The Emergence and Development of Do-periphrasis
The emergence and development of the auxiliary do can be placed in the Middle and Early Modern English Period. Up to the fifteenth century, it was mainly used in affirmative sentences and poets employed it to meet the demands of meter and rhyme. Apart from one of its functions to add emphasis to a certain utterance, the auxiliary did not necessarily have to perform any function at all (e.g. to amend the meaning of a phrase), if it fulfilled the standards of a certain rhythmic pattern.
In the sixteenth century, the usage of the auxiliary do gained momentum. In the seventeenth century the application of do in affirmative and especially in negative questions became common, although the author of one text might not have obeyed the usage of do consistently.
Functions of Do-periphrasis
In Present-day English the auxiliary do is a frequent component in verb phrases (VP), if it is the only auxiliary in the sentence: it occurs in not-negations (She did not go to school), questions (Did she go to school?), short answers (Yes, she did), constitutes the emphatic element in affirmative sentences (She did go to school) and is employed as a “prop-word in reduced clauses” (She went to school, and I did, too) (Nevalainen 2006, 108).