If there were such a place as Shangri-La (Lost Horizon) where people did not age, would it follow that other mammals would also not age?

Mmmm, interesting question. The book and movie certainly didn’t touch on that, but I imagine all animal, insect and vegetable life in that idyllic environment would age more slowly relative to each its own natural lifespan.

I think in any world, fictional or not, it makes sense if the “rules” are consistent for all life-forms. It really depends on the cause of the slow ageing in humans. If the cause is environmental, then it surely would affect other life-forms as well. On the other hand, if it’s the result of something like genetic manipulation, then it wouldn’t.

Hmmm. Ok so there is a self sustaining biosphere orbiting the earth at speeds approaching that of light. Since as speed increases time slows to the outside observer if there were humans living in said biosphere many years on earth would pass where as only a few would pass on the biosphere. In that regard I suppose you could have “a 200 year old guy eating a 60 year old tomato”. It’s all relative.

Well I could buy into mammals and insects et al having a longer life span. But plants produce are generally seasonally based so the only way to prolong their life is to lengthen the seasons or dramatically change the nature of plant reproduction.

In scenario number one we still wouldn’t be 200 years eating a 60 year old tomato. Maybe the length of time would be equivalent.

In scenario number 2 following consistent rules the reproduction of each species would change. Be pregnant for years instead of 10 months. Development would be slowed down. Which brings to mind slow motion.