A simple three word question like, "Do I go," demonstrates Four Transformational rules.
Notice that there is a required order to these modals. You can't say, "I not do go."
And now, to change "I do not go," into a question, we must move both modals to the front, as in "Do not I go?" But its rare in conversational speech to say it that way. We usually contract the modals "do" and "not" (transformation #4) and say, "Don't I..."
The point here is that if a child spontaneously (i.e, is not simply mimicking someone else) generates the three word sentence, "Don't I go," look at the wealth of linguistic knowledge that has been demonstrated here!
In addition to the lexicon, there has been demonstrated four transformational rules and the observance of the proper word order in the sentence, and within the modals. These rules would be lacking the sentences made by Koko, the Gorilla.