What is the origin of auxiliary verbs?

Question

When and why did we start using auxiliary verbs, particularly *"do"*, to ask questions and make negatives?

Answer 1

The auxiliary verbs came into play during the Middle Ages. This was a time when the English language was increasingly becoming more syndetic and reliant on clauses (note, for example, words such as "that," "do," etc. came into the English language at this point and received heavy influence from other languages, such as Latin and French). The earliest explicit usages of auxiliary verbs inflected somewhat similar to its present-day usage can be traced to the early 15th century, though this change had been underway for at least a couple series before it.