How are pronouns resolved?

Are pronouns in English resolved syntactically or semantically? Do they always refer to the closest matching noun?

A wikipedia article has these examples:

1. We gave the bananas to the monkeys because they were hungry.
2. We gave the bananas to the monkeys because they were ripe.
3. We gave the bananas to the monkeys because they were here.

My understanding was that pronouns are resolved syntactically, and so sentence 2 is semantically incorrect (unless the author really meant that the monkeys were ripe) and sentence 3 is not ambiguous. Is this wrong?

Citations and references are most welcome.

Kosmonaut seems to be spot on: semantics are absolutely necessary for tracing back personal pronouns to their antecedents. Sentences 1 and 2 are perfectly acceptable in formal and informal English, both old and new. The same applies to most other Indo-European languages. But it is important to distinguish between the different kinds of pronouns; relative pronouns, for example, have an unmistakable syntactic link to their respective antecedents.

A. I gave some bananas to the women, who were rather hungry.

This is standard.

B. ?I gave some bananas to the women, which were larger than expected.

Somewhat bumpy, but I'd say still acceptable, because the distance between pronoun and antecedent is short, and because the pronoun "which" is restricted to inanimate objects.

C. I gave the bananas to the monkeys that were there.

Somewhat ambiguous, but, lacking strong semantic clues, the reader will not have much doubt that "that" refers to the monkeys. In speech, the use of accents could make the pronoun a bit more flexible.

D. *I gave the bananas quickly, before the storm reached the forest, to the friendly but fastidious monkeys that I had kept stored in the freezer.

Impossible, because the distance between bananas and "that" is far too great.

The first sentence makes sense to me so I am resolving that pronoun semantically. I don't think I'm unique in that regard.

Furthermore the second sentence has (at least) two potential interpretations:

We gave the bananas to the monkeys because [the bananas] were [ripe].

or

We gave the bananas to the monkeys because [the monkeys] [smelled strongly].

Most people are not going to pick the second interpretation without some other context. So semantics is extremely important in understanding the sentence and assigning meaning.

The third sentence is ambiguous. There isn't enough information to know if the bananas were conveniently located (i.e. "here") or the monkeys, or both.