I think you don't have a clear picture of how highly functional low IQ people can be.
But how highly functional are low-IQ people on average? Looking at only the most functional low-IQ people wouldn't give a good idea of what to expect in general.
But how well would a 13 year score compared to 18 year old on a IQ test? Not that well I suspect.
The 13-year-old's raw score would generally be lower, but their IQ should be about the same as the 18-year-old's; IQ tests are age-normed nowadays.
But how highly functional are low-IQ people on average? Looking at only the most functional low-IQ people wouldn't give a good idea of what to expect in general.
My point was that different groups of people that might score low on IQ tests sometimes differ systematically from each other. In my last paragraph I suggest quite directly IQ 70 Black people are different from IQ 70 Whites and East Asians.
The 13-year-old's raw score would generally be lower, but their IQ should be about the same as the 18-year-old's; IQ tests are age-normed nowadays.
Well a...
Please remember to have no heroes or villains, but this just looks plain bad to be honest. I'm lowering my estimation of the quality of Stephen J. Gould's work in this area.
USA today:
Haha. Humans.
The paper itself: