1 EEB210 Spring 2008 Lecture #23: Memesis and evolution of culture Culture: refers to differences in behaviors between various subgroups within a species where these differences are due to social learning (cultural transmission) rather than genetic differences Two examples of cultural transmission in animals: a. dialects in bird song---different breeding populations within a species sometimes have slightly different songs and these songs are learned by young male birds as they listen to the songs of their fathers b. washing of food by a population of Japanese macaques (monkeys)---this one has been widely cited, but may not involve learning by imitation Can a Darwinian approach add anything to our understanding of culture and particularly to an understanding of the role of culture in shaping human evolution? One interesting approach began with Richard Dawkins’ suggestion of the term “memes” to denote units of culture that are passed from person-to-person to become incorporated into our culture. For example, the Star Spangled Banner was the idea of Frances Scott Keyes and it has been passed between individuals ever since so that now we all know it. In Dawkins’ view, the idea of the Star Spangled Banner resides in all our minds, with all its associations. Other songs have been written and promptly forgotten. (While we are on the topic of music, Daniel Dennett, one of those who has written about the theory of memes, used the following example to illustrate how hard it is to eradicate a good (popular) meme once it is established in our minds: We are all very familiar with the music of Edward Elgar since it is played ad nauseum at every graduation ceremony. Gilbert and Sullivan wrote a piece in “The Mikado” that would be a wonderful alternative to relieve the boredom at graduations, but it will never be used. That is because we simply can’t hear the melody without associating it with “The Lord High Executioner”.) There is some parallel between the way memes, or items of culture, are passed from individual to individual and the way genes are replicated and passes from parents to offspring. The concept of memes has been further developed by Susan Blackmore, Daniel Dennett, and others. In the field of “Memeology” (also called “Memetics”), memes are treated as replicators much as genes are treated as the replicators of biological evolution. (This may seem strange, but consider that early evolutionary biologists developed much of the theory that has lasted to the present day even though they had no idea what the basis of inheritance---i.e., the replicators---were.) At this point, we should review a part of Darwin’s theory in a somewhat different and more up-to-date way. Basically, the Darwinian view, as embellished during the last 2 century, suggests that only the following requirements must be met in order for evolution to occur: 1) the existence of replicators, or units that can reproduce themselves, 2) variation---the replicators must replicate themselves fairly accurately (otherwise things will become very random), but there must be occasional mistakes or inaccuracies (mutations) in replication (otherwise no new opportunities for change will be created---e.g., no evolution), 3) selection---some sort of factors in the environment that can cause certain versions of the replicators to be favored over others Indeed, it has been suggested that when these 3 conditions are met, then evolution must occur. Daniel Dennett has referred to the process of involving these 3 steps as the evolutionary algorithm. Genes clearly satisfy the first two requirements, and there is plenty of evidence that many environmental factors result in some genes being favored over others. What about memes---units of culture? There is a clear link between memes and our ability to learn by imitating others, a talent that seems far more developed in humans than for any other species, and which may be the major key to our “intelligence”. There are a number of differences in the way memes are spread as compared to genes, and two differences that are especially important are: a. memes can spread through human populations far more rapidly than genes can spread b. memes can be ‘transmitted’ to non-kin as well as to kin (horizontal vs. vertical transmission) c. gene duplication is an important, but relatively rare event---with the exception of gene duplication events, there are a limited number of genes for each individual; therefore, any new gene must replace a gene that was formerly present in the genome (2 loci for each set of alleles---one locus on each of the paired chromosomes---and a set total number of loci for the entire genome)--it is not obvious what the limitation is on number of memes; in any event, it does not seem that an old meme needs to be lost to make way for a new one Coevolution: Consider flowering plants and their insect pollinators. In this case, the evolution of an insect species is influenced by the evolution of the plant species that is pollinated by the insect, and vice versa. Blackmore discusses coevolution with respect to interactions between genetic and memetic evolution in humans. 3 There are interactions between memetic evolution and genetic evolution, but because of “a” (above) genetic evolution often cannot ‘keep up’ with memetic evolution. Also, since memes can be very effectively transmitted to non-kin, certain memes may be able to spread very effectively even if they have negative consequences for the transmission of genes. Who benefits from genetic evolution? The genes Who benefits from memetic evolution? The memes Important insights about cultural, as compared to genetic, evolution: a. importance of imitation learning for cultural evolution b. genes transmitted at rates related to generation time; memes can be transmitted much faster c. ‘lateral’ transmission of memes vs. ‘vertical’ transmission of genes A major question is: Why are some memes much more successful (i.e., transmitted much more readily) than others? 4 Additional considerations on memetic vs. genetic evolution: Consider a (hypothetical) meme that promotes marriage and reproduction between siblings. Would such a meme be likely to be severely checked with respect to its propagation because its negative effects are confined to close kin? Would that depend on whether the meme can spread only vertically or both vertically and laterally? Would it be unlikely that such a meme would ever become popular, in view of our evolved tendency to avoid incest? Effects of ‘copying errors’ on genes vs. memes---most mutant genes are unsuccessful, but variations in memes are probably much more likely to be successful---also, a mutation to a gene is a random process with no relation to the rest of the genome---but changes in memes and appearance of entirely new memes are not always ‘random’ in this sense--that is, the vehicle (human) can change the meme in ways that are likely influenced in a ‘systematic’ way by the other memes present, but the vehicle cannot change a gene---a discussion of recent advances in genetic engineering might be interesting at this point The requirement for rapid replication (i.e., fecundity) is largely a relative requirement; that is, in genetic evolution, an allele must ‘out-compete’ other alleles at a given locus to spread through the population---similarly, fecundity requirements for success in memetic evolution is relative, but only in the sense that memes must out-compete memes with which they are in direct competition; for example, one religious idea may be in direct conflict with alternative religious ideal (for example, when Catholicism and various Protestant sects were in direct competition) Is memetic evolution Lamarckian? It is in a very rough sense in that memes acquired during the lifetime of the parent may be passed on to offspring. However, note that Lamarck accepted the concept that inheritance was strictly ‘vertical’, just as in the later (and correct) version of genetic inheritance. Thus, Lamarckism does not include the idea of lateral ‘inheritance as in the case of memetic evolution.