In this article, http://geography.about.com/od/populationgeography/a/lifeexpectancy.htm (and I've also heard it elsewhere), the world life expectancy averages about 30.
However, an arbitary search of wikipedia of random people I know lived and died (of natural causes) before the 20th century shows that almost all of them died over 30.
Also, I was in an old cemetery the other day, and saw that very few of the people buried there pre-1900 was under 30 years.
So I understand my 'research' is purely unscientific and to be on wikipedia you have to be famous, which means you probably were wealthy, which means you probably increased your chances of living longer.
Still, it's hard to imagine a world where 30 is the life expectancy - that means that would be the average and half the people would live to be under 30 before dying.
I would like to hear further evidence supporting this fact or explanation for the fact.
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