Some years ago I read Susan Blackmore's fine book, The Meme Machine, which was a breath of fresh air in an atmosphere where memes generally were being faddishly described as mind parasites that somehow corrupted their hosts and led us away from our true nature, whatever that might be. Blackmore, instead, provided a very thorough and thoughtful analysis of how the human brain might have evolved as an optimized host for memes, which gave us a significant reproductive advantage over our less quickly adaptable competitors. On this view, memes are as much symbiotes as they are parasites, because humans prosper most by absorbing and implementing useful memes like, for example, how to make and use tools or what kinds of berries not to eat.
A while ago, Dr. Blackmore wrote in The Guardian that she no longer believes religion is a virus of the mind, and I cringed, because I have spent a lot of time thinking about memetic taxonomy and to me, a virus is a very specific kind of parasite. As I've mentioned before, I consider chain letters to be the memetic equivalent of viruses. But it occurs to me that I've never explained here what other sorts of memetic organisms there are, so here goes.
Recall that a meme is to cultural evolution what a gene is to biology: the basic replicating unit. Genes influence the likelihood of their own replication in many ways, but generally speaking, a gene that produces traits that make its host likelier to survive and breed will tend to become more common over time than one that doesn't. Frequently clusters of genes travel together, because genes for sharp canine teeth tend to do better when accompanied by genes for the ability to digest meat, and so on, to use an example cited by Richard Dawkins (who invented the word "meme" in his 1974 book, The Selfish Gene.)
Now, biological organisms consist of physical bodies of amazingly complexity, and use an astonishingly diverse range of strategies to get the energy and raw materials they need to grow and reproduce. These strategies are shaped by genes, but not in isolation; there are countless other factors involved. Genes themselves only provide instructions on how to assemble specific proteins, and that only when plugged into the complex protein-assembling machinery of a functioning cell, which consists of much more than DNA and the protein molecules it generates. There are sugars and lipids and various ions and a whole lot of water involved, all of which must be in place for the machinery to function. Cells contain a host organelles that perform a variety of essential functions to keep the whole system running smoothly, and that's just at the cellular level; at the level of complex multicellular organisms like us, individual cells specialize in particular functions and organize themselves into tissues and organs and systems until you end up with a fish or a spruce tree or a cockroach, which you can spend your entire life studying without ever becoming aware of even the existence of genes. (There were, after all, biologists making important discoveries about living things long before Gregor Mendel worked out the theory of heritability, including Charles Freaking Darwin.)
You can see, then, why I characterize chain letters specifically as memetic viruses. There is some argument as to whether or not viruses should be considered alive, because they are not complete cells. They consist of a strand of DNA (or RNA) that encodes for some proteins, packaged up in an envelope made of some of those proteins, and that's about it. For a virus to replicate, it has to get inside a living cell where the DNA program can get plugged into the protein-assembling machinery. The life cycle is almost exactly analogous to that of a chain letter: a virus gets itself into the cell and instructs the cell to make more copies to send out to infect other cells, while a chain letter gets its instructions into your brain and tells you to make copies to send out to all your friends.
It's important to note, though, that a virus is not a gene and a gene is not a virus. Viruses are made of genes, but there's more to them than that. A viable virus must also include the protein coat that allows it to penetrate a cell, and the genes themselves can't just be any old genes; they need to provide for the replication of the virus itself. Otherwise all you have is a weird and short-lived way of mucking up a cell. (Actually, this can be turned to good therapeutic use; artificial retroviruses can insert new and helpful genes into your cells to cure genetic diseases, but never mind that.)
In the same way, a chain letter is not a meme, although it is primarily composed of memes. In the old days, snail mail chain letters also were made of paper and ink, an envelope with an address that delivered it to its target, and so on. Now they are generally just sequences of ones and zeroes that get converted into human-readable images, but the basic principle is the same: they are sets of instructions that explicitly instruct a host to copy them. And as not just any instruction counts as a chain letter, neither should every meme be considered a virus.
So what are the more complex memetic organisms out there? It gets a little complicated, because the analogies between memes and genes start to diverge when we move to the cell, tissue, organ and organism levels. Probaby a single human mind is the closest analog to a cell, but that gets confusing because you can have several distinct "organisms" sharing a single mind, whereas typically a single biological cell is thought of as being no more than one organism (not counting organelles with their own DNA like mitochondria and chloroplasts). I find it helpful to think of memetic organisms as "isms", more or less self-contained patterns of behaviour that develop out of a kernel of imitation.
For example, consider the ability to ride a bicycle, which I'll call here "bicyclism". If you can ride a bike, odds are you learned first by watching someone else ride a bike, and trying to imitate them. But you almost certainly didn't just hop on and start riding; it took time for you to develop the reflexes and attune your sense of balance to the new experience of operating a bicycle. Likely you fell down a lot during this process. So the bicyclism that currenty resides in your brain is not just stuff you learned by imitation; it's also stuff you had to practice and develop through trial and error on your own. And let's not forget that an actual, functioning bicyclism cannot exist without an actual physical bike to ride on!
Notice that there is a natural life cycle in the growth and replication of a bicyclism. First the memetic seed is planted: you observe and wish to imitate the practice of bike riding. Then there is the acquisition of the physical materials for the behaviour: you need to get a bike. Then there is growth and development: you practice and fall down and eventually figure it out. Finally, there is reproduction: someone else sees you ride by, and the process begins anew.
(Also notice that in the above example, there is no mention of language; you can learn to ride a bike just by watching and experimenting. But language can vastly speed up the process. Language is itself an exceptionally powerful memetic organism that facilitates the spread of memes by digitizing them for rapid transmission from brain to brain.)
Another thing to notice about this life cycle is the role of heritability. If you learned to ride a bike from someone who had a habit of always checking the cuffs of his trousers before starting out, you might inherit that habit. Across large populations of bicyclisms, one might be able to discern trends, family trees of who learned to ride from whom, by noting all the little stylistic quirks about just how one rides. (In fact, this is enormously complicated by the fact that unlike most biological cells, minds are exceptionally receptive to new memes, so we can keep on picking up new tricks or styles, confusing attempts at establishing a simple linear lineage.)
A bicyclism is, to my mind, an excellent example of a memetic organism. There is a bicyclism in my head, which is similar in many regards but still distinct from the bicyclism in your head; there is a population of bicyclisms consisting of all bicyclists. But bicyclisms are essentially single-celled creatures. Are there memetic analogs to multi-cellular entities?
Of course there are. Individual humans organize themselves into groups to perform various functions, and each of these multi-human groups can probably be characterized as some kind of memetic organism insofar as they replicate by a memetic process in which each member of the group holds a copy of the "memome". A church, a company, a family, a club, a military unit; all of these involve varying degrees of specialization by the members, all of whom at least initially learn part of their roles in the organization through imitation and then develop their skills further through practice. Some organisms involve very little differentiation among the members, while others can become highly hierarchical and specialized.
Consider a religion like Catholicism, for example. It replicates a doctrine (a behaviour of thought) from mind to mind initially by a kind of imitation, a transmission of ideas through language, ritual and artifacts. This isn't merely memetic, though; it is not just a matter of passively receiving what one is told, because most people tend to think about it a little at least, to try to understand what is meant, whether or not they entertain any actual doubts. The process of interpretation is not itself memetic; one has to practice thinking about something in a certain way before one becomes adept at it, that is, before one becomes a strong believer in it.
Yet the Catholic Church itself is not simply the set of people who have a particular set of beliefs called Catholic. It is an actual organization, with a hierarchy headed by the Pope, and into which individual Catholics are integrated as clergy and lay members of this or that diocese. And the Catholic Church can be said to have offspring of its own, so to speak, in the Anglican and Protestant and various other denominational churches that have split off from it over the years. And it has siblings (Eastern Orthodox? The Coptic Church?) and cousins (Islam) and at least one parent (Judaism, and maybe Mithriasm?) and connections to Zoroastrianism and so on.
I don't want to delve too deeply into the history of the Abrahamic religions here. Rather, I just wanted to illustrate some of the ways in which the analogy of memes to genes can more fruitfully be expanded beyond the dead end of memes=viruses. Memes aren't viruses or parasites; they are the genes of cultural evolution, components of everything from chain letters to technology to philosophy to religion.