I was thinking about dyslexic people today (just random thinking) and thus come to wonder about a few things. As you know, dyslexic people, due to certain properties of their brains, have difficulty comprehending written words. Thus dyslexia is actually a neurological limitation where the reading function is impared.
I then wondered if there exists some sort of 'advanced cognitive function' , but that this function is denied to all humans because of inherent neurological limitations. In other words, our brains are unable to process such 'advanced cognitive functions' much like how a dyslexic person is unable to discern words.
The problem is that even if some humans (maybe 1% of the population) have evolved some neural structure capable of processing the advanced function, we would still have no real evidence that such a function exists, much less being able to comprehend it. Consider an analogy, that of blind people and sighted people. The blind people have no way of verifying sight or even comprehending it (except via analogy).
Are we all crippled ? Maybe, but the frightening part is that we do not know if we are.