Why is it that the maiden name is traditionally dropped when a woman is getting married?

Why is it that the maiden name is traditionally dropped when a woman is getting married? Is this something that predates back many civilizations ago? Or is this a relatively newfound trend?

Inheritable family names may be considered a relatively new trend, only dating back to the dawn of the Renaissance in Europe, that is, their use on a large scale (say, 1500s). In some parts of Europe, they only were forced on the populace in the 1800s, or the 1920s, and Iceland still doesn't use them. On the other hand, in Asia they date back for thousands of years in some cases, like China, and still aren't used yet, as in Myanmar.

This is entirely a cultural trend, and each little culture group works it out for themselves. It isn't religious, or it would be largely the same throughout Christendom, and it wasn't. The Spanish notably didn't.

The Italians in the 1500's didn't. Negri's lists of participants in Nuove Inventioni di Balli lets us see that single women are known by personal name or two and family name (Antonia Viale) but married women by that plus "and" and the husband's family name in feminine form: Anna Sfondrata & Visconte is one of the Sfondrati who married a Visconte, while Anna Visconte & Arconata is a Visconte who married one of the Arconati. Lucia Visconte & Visconte was a Visconte who married a cousin.

So changing the maiden name to the husband's family name is not only relatively recent (depending on getting family names) but a minority habit. It's a cultural choice. Some, like the Italians or the Chinese append Mrs. Hisname like a title. Others, like the English and the Japanese, change the name of the woman.

Unless, of course, they change the name of the man. In Japan, it was pretty normal that a man with just daughters would adopt her husband so the children would continue his family line, even if, technically, this made the happy couple brother and sister. They knew what was going on, and ignored that level of technicality.

In other cases, in England husbands would be convinced, usually by financial incentive, to append the wife's father's name to theirs, which is how you got hyphenated names. Not that they always used hyphens. Lord Byron was born George Gordon Byron, 6th Baron Byron, but later became George Gordon Noel, 6th Baron Byron, as taking the name Noel was the requirement to inherit a bunch of money from his wife's mother, whose maiden name it was.

LSS: It's only used by some cultures, especially the Anglophone, not by most. It is a Modern habit in Europe, and is disappearing on the legal front, though the whole Mrs. business is often retained socially.

SOURCE: Ingraham, People's Names, McFarland, 1997

[Note: I took the thrust of the original question to be about the origin of patrilineal naming conventions, but that is a step removed from what is actually asked. I leave the answer anyway, as I don't feel it is entirely without merit.]

Since you ask the "why", it's worth pointing out that, similar to the wheat and chessboard problem, if neither partner dropped their name, then after fewer than 30 generations it would be impossible for a person to state their full name even once, even if they made it their life's work. 30 generations is about 600-700 years, which is, coincidentally, roughly as long as surnames have been common in Britain. It would only take 10 generations or so for a name to take over an hour to recite.

To avoid this, one or both partners must necessarily reduce the complexity of their own name if they are to incorporate a component of their partner's name, and still produce a heritable surname. Even in cultures that ostensibly keep both names, there must be some trimming of older or less significant ancestors. For example, although Spanish convention retains both surnames, the two grand-maternal surnames are discarded in the following generation, and the maternal grandfather's surname is lost the generation after that.

This leaves only the question of which name to cull and, with some notable exceptions aside, this follows the wider societal pattern.

(I assume this question relates to the traditions of Great Britain and its former colonies such as the Canada, Australia, New Zealand and the United States.)

The woman does not "drop" her maiden name. If she is a Christian or a Jew, she assumes the name of her husband because in both beliefs the act of marriage joins the two inseparably as one. By ancient law, such as the old Scottish Civil Law, the maiden name is subsumed by name of the house, which is normally the name of the man who owns the house, but in theory BOTH the name of the man and the woman could change, if by the marriage a new house were created. Under old (non-Christian) English law, children and wives and any other dependents assume the name of man because he possesses them and also because he takes responsibility for their actions. For example, if Mistress Neville commits a crime than it is Lord Neville that will be held accountable. Thus, the name creates a legal obligation.

[Laws Relating to Wives] When a Woman marries, she gives her self over, what she brings with her, to her H U S B A N D's Power. She parts with her very Surname, and assumes her Husbands. If she has any Tenure, it is all in Capite, that is, she holds it of, and by her Husband, who is the Head of his Wife. She can make no Contract, nor give away, or alienate any Thing, without her Husband's Consent. In short, a marry'd Woman can call nothing her own, unless it be otherwise settled before Marriage.

- The Present State of Great Britain and Ireland by Guy Miege (1715)

Note also that under English common law only a legal wife can attain the name of man, so a concubine (a woman without license from bishop) by law has to keep her maiden name. Therefore, in the old days, if a woman had a different name than her husband then it was assumed she was a concubine, not legally married. Since most married women did not want to be mistaken for a concubine, they customarily were rigorous in using their husband's name.