That never existed (except in gun free zones in Chicago). You are looking at average life span, one of the worst myths spun by Big Pharma.
Back before we knew to wash our hands, when we had higher incidences of death during childbirth (and in the days before abortions), we had people dying at age 15 and age 0, mother and child respectively. That brought the average life span down. But when we exclude those, we see that people who didn't die during childbirth lived to be age 70 or 80 - same as now - and without Big Pharma drugs. Men tended to be nearly as productive as their prime until they eventually would drop dead and/or be taken out to pasture to die.
