<p>In the wild, pygmy chimpanzees are found only in an inaccessible region south of the Zaire River, and so no more than a few are in captivity.</p>
<p>why is this?</p>
<p>What about it? If it's an error in the sentence, I'd assume it's the and right after the last comma that's messing it up.</p>
<p>Sorry I don't have a blue book on me, that's just what I'd guess.</p>
<p>There are two key points.
One: The sentence must be one. I mean that since the clauses are linked by a comma, only one continuous idea is allowed. </p>
<p>And because of so,
Two: This is a cause and effect sentence. "And so" is the link.</p>