To be clear, there’s no way the idea of “two becoming one” only started in the 1600’s. The idea is mentioned all the way back in the second chapter of the first book of the Bible: “A man shall leave his father and his mother, and be joined to his wife; and they shall become one flesh.”

That is an extremely Anglocentric TIL.

Also this bit, apparently written by accomplished historians if the author credentials are to be trusted, made me chuckle:

In mainland Europe in the Dark Ages (roughly 500 to 1000 A.D.), populations were so sparse, spread out, and loosely organized that last names were not necessarily needed to function in society.