The opening of an excellent piece by Christopher Mims at Quartz which explains the science of measuring the life spans of memes:

“More and more of the things that set the internet on fire are of that species of charmingly moronic pairing of text and image that allows even the post-literate to feel like they have partaken of a shared cultural moment. And now, scientists are beginning to understand how the curiously addictive visual tropes known as ‘memes’ are born, why they die, and whether or not it’s possible to predict which will ‘go viral’ and be harvested by the night-soil merchants up at meme warehouses like Cheezburger.

Treating memes like genes tells us which are likely to spread

The internet, of course, was barely in its infancy when Richard Dawkins, a British evolutionary biologist, coined the term ‘meme’ back in 1976. And he meant it as a much more nuanced concept, encompassing pretty much any idea that is good at propagating from one human brain to another—whether it is dialectical materialism or the tune to Happy Birthday.

But Dawkins was deliberate in his comparison of memes to genes. Like the molecular units of inheritance, memes ‘reproduce’ by leaping from one mind to another, ‘mutate’ as they are re-interpreted by new humans, and can spread through a population. The internet has radically accelerated the spread of memes of all kinds; but it has also led to the rise of a specific kind of meme, the kind encapsulated by a phrase or a picture. And importantly for scientists, the life of a such a meme is highly measurable.”