because in the context you presented the comment you are referring to neurodegeneration and reduced plasticity as a normal physiological process when it is in-fact a pathological condition with an extremely complex and highly disputed etiology.
There is a great deal of research of this topic going on at your institution.......
I have actually changed coasts now...
But anyway, I think I did not make my position clear, so I will elaborate on it now. Neurodegeneration and neural plasiticity have less to do with it than my post probably implied.
I claim that stupidity and ignorance are closely linked even if we define ignorance as lack of information and stupidity as inability to solve complex problems when the necessary information is available.
The reason for this is that intelligence is genetically limited but how fully the limits will be reached depends on the environment. Which translates in practice into that - if we were able to do the following experiment: take a pair twins (exactly the same genetic material) and put one of them to be raised and work on farm, with some very basic education, limit his access to books and discourage his interest in anything remotely intelligent, while in the same we give world-class care and education to the other, from his birth until he gets his PhD, then measure their intelligence by any method you wish, I am ready to bet what the results will be.
There has been some very cool experiments with rats and mice and environmental enrichment which I can cite (i.e animals who are placed in enriched environment are smarter) and also some experiments on people which I can't cite unfortunately (which showed that if you don't use your brain for a while your IQ drops).
Anyway, I think nobody will disagree that your intelligence is highly dependent on the way you were raised, i.e. if you had to do sophisticated math when you were in 9th grade, you probably will score higher on tests if you didn't do that.
Now the thing is that the same factors (environment and education) are also decisive for your general education level. Because it can be argued (and I think it is true) that the genius is much more likely to explore the world around him than the idiot, and in the same time that same exploration of the world is critical for the development of intelligence (for the reason mentioned above).
I will be the first to admit that a lot of exceptional people in certain areas (who will no doubt score very high on IQ tests) have very poor knowledge of the world around them. However, these people are rarely the ones who will leave their names in the intellectual history of mankind, and they do not influence the general trend of overlap between smart and educated on one side and stupid and ignorant on the other.
Now for the ability to learn new things in later age (because this started the argument) - I do not argue from the point of a neuroscientist here (I am not one myself), I argue from empirical knowledge and experience. Probably I should not have used the words "the human brain", let's say that human beings in real life exhibit this trend (whatever the reasons for that)
