First - I just want to say that this is what I have gathered from talking to people for a while. I have no scientific basis for it.
I have gotten the impression that 10-15 years is a pretty good life span for them in captivity. Now, if 50 is a possibility, that 10-15 sounds terribly low, so I am really not sure. I had Archimedes for almost 10 when he had to be put down due to cancer, but he was not a baby when I got him, and I long since had decided that the place I had gotten him had told me a fictional story about his background. I am guessing he was 10-12 when he died. However for the 1-2 (guessing) years before me I suspect he did not receive ideal care or attention.
Just my thoughts. (::sigh:: How I miss him)
Elizabeth

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1.0 Mali Uro Archimedes (May he rest in peace)
0.0.1 Egyptian Uro Zuberi Mosca Khu (Mosca)
0.0 Fish
0.1 Sulcata Minnie
1.1 Iguanas Flik and Loki
0.1 Newfoundland Jasmine (RIP)
0.1 Feline Winter
Indiana & Wisconsin