The clinical cutoff for the mental cripple is an IQ of 70. Flynn noticed that the average - normed to IQ 100 - is getting smarter. There's a qualitative cutoff at the mental cripple stage. Such a person is literally too stupid to support themselves, and require lifelong care. Basically, childcare extends across adulthood.
Setting aside edge cases (which can be statistically smoothed out) is the cutoff actually dropping, as the Flynn effect would predict?