The life span in 1949, India was 32.5 years old. Goes back to what Coelho said, outside forces.. Disease plays a major factor, even if the Indians were smoking a ton of weed they were still starving and had a literacy rate of 17 percent.. There is no such thing as a miracle cure all drug, from my understanding cannabis will help specific conditions [ and symptoms ].. Some of these conditions probally were discovered after cannabis. It cannot cure EVERY disease, feed, educate, and build proper houses. However, this is no reason to disregaurd it's medicinal value.

The industrial revolution came about, as well.. Which played a role in average life span of people. Look at Africa for example, there is weed there.. Still, the death rate is high. Smoking a bowl won't save them from Malaria, AIDS, droughts, lack of transportation and road system.. Not to mention 15 landlocked countries. IMHO weed probally hasen't played much of a factor in the average life span, there are much more considerable factors..