Back to the good old days of a 30 year life expectancy.
The 30 year business is mostly the Middle Ages to the 1800s time period. During the time period labeled the Stone Age - people lived into their 50s - 60s. During the much later Old Kingdom Egypt to Roman Empire many lived into their 70 to 90s, although, since these civilizations spanned a long period of time, there were 100-150 year spans when everything went to crap.