Why is 50 considered "middle age"? That implies life expectancy of 100. I would say 40 is middle age. Regardless, I applaud the work on trying to increase fl

Why is 50 considered "middle age"? That implies life expectancy of 100. I would say 40 is middle age. Regardless, I applaud the work on trying to increase fluid intelligence. It's a truly hard problem and if humanity can crack it we would all be better off for it. Sometimes we focus so much on AI that we forget that we already have about 7 billion human intelligences, most of which are severely underutilized.