'll have real breakthroughs in this field within the next century or so, but the gut reactions to the field (See the acerbic tone of the linked article) are born more out of a knee-jerk reaction to what longevity research implies, than a rational take. When the arguments go towards societal sustainability or "I wouldn't want to live any longer than 90", it's a cue you're reading a skin-deep reaction.