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Name: Daniel
Status: other
Grade: other
Location: AZ
Country: N/A
Date: 4/20/2005

My girl friend and I got into a discussion about life spans of humans, both historically and geographically. I have two basic questions. First, do humans live longer now I comparison to 2000 years ago? Next, what is the life span difference between a city dweller and say a South American Indian living in the rain forest (not in houses)? if you can help me answer this we would both appreciate the help.

It depends on what parameters you place on life span...average or maximum. Average life span has dramatically increased over the past two thousand years. Average life span can be lowered by a host of factors some of which in modern times have been dramatically reduced. 2000 years ago average life span is believed, by most, to have been in the 20's. This was in part because of such things as, starvation, disease, and high infant mortality. Even in the 1700's in the US it was still in the 20's. The 19th and 20th century saw the most dramatic rise in average life span. Clean water for cities, reduction in infant mortality and improvements in medical intervention (e.g., antibiotics) played large roles.

Maximum life span is far more challenging to find. Since I got my Ph.D. in this field, it has been somewhat of a controversy but most estimates of it seem to have been rising over the past 20 years. In the journal* Science* a few years ago there was an article on the "oldest" living humans (documented) and I believe they were on the island of Sardinia. I think there is NO limit to maximum human life span. In the future, it will be more and more feasible to replace or rejuvenate "worn out" organs or organ systems to keep a person alive. Consider if you will the possibility of downloading the entire memories and personality of a human into a computer and then uploading this into a human whose mind is a void...far out...but possible. It just depends what you might consider an individual or human. As a biologist for over 30 years, I still have not found a satisfactory definition for an individual or even life.


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