Dawkins points out that we can think of cultural items, memes, as parasites, too. Actually, they are more like a simple virus than a worm. Memes are supposed to be analogous to genes, the replicating entities of the cultural media, but they also have vehicles, or phenotypes; they are like not-so-naked genes. They are like viruses (Dawkins, 1993). Basically, a virus is just a string of nucleic acid with attitude--and a protein overcoat. A viroid is an even more naked gene. And similarly, a meme is an information-packet with attitude--with some phenotypic clothing that has differential effects in the world that thereby influence its chances of getting replicated. (What is a meme made of? It is made of information, which can be carried in any physical medium. More on this later.)

And in the domain of memes, the ultimate beneficiary, the beneficiary in terms of which the final cost-benefit calculations must apply is: the meme itself, not its carriers. This is not to be heard as a bold empirical claim, ruling out (for instance) the role of individual human agents in devising, appreciating and securing the spread and prolongation of cultural items. As I have already noted, the traditional perspective on cultural evolution handsomely explains many of the patterns to be observed. My proposal is rather that we adopt a perspective or point of view from which a wide variety of different empirical claims can be compared, including the traditional claims, and the evidence for them considered in a neutral setting, a setting that does not prejudge these hot-button questions.

In the analogy with the fluke, we are invited to consider a meme to be like a parasite which commandeers an organism for its own replicative benefit, but we should remember that such hitchhikers or symbionts can be classified into three fundamental categories:

parasites, whose presence lowers the fitness of their host;

commensals, whose presence is neutral (though, as the etymology reminds us, they "share the same table"); and

mutualists, whose presence enhances the fitness of both host and guest.

Since these varieties are arrayed along a continuum, the boundaries between them need not be too finely drawn; just where benefit drops to zero or turns to harm is not something to be directly measured by any practical test, though we can explore the consequences of these turning points in models.

We should expect memes to come in all three varieties, too. This means, for instance, that it is a mistake to assume that the "cultural selection" of a cultural trait is always "for cause"--always because of some perceived (or even misperceived) benefit it provides to the host. We can always ask if the hosts, the human agents that are the vectors, perceive some benefit and (for that reason, good or bad) assist in the preservation and replication of the cultural item in question, but we must be prepared to entertain the answer that they do not. In other words, we must consider as a real possibility the hypothesis that the human hosts are, individually or as a group, either oblivious to, or agnostic about, or even positively dead set against, some cultural item, which nevertheless is able to exploit its hosts as vectors.

The most familiar cases of cultural transmission and evolution--the cases that tend to be in the spotlight--are innovations that are obviously of some direct or indirect benefit to the genetic fitness of the host. A better fishhook catches more fish, feeds more bellies, makes for more surviving grandchildren, etc. The only difference between stronger arms and a better fishhook in the (imagined) calculation of impact on fitness is that the stronger arms might be passed on quite directly through the germ line, while the fishhook definitely must be culturally transmitted. (The stronger arms could be culturally transmitted as well. A tradition of body-building, for instance, could explain why there was very low [genetic] heritability for strong adult arms, and yet a very high rate of strong adult arms in a population.) But however it might be that strong arms or fishhooks are transmitted, they are typically supposed to be a good bargain from the perspective of genetic fitness. The bargain might, however, be myopic--only good in the short run. After all, even agriculture, in the long run, may be a dubious bargain if what you are taking as your summum bonum is Darwinian fitness (see Diamond, 1997, for fascinating reflections on the uncertain benefits of abandoning the hunter-gatherer lifestyle). What alternatives are there?

First, we need to note that in the short run (evolutionarily speaking--that is, from the perspective of a few centuries or even millennia) something might flourish in a culture independently of whether it was of actual benefit to genetic fitness, but strongly linked to whether it was of apparent benefit to genetic fitness. Even if you think that Darwinian fitness enhancement is the principle driving engine of cultural evolution, you have to posit some swifter, more immediate mechanism of retention and transmission. It's not hard to find one. We are genetically endowed with a biased quality space: some things feel good and some things don't. We tend to live by the rule: if it feels good, keep it. This rough and ready rule can be tricked, of course. The sweet tooth is a standard example. The explosion of cultural items--artifacts, practices, recipes, patterns of agriculture, trade routes--that depend quite directly on the exploitation of the sweet tooth has probably had a considerable net negative effect on human genetic fitness. Notice that explaining the emergence of these cultural items by citing their "apparent" benefit to genetic fitness does not in any way commit us to the claim that people think that they are enhancing their genetic fitness by acquiring and consuming sugar. The rationale is not theirs, but Mother Nature's. They just go with what they like.

Still, given what people innately like, they go on to figure out, ingeniously and often with impressive foresight, how to obtain what they like. This is still the traditional model of cultural evolution, with people husbanding their goods in order to maximize what they prefer--and getting their preferences quite directly from their genetic heritage. But this very process of rational calculation can lead to more interesting possibilities. As such an agent complicates her life, she will almost certainly acquire new preferences that are themselves culturally transmitted symbionts of one sort or another. Her sweet tooth may lead her to buy a cookbook, which inspires her to enroll in a culinary arts program, which turns out to be so poorly organized that she starts a student protest movement, in which she is so successful that she is invited to head an educational reform movement, for which a law degree would be a useful credential, and so on. Each new goal will have to bootstrap itself into the memosphere by exploiting some pre-established preference, but this recursive process, which can proceed at breakneck speed relative to the glacial pace of genetic evolution, can transform human agents indefinitely far away from their genetic beginnings. In an oft-quoted passage, E. O. Wilson claimed otherwise:

The genes hold culture on a leash. The leash is very long, but inevitably values will be constrained in accordance with their effects on the human gene pool. (Wilson, 1978, p167)

But Wilson's leash is indefinitely long and elastic. Consider the huge space of imaginable cultural entities, practices, values. Is there any point in that Vast space that is utterly unreachable? Not that I can see. The constraints Wilson speaks of can be so co-opted, exploited, and blunted in a recursive cascade of cultural products and meta-products that there may well be traversable paths to every point in that space of imaginable possibilities. I am suggesting, that is, that cultural possibility is less constrained than genetic possibility. We can articulate persuasive biological arguments to the effect that certain imaginable species are unlikely in the extreme--flying horses, unicorns, talking trees, carnivorous cows, spiders the size of whales--but neither Wilson nor anybody else to my knowledge has yet offered parallel grounds for believing that there are similar obstacles to trajectories in imaginable cultural design space. Many of these imaginable points in design space would no doubt be genetic cul-de-sacs, in the sense that any lineage of H. sapiens that ever occupied them would eventually go extinct as a result, but this dire prospect is no barrier to the evolution and adoption of such memes in the swift time of cultural history. [4] To combat Wilson's metaphor with one of my own: the genes provide not a leash but a launching pad, from which you can get almost anywhere, by one devious route or another. It is precisely in order to explain the patterns in cultural evolution that are not strongly constrained by genetic forces that we need the memetic approach.

The memes that proliferate will be the memes that replicate one way or another--by hook or by crook. Think of them as entering the brains of culture members, making phenotypic alterations thereupon, and then submitting themselves to the great selection tournament--not the Darwinian genetic fitness tournament (life is too short for that) but the Dawkinsian meme-fitness tournament. It is their fitness as memes that is on the line, not their host's genetic fitness. And the environments that embody the selective pressures that determine their fitness are composed in large measure of other memes.

Why do their hosts put up with this? Why should the overhead costs of establishing a whole new system of differential reproduction be borne by members of H. sapiens? Note that the question to be asked and answered here is parallel to the question we ask about any symbiont-host relationship: why do the hosts put up with it? And the short answer is that it is too costly to eradicate, but this just means that the benefits accruing to the machinery that is being exploited by the parasites are so great that keeping the machinery and tolerating the parasites (to the extent that they are tolerated) has so far been the best deal available. And whether or not in the long run (millions of years) this infestation will be viewed as mutualism or commensalism or parasitism, in the short run (the last few millennia) the results have been spectacular: the creation of a new biological type of entity: a person.