> For a negative effect on health and longevity, add
> modern medicine

Modern medicine has its shortcomings, for sure. For example many people die
each year as a result of malpractice, or from the side-effects of
medications. It is however completely unfair and absurd to look only at the
negative side of medicine and conclude that modern medicine has had a
negative effect on human health. 

On balance, modern medicine has had a dramatic net positive effect on health
and longevity. 

Perhaps the most obvious and dramatic achievement of modern medicine was the
discovery of penicillin in 1928 by Alexander Fleming. Penicillin and other
antibiotics have saved millions of lives that would otherwise have been
lost. Thanks to Fleming's scientific discovery, most 
bacterial infections that were once a lethal threat are now little more than
a minor nuisance. Paleolithic shamans and medicine men would have bowed down
before Fleming and worshipped him as a god. 

-gts