The article doesn't make sense to me.
They mention 1900-1938 life expectancy rose by ~5 months per generation. And then say it grew from 62 years to 80. Does that mean each generation is ~2-3 years?
What unit of measurement is that supposed to be?
Then for 1938-2000 they say it's 2.5 months per generation. If generation is 2-3 years we should already be at 100 year expectancy.
Also having 1900-1938 and 1938-2000 as the only points in time seem meaningless. Does the entire 1938-2000 have a single graident? What's the slope here?
They also mention that the main advancement in 1900-1938 is infant mortality. Which is really uninteresting for the old age.