How Darwinian is cultural evolution?

Dual-Evolution-Systemby Scientia Salon

This is a paper published by Nicolas Claidière, Thomas C. Scott-Phillips and Dan Sperber in the Philosophical Transactions of the Royal Society (Series B, Biological Sciences), in 2014 (here is the open access link to the full article).

The abstract states:

Darwin-inspired population thinking suggests approaching culture as a population of items of different types, whose relative frequencies may change over time. Three nested subtypes of populational models can be distinguished: evolutionary, selectional and replicative. Substantial progress has been made in the study of cultural evolution by modelling it within the selectional frame. This progress has involved idealizing away from phenomena that may be critical to an adequate understanding of culture and cultural evolution, particularly the constructive aspect of the mechanisms of cultural transmission. Taking these aspects into account, we describe cultural evolution in terms of cultural attraction, which is populational and evolutionary, but only selectional under certain circumstances. As such, in order to model cultural evolution, we must not simply adjust existing replicative or selectional models but we should rather generalize them, so that, just as replicator-based selection is one form that Darwinian selection can take, selection itself is one of several different forms that attraction can take. We present an elementary formalization of the idea of cultural attraction.

I actually disagree with the authors when they wish to treat cultural evolution as “Darwinian,” and in fact I think they unwittingly make a good argument that it is not, or at the least not in great part. Still, the excerpts below give an idea of a number of interesting notions discussed in the paper.

Of course, the analogy with biological evolution is not perfect. For example, variations in human cultural evolution are often intentionally produced in the pursuit of specific goals and hence are much less random than in the bio- logical case.

In this paper, we argue that there are important aspects of cultural evolution that do not fit even within a selectional model, and which are better explained and modelled as part of the broader population and evolutionary frames. Specifically, we argue that cultural evolution is best described in terms of a process called cultural attraction, which is populational and evolutionary, but only selectional under certain circumstances.

While some cultural items may indeed be propagated by imitation and other forms of copying, it is clear that a large number are not. In particular, many are also (re-)constructed. For example, a student taking notes in a lecture does not simply copy any spelling error that the lecturer happens to write down, but will in fact, in her own notes, correct the error and in doing so re-construct the correct spelling. As such, cultural propagation is partly preservative, but also partly (re-)constructive, to different degrees in each particular case. As such, it is not only a matter of inheritance, as is gener- ally the case for biology, but also of reconstruction. Whichever of these is more important in any given case is an empirical question, but either way, the direct analogy with biological evolution is considerably weakened by this fact.

 

How deep is the analogy between biological and cultural evolution? Memetics assumes that it is deep indeed; that the main relevant details of the biological case have direct equivalents in the cultural case, such that there is, for example, a cultural phenotype, which achieves a certain level of (inclusive) fitness, which will in turn determine the phenotype’s relative success in the population. Selectionist approaches loosen the analogy somewhat, moving from a replicative frame to the more general selectional frame. We have argued that the analogy should be loos ened further: cultural evolution is broadly Darwinian, in the sense that it is a population-level evolutionary phenomenon, but there is no empirical reason to think that it sits entirely or even in general within the selectional frame.

Another important disanalogy between biological and cultural evolution is the mechanisms by which traits propagate through a population. In biology, the mechanisms of transmission are in general only preservative. In the cultural case, however, the mechanisms of transmission are many and varied, and include both preservative and constructive sub-mechanisms.

Both attractors and the process of attraction are statistical notions. They do not denote a type of causal process or the outcome of a specific such process, and as such they do not pro- vide explanations of cultural phenomena. Rather, they provide relevant descriptions of what is to be explained. Attraction should instead be explained in terms of factors of attraction. Factors of attraction in an epidemiological population will generally be partitionable into two classes: relevant properties of the individual members of the host population (such as the psychological and biological susceptibilities of humans); and relevant properties of the environment of these individuals, including the demographic properties of the host population itself.

Darwinian selection leads to the maximization of inclusive fitness, and this explains the appearance of design in the natural world. Is there an analogous result for cultural attraction? As selection is a special case of attraction, design is possible and in some cases explicable in standard Darwinian terms. Having said that, such explanations will not apply generally, and may not even apply commonly.

A general, formal statement of what cultural attraction leads to does not presently exist, and we see the development of such a statement as a major goal for future modelling work.

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61 replies

  1. To Aravis:
    Despite the paper’s short digression into painting, I think art is safe from biologizing. I don’t think there is any sort of reductionist program toward culture at all. The authors should correct me if I’m wrong.

    We should be aware that anthropologists’ use of the word “culture” is very broad, and includes such things as “you say day-ta, and I say, dah-ta” the spreading of the meme “Mine eyes have seen the glory of the burning of the school…” among the elementary school population of the U.S., and the neolithic tool kit.

    To Sperber et al,
    I find some inspiration in “intuition pump” for a class of possible studies of culture on the internet.
    First of all I suggest that Dawkin’s “selfish gene” should be viewed as a conceptual entity, like mathematical constructs — the structure of the snippet of DNA rather than the actual snippet, and we might think metaphorically of this conceptual object “trying” to maximize instances of itself — but really we should mean maximizing organisms of a certain related population, having the particular gene inserted in a particular part of a particular chromasome. This pairing is necessary to avoid the absurdity of the homeobox (pardon me if I get this wrong) gene having a grand scheme for maximizing its instantiations across all species. Since conceptual objects no more than snippets of DNA “try” to do anything, the only way I think we bring this into the world of matter is by considering by instantiating a particular scientist somehow considering manipulations of some representation (in her head or in a computer) of the gene, and considering the effect that some modified version instantiated in one or more members of the population would have on that population going forward … OR looking for instances of a real modification in a population in the wild or in the lab (or in the ancient past), and matching that to empirically observed effects.

    Then again, we would probably not be doing any of this until genetics is much better understood than at present, and we are walking around on the DNA strand as on some archeological site, with some real understanding of what each bit does, and saying A overlays B, or at some point a duplication of C occurred leading to D, with subsequent modification to the 2nd of the twin C’s, and through such means making correspondences between when such and such a feature of language (or Tomasello’s complex of cooperation instincts) emerged.

    Not being ready for any of that, what we *are* apt to do to perform thought experiments along the lines suggested in the 2nd paragraph back, and perhaps deriving mathematical models from these thought experiments.

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  2. Socratic Gadfly,

    This is the point regarding cultural algorithms (CAs): The framework for CAs (in the Reynolds model) has a belief/knowledge space, separate (but interacting with) a population/genetic space. This means that CAs can be non-Darwinian (in the strict sense of genetic algorithms).

    Computational Intelligence: An Introduction
    Chapter 14: Cultural Algorithms
    http://books.google.com/books?id=IZosIcgJMjUC&pg=PA261&lpg=PA261

    Clever Algorithms: Nature-Inspired Programming Recipes
    Cultural Algorithm
    http://www.cleveralgorithms.com/nature-inspired/physical/cultural_algorithm.html

    Humans are the only natural animals with a belief/knowledge space that can evolve (non-Darwinianly) apart from its population/genetic space.

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  3. dbholmes: “I am forced to ask… why Lamarckian is not an apt description?”

    The term “Lamarckian” is usually glossed as “inheritance of acquired characteristics”. It’s not clear to me why what we describe as cultural attraction fits that description. In fact, the arguments in our article could be read as saying: there is no inheritance, properly understood, in cultural evolution. And if there is no inheritance, there can be no inheritance of acquired characteristics.

    Let me expand. Inheritance is a process whereby like begets like. In other words, it is preservative. Replication is preservative, and that is why, in the biological case, we talk of inheritance of genes. We argued in the article that processes of cultural propagation are, with a few special exceptions, not exclusively preservative at all. On the contrary, they routinely involve constructive aspects also; and indeed, this constructive dimension is the product of the proper functioning of the mechanisms of cultural propagation. This important role for constructive processes in cultural evolution means that cultural propagation is not preservative alone, and hence that there is nothing we can properly call inheritance.

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  4. thomscottphillips,

    “the arguments in our article could be read as saying: there is no inheritance, properly understood, in cultural evolution”

    Right. Which would seem to me to exclude the idea that it is a Darwinian phenomenon (see Lewontin’s summary of it above).

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  5. Culture is not a realm of “ideas” nor a “memeplex” (as Dennett would have it). It is an integrated behavioural and cognitive niche created by human social groups. These social groups do not represent biological demographic units (demes) but are independent of them.

    Cultures are, significantly, interactions between a human population and it’s physical environment and evolved ecosystem. It is the planet and it’s living ecosystem that each cultural system represents as a mediating interface with a human biological community. All cultures have three dimensions: 1) resource procurement, processing, and distribution (and economy), 2) human social organization into perform the operations of the economy and to reproduce the biological hosts of the cultural information, and 3) systems of information storage, transmission, and innovation (languages – including music, story telling, cause-and-effect exemplars, and recipes for skilled manipulation of technology).

    Memes might be useful for describing some aspects of the third component, although the use of words like “word”, “phrase”, and “concept” already exist and seem to me to be adequate to the task.

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  6. Hi Coel,

    A fairer summary would be that his original intent was to clarify understanding of the logic of genetic evolution by discussing alternative replicators. Then, later, he occasionally discussed how strongly the idea could be interpreted.

    Well, no, you are talking about what he said in the text. In the endnote that I mentioned he said pretty much what I said he said, I think it was a pretty fair summary.

    You seem to dismiss the idea of a physical instantiation in the brain, but any and all ideas that you currently hold must be physically instantiated as neural-network patterns.

    It is simply not true that I dismissed the idea of physical instantiation. That is not what I said at all. I advisedly talked about the definite physical signature which you clearly do not get in a neural-network and which Dawkins said that he initially invisaged.

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  7. To further explain why culture is independent of biological demes, consider this: a culture can recruit via reproduction, expansion, or by immigration. this means that any particular cultural system can outlive the deme that it started in. There is no reason why, in highly inegalitarian cultures, only a small number of human hosts would leave descendants, by appropriating the bulk of the necessary resources generated by the economy of that cultural system. Failure of reproduction of low ranking hosts due to stress, malnutrition, and disease is a factor in all social species. Humans are not that different. What is however highly developed in humans are these integrated behavioural/cultural ecological niches.

    I believe most of you in this set of comments have not really focussed much on an important fact: humans have biologically evolved cognitive abilities not just to learn one culture and language, they have evolved to learn many. Insofar as music and mathematics are also languages of a kind, one might even say that humans have evolved to be cognitively multilingual and multidimensional. Each individual human can learn to interact successfully in many different cultural systems and languages over the course of a lifetime. Why do you suppose that is? I know, but does anyone else here care to take a stab at answering this?

    The idea that a particular cultural system (such as the ones based on fossil fuel use and industrialized economies) permits faster population growth and relative dominance over competing cultures should not blind us to the fact that these may collapse and fragment. Like biological species, individual cultures can in fact overshoot their resources. Natural selection (Darwinian evolution) applies to cultures, and this is now obvious.

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  8. Hi Thomscottphillips, first I would echo Massimo‘s criticism above. If you leave out inheritance, period, then the point of discussing Darwin at all is lost on me. Even if you say Darwin talks about changes in populations, well there are plenty of changes in populations. Working with stem cells I encounter changes in populations all the time. And it’s not natural selection at work in that case, making such descriptions definitively nonDarwinian.

    Regarding Lamarcke, I think you are now going too narrow on “Lamarckian” as well. While offspring may have characteristics acquired by the parents during their life experience, another form could be that characteristics which would be useful as experienced by the parent are passed on (without the parent ever showing them). In that case there could very well be a constructive element, and not simply preservation. A kind of example we see in genetics (though controversial) is genes being silenced or activated due to life experiences of the adult (for example due to hunger), whose effects are only seen in the children.

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  9. Per Helga “a culture can recruit via reproduction, expansion, or by immigration.”

    Also, by broadcast in a number of formats, book publication and distribution; the existence of libraries, schools, churches, clubs are part of the media through which aspects of culture spread. And in modern time especially, there are intersecting cultures, and (per Helga again) “Each individual human can learn to interact successfully in many different cultural systems and languages over the course of a lifetime.”

    In modern societies there is no unitary culture — belief systems, yes, and tendencies to specific beliefs, and there are the black arts of manipulating what people believe, which we might want to analyze and to counteract.

    Memetics, if there were such a thing, could not have any of the clear boundaries of genetics. What a culture is is fuzzy; who belongs to a given culture or subculture is fuzzy; people belong to multiple subcultures, and their belonging can be weak or strong, and we have no idea how to quantify that.

    Still, Darwin took some interest in the general idea. Did Darwin define Darwinism? Was he a Darwinist? I suppose if you distil the central theme of Origin of Species, you might get Lewontin’s criteria, but as far as I know, Darwin was trying to describe a particular existing phenomenon, not provide a set of axioms for “Darwinian phenomena” generalizable to computer simulations or culture or whatever — nor was he forbidding such generalization.

    And there are various suggestive facts and classes of facts:

    From time to time cultural watersheds occurred, involving a technology (which I’d call part of culture) so superior that it would over time spread throughout the world, and we may be off to a new “age” (e.g. Paleolithic, Neolithic, Bronze, Iron). Spread through what mechanism(s)?

    It would be tidy — i.e. easier to analogize to biological evolution — if the sole impact of that was “have” groups wiping out “have not” groups, but the spread occurs other ways: through absorption of one group by another; by friendly exchange; by spies learning of what another culture has that we don’t. The phenomena resemble evolution in broad outline despite the messy boundaries.

    There are the analogies of culture to epidemiology, sharing general concepts of beachheads, quarantining boundaries, the effects on transmission of environmental factors (weather or the bandwidth of media). Also, a local innovation in the cultural, like a viral mutation, can accelerate the process, as well as favoring one branch of the process at the expense of others.

    “A culture” in modern society seems too unwieldy and badly defined for analysis via rigorous Darwin-like concepts. However, all the ECM examples were of what we might call “micro-culture”, of which we could find more interesting examples, like tendencies to believe X (especially if false), or use of ethnic epithets.

    While cultures are intractable, discussion spaces on the internet might be an ideal place to study microculture and how it responds to changes of environment.

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  10. I think that the position that culture is not heritable is not defensable and it is observable that this is not the case, given historical records of cultural pratices that we keep from long-term ancestors. This conclusion is just a byproduct of the assumption that inheritance has always to be preservative. This is obviously false. Think of any phylogenetics’ transformational series composed of plesiomorphous and apomorphous caracters: inheritance is partialy preservative, but also transformative. The reason for all tetrapods presents four limbs is necessarily due the existence of inheritance, even if those limbs are variable in their forms and functions.

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  11. To Sperber, thomscottphillips, and others:
    EMCs might be not such a toy or mere intuition pump after all.

    A very low cost (researcher time only) method would be analysis of snapshots of a “comment section” of any blog. They are public, instantly accessible, and ofter freely quotable. Also extremely diverse in culture.

    I believe much could be learned from periodic snapshots analyzed for frequency of appearance of specific words, types of expression, indicators of particular beliefs, other bits of “micro-culture” (it is hard to keep from saying “meme” in this context)

    Does a type X expression lead to an increase of type Y expressions in a comment section? Surely we have seen examples of this
    .

    Does attitude A in one contributor produce instances of attitude B in others?

    I am most interested in one practical thing. What can we learn about rules of conduct, or any other design feature of a conversational space, and how they improve or discourage effective truth seeking?

    Social epistemologists try to understand any and all practices — technology, means of recording events in the lab, means of communication, means of rewarding work, the mix of mavericks and conservatives — and what they have to do with the success of science at establishing truth (and they also worry about defining truth, of course).

    It is easy to find in some conversational spaces a culture of rewarding “zingers”. One could study what evolves naturally on such forums, or one could study the effects of certain kinds of interventions by participating in the forums.

    Culture as indicated in a conversation forum seems of great interest in itself, and might also be somewhat of a proxy for that inaccessible thing, lacking a “signature”, culture in a population of human beings.

    I believe one could actually learn something about making communication more productive.

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