Originally Posted by Sage Rat
is a bit better testament to the output of the Age of Reason.
It should be noted that until the modern era, the distribution of the age at death was strongly bimodal, with a high infant mortality, a reasonably low youth and middle-age mortality, and then, of course, full old-age mortality. ('Bimodal' means a graph would have two peaks, meaning there are two
numbers or ranges of numbers that are almost equally common (the mode). This is the classic 'bathtub curve
'. Bimodal distributions don't play well with methods to get a single number for an average.) The high infant mortality throws people, because the naïve arithmetic mean used to determine a single number for life expectancy implies a lot of 20- or 30-year-olds were dying off back then. Obviously not the case. Remember that the Founding Fathers were living well into their 70s and 80s back in the 1800s, well before modern medical practice.