I recently heard an interesting podcast on "memes" and the extent of their similarity to genes. One of the hosts (and many online commentators) had trouble with the idea that memes (units of information transmitted among humans) could replicate themselves - after all, a song or phrase doesn't copy itself, does it? This was contrasted with genes, which we were assured could self-replicate, and thus the meme idea was dismissed. We can choose whether or not to pass along a pithy phrase, so it doesn't have the status that a gene does.
Of course, to anyone who understands genetics, the idea that a gene "self-replicates" is pretty silly. Aside from a few special sequences of RNA (and damn if those aren't interesting) DNA is just a molecular encoding of information - not fundamentally that different from a long string of text. Genes are particular stretches of DNA that code for useful proteins, but they are still just information. It takes a bunch of molecular machinery inside a cell to copy that information (or, for that matter, to convert it in to a protein). While it's true that the individual enzymes that copy, transcribe, and translate the information are produced from genetic information, it takes a collection of genes working in concert to duplicate any of the individual genes. For the gene to become more common in the world, it has to be in an organism that survives and reproduces. Genes replicate, proliferate, and disappear in cells in organisms (even if those organisms are unicellular), and genes can't "do" anything on their own.
So why does everybody just assume genes are doing their thing replicating and proliferating? Well, the fact that Richard Dawkins's groundbreaking book was called "The Selfish Gene" may have something to do with it. Dawkins pointed out that from the point of view of a gene, an organism is a "survival machine." Genes don't really "care" about individual organisms beyond their ability to promulgate genes. To bolster this view, Dawkins (correctly) pointed out that individual organisms (and even species) are incredibly short-lived compared to genes; hemoglobin genes, for example, are something like 500 million years old, and the genes for enzymes like DNA polymerase are presumably as old as DNA-based life itself - which is the only kind we know (and yes, RNA viruses are still DNA-based; they require the use of plenty of proteins from their hosts' DNA to reproduce). Most folks seem to accept some sort of independent drive for genes since Dawkins published the book - hence the idea that they are "self-replicating" - and the way Dawkins pointed out that evolution was not just about the survival and reproduction of organisms was a big step forward in understanding. Nonetheless, the idea that emerged ("it's all about the genes") is just plain mistaken.
The problem here is that we humans are used to the idea of agency. That is, changes come from agents which are capable of action in the world. In human political and social systems, agency is a basic assumption; if something happens, somebody must have done it. It's a great concept for explaining a market or a legislature. In understanding an evolutionary process, however, agency is basically useless, because changes occur at so many levels (gene, organism, population) at the same time that one just can't ascribe evolution to a single agent. Genes don't evolve on their own; neither do organisms. Populations evolve (change genetically over time) only to the degree that individuals in the populations are more or less successful at surviving and reproducing, but the change is at a genetic level (usually described as a change in gene frequencies). So who is the agent?
Really thinking deeply about this is hard when you're raised on agency; hell, even evolutionary biologists use Darwin's term "natural selection," as if some agent ("Nature") was carefully deciding who deserves to survive. That, of course, is not just nonsense, but unnecessary; organisms just survive and reproduce, passing on genes that determine part of the likelihood of survival of those organisms. In that situation, there is no agent that has to "select"; instead, better-surviving libraries of genes emerge in the surviving organisms, period. Evolution is literally the most natural thing to happen to reproducing organisms with some sort of genetic system, no agent required.
Back to memes. We have information (words, phrases, ideas, music) that sits around on its own, but tends to get passed around when you have people talking to each other. We (people) use information, share it, find it helpful, tell our kids. Nobody has to go out and force us all to put "ROFL" in our social media posts, but it works, and it spreads. That's a meme, and it deserves the same sort of respect as a concept in social informatics that a gene does in biochemistry. OK, I made up the phrase "social informatics," but you get the point. Genes and memes spread, or they don't; one is biological evolution, the other social evolution, but in any case, there's no point to trying to find the Agent of Evolution behind it all. In a situation where genes or memes can be copied, it just happens.
