Last night, my Twitter timeline was filled with sad reflections on the life of Nigerian author Chinua Achebe, who had passed away.

Another legend and elder has passed. http://t.co/Q33qNQhpux

— Lisa Kwong (@poetambassador) March 22, 2015

Chinua Achebe, Nigerian Writer, Dies at 82 http://t.co/tPRR316QHy

— Julian Gallo (@JulianGallo66) March 22, 2015

A world now without Chinua Achebe: http://t.co/Hf8eUn3XZh

— Jaimie Gregory (@jaimie_gregory) March 23, 2015

So twitter reports tha Chinua Achebe has passed on…RIP

— Mellow (@IAreMelloW) March 23, 2015

Bugger! Another one gone. Achebe http://t.co/mloESHvJm2

— devangshudatta (@devangshudatta) March 23, 2015

So sad … #ChinuaAchebe, Nigerian #writer, author of "Things Fall Apart" — Dies at 82 http://t.co/6vO6X2aKB8 #News pic.twitter.com/MJfVvVKzSI

— RGF3 Esq. (@Iron_Light) March 23, 2015

A gracious man and great writer passes away. He will be missed. Chinua Achebe, Nigerian Writer, Dies at 82 http://t.co/4LwS2ikUm5

— Lesley Krueger (@LesleyKrueger) March 23, 2015

A titan of literature + perpetuator of understanding, Chinua Achebe, died yesterday. We owe you so much http://t.co/64Qwhm4XQn.

— Shira Schindel (@Shiras24) March 23, 2015

Very sad — but the sadness is cut by the fact that Achebe actually died two years ago. Those tweets are linking to a New York Times obit from 2013. Call it a Reverse Vigoda.

The list of people fooled included some high-ranking officials; it made the front page of Hacker News, and others had some fun with it:

Looks like @AmbassadorRice has deleted this Chinua Achebe tweet pic.twitter.com/QgDcZiMJQw (via @dadakim)

— Ben Nwomeh MD (@bnwomeh) March 23, 2015

This just in to Weekend Update. Nigerian author Chinua Achebe is still dead. http://t.co/SNzgHNwrB0 pic.twitter.com/MQBztIFnnr

— Michael Kirkpatrick (@OtimMichael) March 23, 2015

Why did a two-year-old obituary get shared as news? I spent a few minutes trying to find the story’s Patient Zero, without much success; several of the early key tweets have been deleted. (My first spotting of it was this Jesse Sheidlower tweet, which I suspect played a role in its spread through Media Twitter.)

It doesn’t seem like there was any crass viral hoax going on here. My best guess is a few people tweeted remembrances for the two-year anniversary of his death, a few people mistook those for fresh news, and off it went.

But no matter its precise origin, this stream of surprised R.I.P. tweets — they’re still coming, at this writing — tells us a couple of things about social media.

— Social media is, in some important way, unstuck in time. You know how Facebook sometimes resurrects old news stories and sends a gazillion readers their way? Or how some publishers intentionally repost months-old stories, sometimes completely un-updated, hoping for a new round of social lift?

There’s something fundamental about the shift to digital that lets old material seem timely. Print newspapers and TV news broadcasts are, in some core way, telling you: Here’s what’s happened since the last time we produced one of these things. The stream metaphor of Twitter and Facebook drops the illusion of chronology — old links end up alongside new ones, and its relentless flow makes it inevitable that we’ll miss things along the way. If you see a half-dozen tweets in your stream saying something is true (and new), it’s less likely you’ll do due diligence.

— Social media is performative. This isn’t news to anyone, but social media is a platform for people to put forward an image of themselves. Tweeting about the death of Chinua Achebe makes it clear that you (a) know who Chinua Achebe is and (b) that you care enough to mark his passing. And the death of someone prominent is classic of-the-moment news — the kind of thing that you might want to share quickly without even clicking the link. This piece from the Indian site Firstpost gets at some of the layers nicely, noting that on social media “all of us are guilty of the crime of reflex sharing: see — react — share.”

Our reaction to any big news event is public. We all rush to have a view, especially so when tragedy strikes. All the better if a public figure is involved. We all want to get in on the grief parade. Show the world that we are in tune with current events, and that every significant event has an impact on our lives too…

We’re pretty sure that a lot of the people who shared the NYT link and beat their social media chests with grief today had most likely done the same two years ago when he really passed away — and just forgotten about it. In the endless river of RIPs, it is easy to lose track those you have so loudly mourned on your TL. And while a section of people who did remember that Achebe had died two years ago may snigger at their timelines in superior fashion, the truth is that this phenomenon says something about all of us and the way we are evolving to respond to the constant flow of information that comes to us via the Internet.

Given the speed at which we acquire information, we often have very little time to parse through it all. So more often than not, we use social media as a filter. If our friends post something, we are more likely to believe it to be true. But then we feel the need to react to it as well, whether or not it is relevant to us or not.