> The authors also observed a role of random chance in grammatical change. The periphrastic "do," as used in, "Do they say?" or "They do not say," did not exist 800 years ago. Back in the 1400s, these sentiments would have been expressed as, "Say they?" or "They say not."
Using the Penn Parsed Corpora of Historical English, which includes 7 million syntactically parsed words from 1,220 British English texts, the researchers found that the use of the periphrastic "do" emerged in two stages, first in questions ("Don't they say?") around the 1500s, and then roughly 200 years later in imperati…