I submitted this because there is a giant statistical error in the article that is worth noting:
For example, the average age of the first eight presidents at their time of death was 79.8 years - during a time when life expectancy at birth for men was less than 40.
A really common error. Also pops up in debates over pensions. While it is true that people tend to live longer post-retirement now than they used to, and that this impacts pension-fund economics, many people quote life expectancy at birth to illustrate the difference, which isn't really relevant, since infant mortality rates are not closely related to pension-fund solvency. (Conditional life expectancy at typical retirement age would be the right statistic.)
Olshansky admits that "All of these presidents benefited from the trifecta of exceptional wealth, almost all were highly educated and all of them had access to medical care," and yet he decided to compare them to a 'cohort' consisting of the general population.