Why do things go viral, and should we care? … In an age where politicians campaign through social media and viral marketers ponder the appeal of sneezing baby pandas, memes are more important than ever—however trivial they may seem. … But trawling the Internet, I found a strange paradox: While memes were everywhere, serious meme theory was almost nowhere. Richard Dawkins, the famous evolutionary biologist who coined the word “meme” in his classic 1976 book, The Selfish Gene, seemed bent on disowning the Internet variety, calling it a “hijacking” of the original term. The peer-reviewed Journal of Memetics folded in 2005. “The term has moved away from its theoretical beginnings, and a lot of people don’t know or care about its theoretical use,” philosopher and meme theorist Daniel Dennett told me. What has happened to the idea of the meme, and what does that evolution reveal about its usefulness as a concept? … Dawkins explained, genes could not account for all of human behavior, particularly the evolution of cultures. So he identified a second replicator, a “unit of cultural transmission” that he believed was “leaping from brain to brain” through imitation. He named these units “memes,” an adaption of the Greek word mimene, “to imitate.” … Dawkins’ memes include everything from ideas, songs, and religious ideals to pottery fads. Like genes, memes mutate and evolve, competing for a limited resource—namely, our attention. Memes are, in Dawkins’ view, viruses of the mind—infectious.