Is our eagerness to know things one of the reasons why we are so intelligent?
I think that that's one of humanity's defining characteristics. Other animals want to know "what"; humans want to know "why".
Is there a limit of intelligence your brain can hold?
There probably is some kind of limit according to how each person's brain is wired. Really intelligent people seem to involve more areas of their brain when pondering something.
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<b>"There are two means of refuge from the miseries of life: music and cats."</b>
...Albert Schweitzer