A screenshot from a Harlem Shake video made in February 2013. You know, when people were still jazzed about it. (YouTube/via Wikipedia)

Roughly every minute and 43 seconds, someone uploads a Harlem Shake video to YouTube.

Yes, we’re talking about that Harlem Shake — the year-and-a-half-old dance video craze, wherein a group of people get down to Baauer’s “Harlem Shake” in spectacularly silly fashion. By all accounts, most of the Internet forgot about the meme shortly after it went viral, in March 2013. And yet, a full 20 months later — untold eons, in Internet time — dozens of YouTube users continue to quietly upload their long-belated versions to the less-trafficked corners of site, often appending a “this is late” by means of apology. Per YouTube, and as of this writing, users have uploaded roughly 6,000 videos that match the search term “Harlem Shake” within the past week — which averages out to a little more than one video every two minutes.

That makes for funny trivia, in and of itself — funny enough that, when the technologist Andy Baio noticed it last Thursday, he promptly tweeted it out as a “PSA” to his 27,000 followers. But the tenacity of the Harlem Shake is more than just good fun: It’s a lesson in the surprisingly long lifecycle of an Internet meme. As the Belgian researcher Klaas Chielens put it in 2006, “a meme is virtually immortal.”

That seems odd, when you’re talking about something as fleeting as a cute cat or a one-off YouTube trend. But Chielens, and others like him, aren’t drawing on the very modern definition of Internet meme — they’re talking memetics, the study of how cultural ideas and motifs spread. It looks a lot like evolutionary biology.

Pretend, for a minute, that the Harlem Shake is not a stupid video you hated in 2013, but a species in a very competitive ecosystem — The Internet. Like other species, the Harlem Shake needs to reproduce to survive. Otherwise it goes the way of the dodo. Womp womp.

The basic lifecycle of a meme. (Bjarneskans et al)

So the Harlem Shake does reproduce, albeit in a manner far more PG than whatever you studied in 9th-grade biology. First it’s transmitted: one person makes a Harlem Shake video. Then it’s decoded: someone else receives the video, watches it, and either “gets” it or does not. At that point, the recipient can choose to make her own Harlem Shake video, or forward her friend’s, or forget the whole thing entirely — maybe in favor of another cooler, buzzier meme. This is called “infection,” a bit of epidemiology lingo that, like “viral,” has made it into common web parlance. It’s how memes on a competitive Internet survive or die.

Of course, as in other competitive ecosystems, not all Internet species are equally equipped to survive. You have your dinosaurs. Your short-lived passenger pigeons. Your sturgeons and lampreys and horseshoe crabs that have somehow been kicking around for millennia. In the case of Internet memes, the ones most likely to survive are those that make their host, i.e. the person Facebook-posting them, look the most cool, funny or in-the-know. They’re also the ones that are the easiest to understand, to copy and to communicate to other people.

The Harlem Shake is so sublimely perfect, in this regard, because it literally requires only a group of pals and a camera phone: You don’t even need to learn a dance to do the Harlem Shake. You don’t even need to know how to take video, really! And the appeal of the meme is immediate and easily understood: It’s pure, wordless, euphoric silliness, of a sort recognizable to people all over the world.

Of course, memes — cultural ideas — aren’t always so simple. Christianity is considered one of history’s most successful memes, and it relies on an entire complex of symbiotic ideas and beliefs to get its point across. The opening to Beethoven’s Symphony No. 5 in C minor is also a meme, a simple eight-note motif that has been reproduced so frequently in popular culture that it remains immediately recognizable, 200 years later.

“Serious” people will surely scoff at the gulf between Beethoven and the Harlem Shake. But whatever their perceived value or high/lowbrow origins, both phenomena follow the same lifecycle. Transmission, decoding, infection, coding: They live and die the exact same way. If anything, that should muffle the haters who see Grumpy Cat or Alex from Target as some kind of curse on the culture; even our most vapid Internet memes, it turns out, are scaled models of a process that rules every aspect of our intellectual and cultural experience. Even a casual tweet about the longevity of the Harlem Shake is essentially a discourse on the the spread and survival of ideas.

I asked Baio, the man who kicked off this particular discourse, what he made of the whole thing: Was he surprised by the dozens of new Harlem Shake videos that appear every hour? Did he attribute its success to anything particularly?

“Inevitably, memes propagate through different regions and subcultures at different rates,” he wrote. “It will always be new to someone.”

And as long as that’s true, the Harlem Shake will live to meme another day.