[nogabebop23]

We seem to pack most of our learning into the first quarter or third of our life, then taper off to almost nothing. That doesn't work for maintaining anything, so why would we think our ability to learn is any different? The physiological deterioration may be inevitable in some ways, but there are definitely other factors at play like habits, motivation, opportunity and lots more. Your example with your dad is incredibly rare in the general population, but probably a pretty common path amongst 67-yr-olds writing giant code bases, or 74-yr-olds still in programming jobs. I don't see it as defeating death as much as extracting everything out of life. Maybe the other side of the same coin?