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Transcript
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.