Since when are we all on a first-name basis?

Time was, if you had to line a bunch of people up alphabetically, you did it by surname:

• Ball, Lucille
• Marx, Harpo
• Zoolander, Derek

More and more, though, we seem to be arranging people by first name

• Derek Zoolander
• Harpo Marx
• Lucille Ball

Seems odd.  I blame the web.  Gmail does it.  Facebook does it.   Wikipedia can generally autocomplete from a first name ("Ab" gets me Abraham Lincoln at the top) but not the last (spelling out "Lincoln" in full gets me Lincolnshire and a longish list of other names, but nothing on the president).  There are plenty of other examples, I claim.  Indeed, it almost seems to be becoming the norm.

Objectively, there's probably not much to pick between the two schemes.  Without actually measuring, I'd guess that last names tend to be more unique (or "more nearly unique", if you must), but on the other hand we tend to think of people with their first names, well ... first.

Now perhaps this is just a generational thing.  Kids These Days, after all, have no regard for propriety and convention, just like my generation before them.  Perhaps the major software companies have had a hand, spreading their Silicon Valley disregard for regimented old-school thinking.

However, I think Wikipedia's autocomplete is notable.  If we're searching for something about someone, the key to our search is the person's name, as we would say it.  I don't think "What was Marx, Harpo's birth name?" (Adolph, changed to Arthur by 1911).  I think "What was Harpo Marx's birth name?" or just "What was Harpo's birth name?" (or I could just honk and whistle).  Either way, I start with "Harpo", and sure enough, "Harpo Marx" is on the list by the time I've typed that.  Other systems work similarly.

Searching by typing something in and expecting results to come back is quintessentially webby, and the autocomplete box is Web 2.0 in particular (whatever Web 2.0 is).