23 could be a bona fide mid-life crisis in the 17th century :)
http://www.infoplease.com/ipa/A0005140.html
So the average 20 year old in 1850 could expect to live an additional 40 years, to roughly age 60. The curve started flattening after WW1 and continued doing so until around the 70s and 80s.
Here's hoping for the hockey stick.
I suspect there were significant differences in life expectancy between the 17th century and 1850.