Gangnam style, Lolcats, and Chuck Norris’ superhuman feats are all memes – units of cultural transmission – that spread through the internet. But when the term was originally coined, memes were posited as vehicles of a kind of evolution, similar to genes and biological evolution. So are the memes that colonize our brains simply those that survive natural selection? Don’t we get any say in the viruses that populate our minds? What happens if the fittest memes are also the most detrimental to us? John and Ken explore the mutations in their minds with Susan Blackmore from the University of Plymouth, author of The Meme Machine.