Laor and Jablonka devote much of their review of Mesoudi's "Cultural Evolution" book
to a call for development and systems theory. Many of their points read like criticisms of memetics.
While I have some differences from Mesoudi, compared to Laor and Jablonka, Mesoudi and I are very much
singing from the same hymn sheet. So, a few replies. Laor and Jablonka ask?
Like cultural behaviors, institutions such as hospitals or churches, are not included in Mesoudi'sdefinition of culture. He suggests that they, like behaviors, are the “phenotypes” of a “cultural genotype” stored in people's brains as neural networks (for example, 3, 213). But since the neural network is a product of social learning that occurs during human development, in what sense is it a genotype? Are “phenotypes” and “genotypes” embodied within an individual or distributed among members of a collective? It seems to us that adherence to notions of genotype and phenotype in the cultural realm, where heredity is an aspect of development and requires an active process of reconstruction, is misplaced (it is, in fact, in need of qualification even in the biological realm!).
There's a neat resolution of this issue: genotypes are composed of heritable information, phenotypes are the things that are influenced by them. This idea applies equally to DNA genes and to memes. The concepts often imply the notion of an individual - and so we have to say what a cultural individual is - but that isn't an insurmountable problem.
As Mesoudi confesses, his outline of a cultural-evolution synthesis inherits the problems of the twentieth century MS, in that it lacks a developmental perspective. We agree with Mesoudi that what development means in the cultural multi-generational context is not entirely clear. However, Jablonka and Lamb have argued that this lack of clarity is part of the solution, not the problem: it is inherent in the fact that the notions of heredity and development in the cultural realm are far less distinct than they are in the biological case.
Genetics and memetics don't involve the study of development. Development is treated by these theories as a black box - containing
arbitrary transformations which map from genotypes to phenotypes. Certainly development influences evolutionary trajectories. However, meteorite strikes, earthquakes, and fashion also influence evolutionary trajectories - we can't include everything under the umbrella of evolutionary theory. Development is a pretty different subject. Yes, there's evolutionary ontology, which applies evolutionary concepts to development - but it is OK to study development separately. As for the supposed "lack of clarity", the concept of "development" is best taken to refer to mappings from genotypes to phenotypes. It applies equally well to the organic and cultural realms. Maybe there's disagreement about the topic, but it seems easy enough to make it into a clear concept.
We believe that the major difference between the approach promoted by Mesoudi and that adopted by most social scientists is that the latter treat culture as a system. Cultural systems are not super-organisms, but they are also not an assembly of individuals, institutions and traits. They are – to differing extents and in different levels and ways – functionally integrated entities, and they occupy a middle-ground between a super-organism and an aggregate, a locus that is difficult to conceptualize if one is wedded to a traditional population-genetics-based metaphor. Social scientists endorsing the systems view do not reject approaches that focus on distinct and isolatable elements of culture, but they do treat the results of such analyses with caution, regarding them as limited and preliminary forays into the analysis of culture.
There are two issues here. The first is that cultures are, overwhelmingly, assemblies of individuals, institutions and traits. Analysis of culture in those terms is highly productive. Entire cultures don't have intelligent designers making them. They are cobbled together by cultural evolution. Analysing culture in terms of its parts follows the scientific practice of reductionism, of breaking down a complex whole into its component parts in order to understand it. This has been a tremendously productive approach in practically all branches of science. However, the application of frequency analysis - and other such techniques - to cultural variation doesn't presuppose the lack of high-level system characters. Their existence, or rather in most cases their lack of existence, is a separate empirical issue.
Cultural traits have long been used in anthropology as units of transmission that ostensibly reflect behavioural characteristics of the individuals or groups exhibiting the traits. After they are transmitted, cultural traits serve as units of replication in that they can be modified as part of an individual's cultural repertoire through processes such as recombination, loss or partial alteration within an individual's mind. Cultural traits are analogous to genes in that organisms replicate them, but they are also replicators in their own right. No one has ever seen a unit of transmission, either behavioural or genetic, although we can observe the effects of transmission.
"Cultural traits are analogous to genes"?
That muddles together the phenotype and genotype!
A cake isn't analogous to a gene, since it is the recipe that makes it that is normally copied from.
It's memes that are most like genes, not the traits that they code for.
Traits can sometimes behave a little like genes if there's only a trivial developmental process involved in their production. If developmental processes become more complex, traits become a lot less like genes and a lot more like bodies.
I'm pretty sure that - if more people adopted the memetics terminology, we could avoid this kind of muddle.
Samuel starts out by calling the idea "completely wrong" in the organic realm - which seems a bit strong.
The answer Samuel gives for the cultural realm is that it's not always wrong in the case of cultural evolution - saying that "cultural ontogeny recapitulates phylogeny".
However, unfortunately, it turns out that Samuel isn't talking about cultural development processes at all! An example of a cultural development process would be where a recipe turns into a cake - i.e. memes turn into meme products. Instead, Samuel is talking about the process of acculturation - the way in which humans acquire memes during their own developmental process. Describing this process as being analogous to ontogeny in cultural evolution seems to be pretty misleading to me. That's the ontogeny associated with the human genome going on there - not a form of cultural ontogeny! I don't think that Samuel means what he says...
Mesoudi doesn't make this mistake in the original article. Instead he says:
Individual ontogeny recapitulates cultural history for mathematical knowledge: children learn mathematical concepts in the same order that they were first invented historically.
That seems fine to me - he's talking about an individual human child. Though as an aside we do see computer programming before calculus these days.
Does ontogeny recapitulate phylogeny in the cultural realm? Probably less so than in the organic realm. The reason ontogeny recapitulates phylogeny at all is because developmental processes build on top of prototypes without going back to refactor them out of existence. There's also layering processes in development. So, for example, the "reptilian" brain appears in mammal embryos before the neocortex does - a case of ontogeny recapitulating phylogeny. The same kind of thing happens in the cultural realm - occasionally - and it's probably a universal evolutionary process. A skyscraper starts out looking a bit like a house (which was invented first) - because it is like a house with more layers added on top. However, ontogeny probably recapitulates phylogeny less frequently in the cultural realm - because engineers are so often involved there - and they are often better than natural selection at refactoring - and eliminating the sort of signs of phylogenetic history that residual prototypes and developmental layering often depend on.
Hi, I'm Tim Tyler, and this is a review of this book: Cultural evolution by Alex Mesoudi.
This is a great book about the important topic of cultural evolution.
Alex Mesoudi is an experimental psychologist working in the field, and has previously published numerous papers and a PhD thesis on the topic.
His book lays out the case for a Darwinian theory of cultural evolution in plain language, in a manner which should be comprehensible to a wide audience.
The preface states his aim with the book - which he says "is to nudge the social sciences along a little". He does this by illustrating the progress that has been made in explaining culture scientifically using Darwinian evolutionary theory.
The book is divided up into introductory material, microevolution, macroevolution, experimental work, field work, evolutionary economics, culture in non-human animals and a chapter about the coming evolutionary synthesis for the social sciences.
The writing is dense, clear and polished. The first three chapters are great - so best to start at the beginning. Much of the second half of the book consists of summarising literature in the field, which Mesoudi does pretty well.
The book does a good job of making its case. Most readers will probably come away convinced that the vast majority of Mesoudi's ideas on the topic are correct.
The book has several themes. One is that cultural evolution is Darwinian. Another is that cultural evolution is not neoDarwinian. That is true, but it probably goes for organic evolution as well.
Mesoudi proposes that we need a Darwinian synthesis for the social sciences - mirroring the neoDarwinian synthesis that took place in the natural sciences in the 1930s and the 1940s. That is true - we do need something a lot like that.
At this stage, it is time for some objections:
The neoDarwinian synthesis that took place in the natural sciences left out symbiosis. The cultural Darwinian synthesis that Mesoudi proposes also apparently leaves out symbiosis. Mesoudi's whole book has no mention of mutualism, parasitism, epidemiology or immunology in a cultural context. This is surely a big mistake. Cultural evolution is dominated by the phenomenon of symbiosis. The models on which modern strains of cultural evolution are based were originally drawn from epidemiology. Mirroring the sutuation in the 1940s, we do have a pioneering theory of cultural symbiosis - due partly to Cloak (1975) which was popularised by Dawkins (1976). However, Mesoudi dismisses this work as being a "fad". Back in the 1940s the neoDarwinian synthesis had an excuse for leaving out symbiosis - because it was very poorly understood at that stage. Now, symbiosis is still poorly understood, but we know at least enough about it to know that we can't leave it out.
On a possibly-related point, Mesoudi's account of culture is incredibly positive. Mesoudi gives an argument for culture being adaptive, and barely mentions any other possibility. After a while I was on the lookout for any mentions at all of cultural traits that were deleterious to their hosts. In the whole book, I found: celibate priests, the small family size norm and suicide bombers. So: some deleterious cultural traits are mentioned - but that is an astoundingly-short list for a 264-page book on this topic. Perhaps Mesoudi's lack of treatment of cultural parasitology and immunology arises partly from an under-appreciation of the significance of deleterious cultural traits. As the obesity and smoking epidemics illustrate, deleterious cultural traits are actually commonplace. Culture is not always there to help its hosts - sometimes it acts to manipulate and sabotage them for the benefit of others. Addictions caused by drugs, pornography and chocolate gaueau typically don't benefit their hosts, but rather benefit the C.E.O.s of companies that push those sorts of product. Organisms need a cultural immune system to help them to weed out these harmful cultural traits. From my perspective, missing out so much of the negative side of culture results in an unbalanced and incomplete treatment.
While Mesoudi's call for a Darwinian synthesis for the social sciences is to be endorsed, the social sciences have repelled biologically-inspired invasions before on multiple occsations. They are well adapted to an ecosystem consisting of regular attempted raids from biologically-inspired theorists. One of the contributors to these failures was that the biology was wrong. While obviously, too much further delay would be undesirable, we should try to make the science as good as we reasonably can this time - or at least give it our best shot. A crippled symbiosis-free version of Darwinism would only bring the social sciences up to the biology of the 1940s. We should be able to manage better than that.
Another complaint is that Mesoudi slams the concept of evolutionary progress - pointing to unilinear progress theories that inspired social Darwinism and claiming the evolution is a ladder - not a bush. However, progress in organic and cultural evolution is just too obvious to deny. Attempts to deny it appear to stem mainly from the notion of political correctness. The idea has been promoted in modern times by the Marxism-inspired theorist Steven J. Gould. I think the political subtext in this case similar to the one in Gould's farcical book about intelligence testing: to promote equality, by making sure that all people and societies are equally evolved. Instead of such nonsense, evolution is better viewed as a giant optimisation process, set up to maximise entropy. As such it is incredibly directional. It is very strange to hear people denying evolutionary progress in modern times, when it is staring us so clearly in the face. I think scientists should unite in pointing out what nonsense progress denialism really is.
Though promoting the role of evolutionary theory, Mesoudi doesn't really go into the game theory, chaos theory, cybernetics, maths - and the recap on the basics of the scientific method - that would also be needed to unite the social sciences. However, given his focus in this book, that seems to be excusable.
A few less-significant criticisms:
Mesoudi dismisses Campbell's Blind Variation with Selective Retention (BVSR) thesis as being neoDarwinian - for insisting on blind variation. However, this criticism appears to be based on a popular misunderstanding of Campbell's idea. Contrary to what the name might suggest, Campbell did not claim that evolutionary variation was "blind". His claim was more like: either variation is blind or it is based on knowledge previously obtained, in which case there should still be some element of blind variation involved. That idea is quite compatible with many kinds of directed variation - so the existence of such variation does not contradict Campbell's idea. I'm not claiming that Campbell was right here - just that variation that is biased towards being adaptive is perfectly consistent with his idea.
Mesoudi discusses the controversy over whether cultural inheritance is Lamarckian. He cites those that claim that it is not - but doesn't really explain their argument - so a reader unfamilar with this topic can't easily make out the details of the case that Mesoudi is arguing against. A common criticism of the claim that cultural inheritance is Lamarckian is that similar arguments usually also classify dogs passing on "acquired" fleas to their offspring as being "Lamarckian inheritance" - which is contrary to common usage of the term "Lamarckian inheritance" in biology. Mesoudi's examples of innovation appear to be vulnerable to this objection - and it is a pretty fatal one - so these examples seem to be wasted.
Mesoudi - correctly - says that Lamarckian inheritance depends on the genotype/phenotype split. Then he then gives an "internalist" statement of that split - which places the cultural genotype in human brains and the cultural phenotype in behaviour and artifacts. Externalists probably won't find an argument based on these premises very convincing. What would be more convincing is the existence of a non-trivial developmental process. For example, if a cake was being baked, there would be no doubt about where to put the phenotype/genotype split. However, Mesoudi doesn't give such an example - leaving the location of the cultural phenotype merely assumed - and so failing to make much of a case for Lamarckian inheritance. I don't disagree with Mesoudi's conclusion - but I think that his supporting argument would only convince other internalists - which doesn't seem to be worth very much.
A few other differences and criticsms:
Mesoudi apparently thinks that non-cumulative cultural change does not qualify as being a form of Darwinian evolution - while, surely, it does.
Mesoudi offers a rather sympathetic treatment to cultural group selection - whereas I am more critical. For example, Mesoudi offers competition between firms as a modern example. However employees move between firms constantly, carrying genes and culture with them. It is true that there are non-disclosure agreements - but their effect is limited. When firms go bankrupt, their employees do not die, and much of the corporate culture is carried away by them - or else sold as "intellectual property" assets. With this much flow of genes and culture going on between organisations, it would be very difficult to make any kind of group selection model operate successfully.
Towards the end of the book Mesoudi attempts to explain why humans have cumulative culture while other animals do not. Accepting this premise for the sake of argument, Mesoudi gives a rather inconclusive analysis that manages to miss out a number of what I consider to be the main candidates.
To summarise, this is a great book on an important topic. It is a book which I was waiting to read all year. I do think there are some rather glaring omissions, though - as well as some rather uneven coverage of the field's topics. I enjoyed the literature summary - though perhaps a general reader might get a little bogged down by all the details. It's great that we have Mesoudi working in this field. It badly needs outstanding communicators to help get its message across to the rest of the world.
Many modern academic students of cultural evolution seem to share a common problem with understanding how cultural evolution operates. Though some pay lip service to the idea, they don't seem to fully appreciate that culture's relationship with human hosts is a symbiosis.
Some quotes (some of which I have discussed before) illustrate the syndrome:
Kevin Laland and Gillian Brown, Sense and Nonsense (2004, p.253):
Social transmission can occur vertically (that is, from parents to offspring), obliquely (from the parental to the offspring generation; for instance, learning from teachers or religious elders) or horizontally (that is, within-generation transmission such as learning from friends or siblings). Of course, genetic inheritance is exclusively vertical and hence, as social transmission frequently occurs through some combination of these modes of information transmission, cultural evolution may commonly exhibit commonly exhibit quite different properties from biological evolution.
Among humans, genes can only pass unidirectionally from one generation to the next (vertically), normally through intimate contact. But ideas (or “memes”) now regularly pass between individuals distant from each other in space and time, within generations, and even backwards through generations. Through mass media or the Internet, a single individual can influence millions of others within a very short period of time.
William Durham (1991, p.193) says:
genes usually cannot be transmitted independently of the reproduction of their carriers. This constraint obviously does not apply to memes.
We do know that culture is most ungene-like in many respects. Culture has the principle of inheritance of acquired variation (what one person invents another can imitate). We are not necessarily blind victims of chance imitation, but can pick and choose among any cultural variants that come to our attention and creatively put our own twist on them. we don’t have to imitate our parents or any other specific individuals but can always be open to a better idea, or own invention or someone else’s.
Alex Mesoudi, Cultural Evolution (2011) has a similar passage:
One of the more obvious differences between cultural and biological evolution involves the potential transmission pathways each involves. Genetic inheritance is often thought of as being exclusively vertical and biparental, with genetic information transmitted in equal amounts from two parents to a single offspring. In culture, on the other hand, one can learn beliefs, ideas, skills, and so forth, not just from one's biological parents (termed "vertical cultural transmission"), but also from other members of the parental generation ("oblique cultural transmission") and from members of one's own generation ("horizontal cultural transmission").
...though Mesoudi continues by acknowledging:
In fact many of these pathways of cultural transmission have parallels in biological evolution.
...although he fails to mention any of the key phenomena of mutualism, partasitism or symbiosis.
Most of the material above is completely wrong. Symbionts (parasites and mutualists) commonly pass "horizontally" between humans. Parasite genes are shared horizontally by kisses, sex, holding hands and sneezing. Mutualist symbionts and their genes are shared between humans at gardening shops, farms, seed shops and fruit shops. Oblique transmission and transmission "backwards" - down the host generations - work in a similar manner. It should be a matter of acute embarrassment among theorists of social evolution to have missed this.
Such symbiont exchange is by no means confined to humans or other creatures with culture - it occurs ubiquitously in the animal kingdom.
In my experience, many of the misunderstandings of memetics actually turn out to be misunderstandings of how biological evolution works. This example is a case in point.
These academic students of cultural evolution usually go on to say that - because of these differences, we need new models to deal with the situation - and then they go on to develop elaborate extended genotype models to deal with the situation. No! That is not how science is done. The existing models of organic symbiosis handle all these cases just fine. We do not need a raft of new models just to deal with the case of organisms whose genes happen not to be made out of DNA.
Mesoudi's defense of this practice reads:
Nevertheless, most quantitative models of genetic inheritance are indeed based on the assumption of vertical inheritance, making it necessary to construct models tailored specifically to the cultural case.
Not everyone in academia gets this wrong. David Hull, for example was pointing out this mistake back in 1988:
In this connection, commentators often state that biological evolution is always vertical whereas conceptual evolution is likely to be "horizontal". By this they mean that the transmission of characteristics in biological evolution is always from parent to offspring (ie, inheritance). Characteristics always follow genes. In point of fact, biological evolution is not always vertical, even when characteristics follow genes. For example, it is horizontal when bacteria, paramecia, etc. exchange genetic material. Horizontal transmission can even be cross-lineage, as when viruses pick up genes from an organism belonging to one species and transmit them to an organism belonging to a different species.
There are a few cases of recognition of symbiosis:
Most mathematical models of cultural evolution derive from epidemiology. The terminology of "horizontal transmission", "vertical transmission" and "oblique transmission" comes from epidemiology. Epidemiology itself is mostly - though not exclusively - concerned with symbiosis.
Boyd and Richerson (1985) have three sentences on symbiosis. They say:
Horizontal transmission is analogous in some ways to the transmission of a pathogen
...and...
The item of culture being spread horizontally acts like a microbe that reproduces and spreads rapidly because it is "infective" and has a short generation length compared to the biological generation length of the host. Fads and fashions and technical innovations are familiar examples.
Boyd and Richerson (2005, p.165) has a paragraph on symbiosis:
The nonparentally transmitted parts of culture are analogous to microbes. Our immune system evolved to kill microbial pathogens but it also allows us to acquire helpful symbionts. As we know all too well, microbial pathogens are common, despite the sophistication of the immune system. One reason is that we are not the only players in this game. Natural selection helps parasites trick our immune system. Since microbial populations have short generation times and large populations, parasite adaptation can be very rapid. The psychology of social learning is like an immune system in that it is adapted to absorb beneficial ideas but resist maladaptive ones. And, like the immune system it is not always able to keep up with rapidly evolving cultural “pathogens.”
This section is pure memetics. They also implicitly endorse symbiosis in their section on "selfish memes" (p.153-154).
An empirical study of the spread of heroin addiction describes the close resemblance of its dynamics to the spread of disease that requires intimate contact (Hughes and Crawford 19721. Addiction is spread along chains of close friendship. Addicts remain infectious only in the early stapes of addiction, while the p1easurabte aspect of the drug still outweighs the manifest disability of advanced addiction. Only a limited population of susceptible individuals is at risk of acquiring the addiction even if exposed. Many simple epidemiological principles probably apply to pathological cultural traits - e.g., parents notice that the incidence of minor microbial infections and various obnoxious habits in children increase together when they first go to school. Crowded classrooms of young susceptibles are the ideal environment for the spread of pathogens of both types by horizontal transmission among the children!
...and there is a fairly specific endorsement of the idea from Peter Richerson here:
I think it is near to undeniable that cultural variants are sometimes selected to become selfish pathogens along the lines that Dawkins suggested. Since some cultural variants can spread rapidly among people, as in the case of fads, they rather resemble the life cycle of a viral or bacterial pathogen.
Mesoudi and Jensen (2010) offer a four-point summary of the evidence for cultural group selection. It doesn't seem terribly impressive.
Superficially, the claim that culture-level group selection has created DNA-level social instincts supporting human ultrasociality is a strange one.
There's a much simpler and better hypothesis that explains why culture has promoted human ultrasociality that arose over a decade ago from within memetics. The idea is that memes need humans to get in contact with one another in order for them to reproduce. The hypothesis is covered on the page: Memes and the evolution of human ultrasociality.
The idea proposes straight-forward individual-level benefits to social behaviour with other humans - namely:
Ultrasocial individuals acquire more memes (and organic symbionts), and these are (on average) good.
Ultrasocial individuals get to influence others with their memes (and organic symbionts) more - spreading their own influence in the process, and gaining reputation and status credits that can be cashed in later.
This explanation complements explanations involving, virtue signalling, kin selection and reciprocal altruism.
Now it may be that these benefits don't outweigh the costs of some forms of altruism - but such expensive altruism is rare, and can be explained well by virtue signalling, over-generalisation and cognitive resource limitation.
There's very little need to invoke cultural group selection, it seems. There is little sign of phenomena that require explanations based on high-level selection. It is not clear why is the literature in the area is so full of such explanations - when there is a much simpler and more obvious hypotheses on the table.
References
Mesoudi, Alex & Jensen, K. (2010) Culture and the evolution of human sociality. In: The Oxford Handbook of Comparative Evolutionary Psychology, edited by J. Vonk & T. Shackelford. Oxford, UK: Oxford University Press.
Many enthusiasts for the idea that culture evolves also seem to favour the idea of group selection.
Ed Wilson has returned to the "group selection" camp in recent years. David Sloane Wilson promotes both cultural evolution and group selection.
Something called "cultural group selection" is promoted by Boyd, Richerson, Mesoudi, Henrich, Gintis and Nesse as being a significant force which has supposedly helped to shape human ultrasociality.
Many of these authors claim that cultural group selection is dramaticallly different from group selection in the organic realm. For example, Boyd and Richerson (2005) write:
selection between large groups of unrelated individuals is not normally an important force in organic evolution. Even very small amounts of migration are sufficient to reduce the genetic variation between groups to such a low level that group selection is not important. However, as we will explain below the same conclusion does not hold for cultural variation.
This article argues that "cultural group selection" actually closely mirrors group selection acting on parasites in organic evolution.
Enthusiasts for "cultural group selection" claim that cultural evolution acts to rapidly create between-group differences and jelps to prevent gene flow between groups. The between-group differences may also result in one group having a selective advantage. It is conjectured that these differences are sufficient to overcome the problems usually associated with group selection in the organic realm.
However, in the organic realm, evolution of pathogens also acts to rapidly create differences between populations. Pathogens can also cause between-group differences in fitness. This was seen (for example) during the European invasion of North America - where smallpox alone killed 25% of the Aztec population and between 60% and 90% of the Inca population.
One of the mechanisms proposed by Mesoudi and Jensen (2010) that would act to assist cultural group selection is that migrants adopt the social norms of their new group - acting to preserve group variation.
Migration is also a big problem for genetic group selection: in many group-living species one sex typically disperses out of the group, reducing between-group genetic differences. In humans, however, migrants often acquire the social norms of their new cultural group, maintaining between group cultural variation and consequently allowing cultural group selection to act.
However, much the same thing happens in the organic realm as well: migrants go on to contract the parasites of the groups they migrate into.
Sometimes migrants successfully introduce parasites into their new group. However that happens with culture too - migrants can carry beneficial ideas and inventions that subsequently spread like a plague through the new group.
Mesoudi and Jensen (2010) propose that the evolution of modern corporations may exhibit a form of group-level selection on human culture. However, there employees regularly drift between organisations, carrying skills and knowledge with them. NDAs and employment contracts attempt to prevent such losses, with limited success.
Corporations do represent large-scale cultural entities that compete with one another for human resources. However, flu strains also compete with one another on a large scale for access to human hosts. Just as employees of two different corporations may attend the same Masonic meetings, and the same bridge club, so hosts of different strains of flu virus may be infected weith different strains of warts virus and different strains of syphylis.
The broad equivalence between the cultural and organic realms in this area should come as no surprise for those who are already accustomed to treating culture as composed of rapidly-reproducing symbionts with "genes" which are not made out of DNA.
Another issue in this area concerns whether group selection on culture (or parasites) results in group selection on the level of the DNA genomes of their hosts. Between-group differences, sharper group boundaries and differences in fitness between groups may result in the deaths of host groups, along with the deaths of their culltures and parasites.
However, it is fairly common for invaders to spare native women. Also, it seems implausible that between-group migration rates are low enough to prevent individual-level selection swamping group selection when considering only DNA inheritance. Group selection in the human DNA-gene pool is probably a fairly minor force.
Are there differences between groups of humans with different cultures and groups of humans with different parasites which are relevant to the issue of group selection? Yes: culture acts as visible marker which acts to distinguish different groups. That may make the boundaries between groups crisper, and reduce gene flow between them. Parasites probably do that to a much reduced extent. Immigrants are less clearly marked out by their different parasites than by their different cultures - since their parasites are quite often invisible latent infections. They might hesitate to enter new groups through fear of the group's parasites, though. Similarly, groups might reject imigrants out of concern for acquiring their parasite load. However, xenophobia based on cultural cues is probably a more intense force.
Proponents cite conformity and punishment as mechanisms which stabilise groups so they act as independent units. However, such forces apply mainly within the moral realm - and not to (say) the spread of innovations. Some aspects of culture are more likely to spread between groups - and are less likely to be subjected to group-level selection forces. Spread of innovation is one of the main factors strong enough to produce significant group-level fitness differences.
These issues are probably not major difference between the organic and cultural realms as far as group selection goes. In conclusion, the "cultural group selection" enthusiasts appear to be greatly exaggerating the differences between the cultural and organic realms. Differences between the applicability of group selection to the two domians are probably mostly fairly minor. If culture is to be used to argue that group selection is an important force, much the same argument applies to parasites in the organic realm.
References
Mesoudi, Alex & Jensen, K. (2010) Culture and the evolution of human sociality. In: The Oxford Handbook of Comparative Evolutionary Psychology, edited by J. Vonk & T. Shackelford. Oxford, UK: Oxford University Press.
Richerson, Peter J. and Boyd, Robert (2005) Not by Genes Alone: How Culture Transformed Human Evolution. University of Chicago Press: Chicago, IL.
Alex Mesoudi recently wrote a paper about the possibility of a ceiling on cumulative cultural evolution. The abstract says, in part:
Yet previous analyses of cumulative cultural change have failed to consider the possibility that as cultural complexity accumulates, it becomes increasingly costly for each new generation to acquire from the previous generation. In principle this may result in an upper limit on the cultural complexity that can be accumulated, at which point accumulated knowledge is so costly and time-consuming to acquire that further innovation is not possible. In this paper I first review existing empirical analyses of the history of science and technology that support the possibility that cultural acquisition costs may constrain cumulative cultural evolution. I then present macroscopic and individual-based models of cumulative cultural evolution that explore the consequences of this assumption of variable cultural acquisition costs, showing that making acquisition costs vary with cultural complexity causes the latter to reach an upper limit above which no further innovation can occur.
Some brief feedback: The argument is based on the idea that:
Assuming that people have a limited, finite amount of time in their lives to devote to acquiring previously accumulated knowledge, there would theoretically come a point at which so much has to be learned that there is no time remaining for innovation, and accumulation will cease.
I don't think Mesoudi is making enough of an effort to consider the effects of technological development. Machines and computers have potentially unlimited lifespans, very large memories and are widely expected to exhibit impressive cognitive capacities in the non-too-distant future. Their symbiosis with humans seems likely to essentially demolish the constraints that Mesoudi discusses. Which is not to suggest that innovation will continue forever, just that the human lifespan seems unlikely to constrain it.
Now that cultural evolution is making such good progress in academia, can memeticists just leap onboard?
I don't think so - not just yet, anyway. Apart from the whole issue of long-winded terminology, although these are very similar theories, they have a different emphasis and history - and memetics is still much, much better in some areas. The approaches obviously need to fuse - but at the moment they still have some significant incompatibilities.
Alex Mesoudi - in his recent book - has a soundbite which encapsulates one of the differences in the approaches of academic researchers in cultural evolution and memetics.
Mesoudi says:
In a typical cultural evolution model, a population is assumed to be composed of a set of individuals, each of whom posseses a particular set of cultural traits. A set of microevolutionary processes is specified that changes the variation of those traits over time.
I can verify that this is a pretty accurate description of what most cultural evolution models in academia are like.
By contrast in memetics, there are organic creatures and cultural creatures - two interwoven lifecycles to consider. These typically play the role of host and endosymbiont. The endosymbionts are usually parasites, or mutualists. All the standard models of symbiosis in biology are thus applicable to the cultural realm, and can simply be imported.
On page 7 of Culture and the Evolutionary Process, Boyd and Richerson give what appears to be an argument against such cultural creatures. They say:
This does not mean that cultures have mysterious lives of their own that cause them to evolve independently of the individuals of which they are composed. As in the case of genetic evolution, individuals are the primary locus of the evolutionary forces that cause cultural evolution and in modelling cultural evolution we will focus on observable events in the lives of individuals.
This seems to be fundamentally the wrong approach. It is like saying: to study the evolution of AIDS, we should focus on on observable events in the lives of the AIDS sufferers. Yes, that method will result in some progress - but it is a fundamentally misguided approach - because it ignores the HIV virus itself.
I have looked at a lot of the literature and I don't think this is just a case of model simplification to produce something tractable. Cultural evolution researchers have a real blind spot when it comes to cultural creatures - although they do sometimes receive an occasional mention - usually as an "analogy". I give some examples of this in my book.
A more correct and complete model would include cultural creatures and organic creatures in a symbiosis. The cultural creatures do evolve outside of their organic hosts. Books get burned. CDs get scratched, hard disc drives crash, and computers filter and process memes. Yes, you can attempt to model these as "microevolutionary transmission processes" - but that produces nasty complexity - it is much better and much simpler to just recognise cultureal avolution as dominated by symbiosis - and then reuse existing symbiosis-based models.
OK - so cultural creatures may sound like something out of science fiction - but they are essential for understanding human culture. These things have genotypes, phenotypes, and their own lifecycles - it is just obvious that they are best treated as symbionts - if you stop and think about it for a moment or two.
Due to only attempting to model half of the creatures in the relationship, cultural evolution in academia has become a feeble and dumbed-down version of memetics - which got this right from the very beginning. The academic researchers involved apparently need to pull their socks up in this area - before they go very much further.
I tracked down Alex Mesoudi's take on memes. He describes memetics as being a "fad". In Cultural Evolution, page 42, he says:
Memetics makes the neo-Darwinian assumption that culture can be divided into discrete units that are inherited in a particulate fashion, like genes. It also assumes that memes are transmitted with high fidelity, this being one of the defining characteristics of a replicator according to Dawkins.
For me, this is disappointing material. Mesoudi fails to provide references. As far as I can tell, Dawkins did not, in fact, claim that high fidelity transmission was one of the defining characteristics of a replicator.
What Richard Dawkins actually says in The Selfish Gene (page 17) is:
A third characteristic of replicator molecules which would have been positively selected is accuracy of replication. If molecules of type X and type F last the same length of time and replicate at the same rate, but X makes a mistake on average every tenth replication while Y makes a mistake only every hundredth replication, Y will obviously become more numerous.
Dawkins clearly says that accuracy of replication is a trait of replicator molecules which is subject to positive selection. That means that the replicator molecules varied in their replication accuracy. This is completely the opposite of high fidelity transmission "being one of the defining characteristics of a replicator" - since it is saying that replicator molecules varied in their transmission fidelity and were subject to selection based on that variation.
Mesoudi is attributing to Dawkins the idea that high fidelity transmission is a defining characteristic of replicators - which is the opposite of what Dawkins said in The Selfish Gene. Dawkins went on to offer an explicit definition of the term "replicator" in The Extended Phenotype - and that doesn't include the concept of high-fidelity transmission either.
This material about memetics assuming high fidelity transmission appears to be F.U.D. As far as I can tell, the origin of it is a 1985 book on the topic - "Culture and the Evolutionary Process" by Robert Boyd and Peter Richerson. I figure they probably needed selling points for their variation of cultural evolution - and the ability to handle analog transmission was one of the ones they explicitly went for - on page 37. For that to be true, previous authors needed to have assumed discreteness. They took the conventional meaning of the word "replicator", and either failed to notice or ignored the fact that Dawkins (1982) had explicitly defined it as:
I define a replicator as anything in the universe of which copies are made.
In this definition, high fidelity transmission is conspicuous by its absence.
As far as I can tell, that is how the idea of high fidelity transmission is a defining characteristic of memes most likely arose. It is a rather sad story - but it is not clear why it is that this misunderstanding still being perpetuated some 26 years later.
Memetics doesn't require high fidelity transmission. The most successful memes do indeed exhibit high-fidelity transmission - just as Dawkins said. They have migrated onto the internet, where transmission is digital - resulting in hundreds of millions of bit-identical copies of the latest Lady Gaga song - but that doesn't mean that every single meme is transmitted with high fidelity. That would be ridiculous. The idea that high fidelity transmission is required by memetics is just a bunch of nonsense.
The researchers involved have been advised about this before. For example here:
In a section entitled “cultural variants are not replicators”, they repeat the false claim that copying must be perfect for a replicator to count as such
Boyd and Richerson first introduce replicators as “material objects that are faithfully copied”. It certainly isn't Richard Dawkin's view who described replicators as “any entity in the universe of which copies are made”.
I will repeat the message again here: memetics does not require high fidelity data copying. The idea that it does is just a basic misunderstanding - originating - as far as I can tell with Boyd and Richerson, 1985, p.37. Their claim seems patronising to me. It is basic information theory that you can produce high fidelity information transmission (which is much more important for adaptive evolution) from low fidelity data transmission.
Boyd and Richerson were not attacking a straw man - since I actually have seen two people mess this point up:
John Maynard-Smith - In "Evolution-Natural and Artificial" (1999), John claims that adaptive evolution requires digital inheritance - and it makes some other rather silly claims for good measure. That is somewhat embarassing, but it has nothing to do with memetics - because Maynard-Smith was not a supporter.
David Hull - In "Science as a Process" (1988) David defined a replicator as being: "an entity which passes on its structure largely intact in successive replications."
Hull goes on to talk about entire populations passing on their structure "largely intact". What is "structure"? Hull says to see "Social Being" by Harre (1979) for more about that. However, I think this leaves only a little room for a sympathetic interpretation involving information since "information" and "structure" seem to be two rather different concepts. I think this puts David Hull's attempt to form a basis for evolutionary theory into the category of being wrong - or, at best, misleading.
Hull makes one passing mention of "memes" in "Science as a Process", on page 406. It is plain from his other writings that he endorsed the term. However, I do not endorse Hull's formulation. I think he made a mistake - or at least was being misleading. However, please don't attribute to memetics Hull's mistake. Lumsden and Wilson made some mistakes too, but I don't go around saying that gene-culture evoultion has got it all wrong.
The idea of high fidelity transmission is genuinely important for evolutionary theory - because information needs to be transmitted with high fidelity in large-scale culmulative adaptive evolution (with some caveats about incredibly strong selection pressures and mysterious sources of directed mutations). However it is possible to have high-fidelity information copying with low fidelity data transmission, as Shannon and Von Neumann previously explained long ago. We actually see such things in the modern world in the form of self-encrypting computer viruses. The data is wildly different in each generation, but the information is transmitted with high fidelity. So, it is high fidelity transmission of information - not data - from place to place that is the correct idea which associates the concept of "high fidelity" with the fundamentals of evolutionary theory.Also, not all of the transmitted information has to be conveyed with high fidelity, just some of it. You need some kind of mutual information between ancestors and descendants, or evolution is not going to be very "cumulative". There's a page with more details about this point here.
This is not a completely trivial point, and I can understand how people could get into a muddle about it. However, now that we have the internet, the time for getting into pointless muddles should be over.
I think the people from academia who persist in spreading this kind of material around need to be explicit about where they are getting it from, quoting chapter and verse. So far, there hasn't been very much of that. Boyd and Richerson (1985) cited "The Selfish Gene" and "The Extended Phenotype". Page numbers please. Boyd and Richerson (1985, p.266) pointed to the forward to "The Meme Machine". There Dawkins defends against the charge that cultural evolution does not have good enough fidelity to exhibit adaptations - which is a perfectly reasonable point to make. Dawkins has plenty of material in those books which flatly contradicts the alledged business about high fidelity copying - so I figure Boyd and Richerson can't have been trying very hard to find a sympathetic interpretation. If people remain incapable of quoting the incriminating chapters and verses, I figure they are eventually going to have to shut up about it.
In the mean time, please try to remember: neither genetics nor memetics requires high-fidelity data copying. The idea that they do is just a fallacy.
Memetics is the cultural sub-branch of genetics, which is defined as being the science of heredity. How inheritance takes place is an implementation detail in genetics and, similarly, it is an implementation detail in memetics. This should not be that difficult to understand.
As for memes being "discrete" and "inherited in a particulate fashion", it is just a matter of fact that memeplexes can sometimes get sliced up during transmission, just as geneplexes can, and - after being sliced - some heritable information is on one side of the slice and some of it is on the other - producing two or more "discrete" pieces - or "particles" - with potentially different pathways to immortality or oblivion.
Do memeplexes have preferred "break" points - rather like the grooves on a bar of chocolate? Sometimes they do, and sometimes they don't - and DNA sequences are much the same - occasionally there are preferred points of division (e.g. see restriction enzymes), but usually there are not - and the divisions that take place during meiosis can take place practically anywhere.
Hull (2001, p.120) addresses the "particulate" criticism, as follows:
Some authors argue that no general analysis of selection process equally applicable to biological and conceptual evolution is possible because genes are "particulate" while the units in conceptual replication are highly variable and far from discrete. In point of fact neither biological nor conceptual replicators are all that particulate. In both cases, the relative size of the entities that function either as replicators or as interactors is highly variable and their boundaries sometimes quite fuzzy.
Contrast this with Mesoudi (2011, p.46):
However, whereas genetic inheritance is particulate, cultural inheritance in many cases appears to be non-particulate.
In what senses is genetic inheritance particulate, though? In sexual creatures, nucleotide sequences can - and do - divide at practically any point. Yes, there are start and stop codons - but that takes us out of the realm of genetics and into the world of development. From a genetics perspective, about the only sense in which genes are "particulate" is that they don't divide half-way through a base pair. In summary, the supposed "particulate" nature of genetic inheritance is just nonsense. Organic genetic expression is somewhat particulate - at least if you can cope with ideas like "particles within particles" and "overlapping particles" - but genetic inheritance, not so much.
Dawkins clearly allowed for "non-particulate" replicators in his 1983 "Universal Darwinism" essay - saying:
A full science of Universal Darwinism might consider aspects of replicators transcending their detailed nature and the time scale over which they are copied. For instance, the extent to which they are "particulate" as opposed to "blending" probably has a more important bearing on evolution than their detailed molecular or physical nature.
Dawkins is presumably talking about recombination there. There is a difference between genetic and cultural evolution in terms of what types of recombination are permitted - with most genetic recombination being in the form of splicing, while memetic recombination can involve averaging, extrapolation and interpolation. Memetics has permitted these kinds of recombination from the beginning. There is no version of memetics that does not allow for "blending" recombination - except in form of straw men in the minds of critics.
Population memetics no more requires particulate memes than population genetics requires particulate genes. In both cases, it is the researcher who selects the boundaries of the entities whose frequency they are measuring.
From my perspective, the alleged "discrete" and "particulate" problems supposedly associated with memes represent more daft storms in a teacup.
Laland and Brown said that cultural evolution had been characteried by Sense and Nonsense - and I think that the "discrete" and "particulate" criticisms take us well into the "nonsense" territory.
These are not real problems but rather show all the signs of being marketing material concocted by rival researchers keen to find some way of distinguishing their own ideas from those of others that came before them with much the same notions.
Cultural Evolution: How Darwinian theory can explain human culture and synthesize the social sciences.
It seems likely to be a fairly major academic work on the topic.
Alex Mesoudi is a lecturer in Psychology at the University of London. He has been working hard on the study of cultural evolution since around 2002 - and has published numerous papers on the topic.
His 2005 PhD thesis on the topic is a fine document - especially part 1 - which summarises the evidence for cultural evolution.
Laor and Jablonka devote much of their review of Mesoudi's "Cultural Evolution" book
to a call for development and systems theory. Many of their points read like criticisms of memetics.
I read this paper recently:
In a recent article titled: "
Many modern academic students of cultural evolution seem to share a common problem with understanding how cultural evolution operates. Though some pay lip service to the idea, they don't seem to fully appreciate that culture's relationship with human hosts is a symbiosis.
Mesoudi and Jensen (2010) offer a four-point summary of the evidence for cultural group selection. It doesn't seem terribly impressive.
Alex Mesoudi recently wrote 
Now that cultural evolution is making such good progress in academia, can memeticists just leap onboard?
I tracked down Alex Mesoudi's take on memes. He describes memetics as being a "fad". In Cultural Evolution, page 42, he says:
Alex Mesoudi's 
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