1400 assuming ideal conditions (as in no plagues, wars, disasters) and in places that use either advanced technology to improve living conditions (maybe a toothbrush?
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) or magic to help reinforce the body.
Unfortunately, 1400 years is a long time, and it is almost guaranteed that there will be several wars, horrible diseases, or natural disasters that can ruin the lives of many people. And if you've lived a few hundred years, some people find no reason to keep on living. Dying of old age is very rare.
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"I hate that! Your answers are always short, precise, and utterly useless!"
"Yes."
"Sometimes I get confused whether I'm posting on ATT or in the War Room. But then I remind myself: If it's moderators acting scatter-brained and foolish, then it's the War Room*.
*Unless it's Avatara, of course."
-- From the memoirs of Sundered Angel