Ok, so lets assume these are facts. Year 1900 Life expectancy: 47 World population: 1.6 Billion Year 1950 Life expectancy: 65 World population: 2.5 Billion Year 2000 Life expectancy: 78 World population: 6.1 Billion Going by these statistics, cancer rates have to increase. And if 70 is the magical age to start getting cancer, well humans weren't expected to live that long not so long ago. Couldn't find that patent on volcano's and natural bush fires. Might be still up for grabs. Dead wildlife might argue with the latter part of your statement.