I personally haven't found any rhyme or reason to ages and deaths. I know they'll die younger without certain techs and without proper food supplies or diesease or injury but everyone seems different. I turned on my game one time to find a bunch of my 7 year olds dieds, couldn't figure out why either. I also have some villagers that died in their eighties (83 is the oldest I have I think).
I really just seems to depend on chance. Every villager is unique and every game is different.
However, that's just my experience, I could so easily be wrong.
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My VV2 story, "A Twist of Fate" And don't miss Krystal's stories, all three of them!
"Life is too fast... unless you're in traffic."