J.N. Adams takes up a classic question about the history of Latin in his Social Variation and the Latin Language: How did the Romance languages emerge from Latin?
It’s been thought that the Romance languages came from changes in Latin pronunciation and grammar at the lower levels of Roman society. Adams examines this thesis in detail, and concludes that it is basically right, though he adds nuance. As Roy Gibson says in his TLS review, “A good number of features of Romance are in fact the results of changes which affected Latin in general, while others are demonstrably the product of elite usage. The use of the present tense to refer to the future, so common in Romance languages, can be found across the social spectrum of Latin, from letters scratched by uneducated users on shards of pottery to the literary texts of such renowned fastidious stylists as Julius Caesar.”
Adams shows that there was variation even within “elite” Latin. As Gibson summarizes, “A modern university education in Latin, with its inevitable concentration on the literary classics of Augustan Rome, is apt to make the language appear monolithic, decorous, unchanging. Who could have guessed that the phrase cum nos (‘when we’) was to be avoided in polite speech, since the common assimilation of final ‘-m’ into the following consonant turned the inoffensive phrase into Latin’s own version of the c-word (cunnos)? Or that many Italians eventually fell into the habit of saying ozie for hodie (‘today’), and that diebus (‘days’) might be pronounced zebus?”
Theological concerns enter into the story too. Gibson writes, “If Social Variation has a hero to offset the grammarians of late antiquity, it is in fact St Augustine. The Saint sternly noted that ‘the sons of men carefully observe the rules of letters and syllables received from former speakers, and neglect the eternal rules of everlasting salvation.’ In his quest to elevate eternal life over grammatical correctness, Augustine insisted that elite speakers of Latin within the Church must adapt their speech to the social level of their audience. But this did not mean that anything could go. The Latin term dominus (‘master’) may have been undergoing syncopation to domnus already in the Classical period (a development with clear outcomes in Romance languages), but Christians were not happy for the abbreviated term to be applied to their God. Emperors, clerics and even saints might be referred to as domnus, but the Deity must be addressed with all three original syllables” - homage to the Trinitarian nature of the Dominus, perhaps?