I once
remarked on the longevity of presidents:
The [following] graph highlights trends (such as they are) in the age at which presidents have died (or to which they have survived if still living), the age at which they were elected or succeeded to the presidency, and the number of years by which they survived (or have thus far survived) election or succession. (I have omitted assassinated presidents from the data for age of death and number of years surviving, thus the gaps in the first and third series.)
It seems to me that the early presidents were generally "healthy and wise" (and wealthy, by the standards of their time). That is, they were of superior genetic stock, relative to the average person. Their successors have tended to be of less-superior stock, and it shows in the downward trends after 1836.
The general rise in life expectancies since 1900 masks the relative inferiority of twentieth century presidents. The rising age of accession to the presidency after 1932 and the rise in years of survivorship after 1924 (both with wide variations around the trend) should not be taken to indicate that presidents of the twentieth century are on a par, genetically, with the early presidents. They are not.
These observations are consistent with the following graph of presidents' heights (here including only those men who were elected to the presidency):
Source: "Heights of United States presidents and presidential candidates" at Wikipedia.
With the notable exception of Lincoln, presidential heights generally diminished from the late 1700s to the late 1800s. The upward trend since 1900 attests to the general health and vigor of the population; it says nothing about the relative robustness of the men who have been elected to the presidency in the 20th and 21st centuries.
