Wednesday, May 12, 2010

Cultural Evolution 1: How “Thick” is Culture?

This is the first in a set of posts in which I take up the nature of cultural evolution. I’m using these posts as a medium to think-through my ideas in preparation for a presentation on cultural evolution at the Forum in On the Human, a project of the National Humanities Center. That is presently scheduled for 5 July 2010.
There is no more pressing area of inquiry in the human sciences than those having to do with the relationship between biology and culture. One issue is whether or not culture itself constitutes an evolutionary arena and, if so, how does it work? Specifically, what is the relationship between cultural evolution and biological evolution?

I believe that culture does constitute an evolutionary arena and have published on the subject for almost two decades (cf. Benzon 1996). But I do not want to start there, not quite. Rather, I want to start with a discussion between Peter Richerson and Joseph Carroll in a recent issue of Politics and Culture (an online journal). Richerson (2010a) presented a short essay, “Culture is an Active Part of Human Biology” to which Joseph Carroll (2010) responded. Richerson then wrote a rejoinder (2010b). (Diana Kornbrot also participated in this conversation, but not in a way that bears on the issues that interest me.)

Both Richerson and Carroll are proponents of gene-culture coevolution – in fact, Richerson is one of the major developers of the model. Gene-culture evolution is grounded in the observation that cultural generation and transmission of traits from one generation to another can be more rapid than genetic origination and transmission. What gives the model its “teeth” is the further assertion that culture provides an environment for genetic evolution and can, indeed, influence it. Lactose tolerance is a standard example. While human infants can drink cows’ milk without difficulty, adults differ widely in their ability to do so. Adults from a population with a long history of dairy farming are much more likely to be able to digest cows milk than adults in populations lacking such traditions, suggesting that dairy-farming constitutes an environment that has influenced population biology (Laland and Brown 2002, 260-262).

While both Richerson and Carroll are proponents of gene-culture coevolution, they differ in how they think of the relationship between biology and culture. But, precisely because both are adherents of gene-culture coevolution, characterizing their difference is difficult. To re-purpose a metaphor from Clifford Geertz, who famously talked of thick description of culture (1973), Richerson clearly views culture as being thicker than Carroll does. On this I agree with Richerson. But I don’t believe that the gene-culture coevolution model contains adequate means for justifying that difference. Thus, their dialogue is beside the point.

Of leashes and harnesses

Richerson and Carroll explicate their difference in terms of constraint and autonomy. Early in his exposition Richerson introduces E.O. Wilson’s metaphor of biology as a leash on culture making it “a well controlled domesticate in service of the interests of genes,” a view that Carroll certainly holds. Near the end of his essay Richerson offers a slightly different metaphor, one that Plato once used to talk about the human soul:
Better to think of a team of horses. The gene-culture team is firmly harnessed together and jointly pulls the human evolutionary coach. No question of independence of genes or culture from each other. Every movement by one member of the team is felt by the other. The cultural horse is intrinsically faster and smarter and tends to act as the team leader. But alone her ability to pull the coach is strictly limited. The coach can move any distance only if the genetic horse is healthy and somehow induced to pull in the direction the cultural horse wants to go, which he may often not. His needs have to be well attended to if the team is going to function properly.
The leash by which biology exerts control over culture has given way to a harness though which the genes and culture are both connected to “the human evolutionary coach.” Note that Richerson has culture acting as “team leader.” That, as far as I can tell, is where he differs from Carroll, who does not, however, respond directly to this metaphor.

Carroll opens his response by noting that “Pete Richerson makes a case for the relative autonomy of ‘memes.’” Indeed, Richerson did talk of memes, though he shares much of Carroll’s uneasiness with the term itself and its popular usage. Carroll devotes most of his response to explaining why the notion of memes is doubtful. What bothers Carroll is Richerson’s sense that these memes are relatively autonomous. Note, however, that Carroll also explicitly affirms the notion that culture can influence the genes:
. . . culture can have major causal effects on form and function, as, for instance, cooking has done. Cooking is a cultural technology but has fundamentally altered the hominid gut and brain. Culture and genes have co-evolved, each influencing the other, with culture (cooking) producing a bigger brain, and the bigger brain producing yet more culture.
After all, Carroll too is an adherent of gene-culture coevolution.

And Richerson opens his response to Carroll responding, once again, in terms of autonomy and constraint:
I tried to anticipate Joe’s argument by explicitly disavowing the idea that culture is “autonomous.” Neither culture nor genes is autonomous. They are inextricably linked in the development of human behavior. Their evolution is intimately intertwined by gene-culture coevolution. Joe correctly points out that human culture can’t survive without genes. But neither can human genes exist without culture!
And we’re off. For what it’s worth, Richerson’s response to Carroll is longer (over 3300 words) than his original article (roughly 2600 words). But it’s not at all clear to me that he introduces any new ideas. Rather, it seems mostly to be an intensification and elaboration of his original essay. Richerson disagrees with Carroll, but he has no effective way of responding to him beyond, in effect, asserting: But I really really mean it.

Different metaphors

How, then, can we get beyond this impasse?

First, I don’t find this now standard imagery of autonomy and constraint very useful. Consider another metaphor: playing a game, such as chess. In this metaphor biology specifies the board, the pieces, and the legal moves while culture provides the strategies and tactics by which one plays the game. In this metaphor there’s no question that the player (culture) is constrained by the rules of the game (biology). That’s trivial; without those rules there wouldn’t be any game. It’s also quite clear than there’s more to playing an effective game of chess than simply knowing the rules. There are strategies and tactics that, while they must ultimately be expressed in legal moves, involve considerations of board configuration and power that are not at all specified in the rules of the game.

Much the same idea can be expressed by thinking of a child’s set of blocks. The blocks, along with physical law, are analogous to biology. Culture, then, could correspond to the various houses, boats, airplanes, and so forth, that the child builds with those blocks. The child’s moves are certainly constrained by “biology” – that is, by physical law – but the child nonetheless has considerable freedom (autonomy?) in what he constructs from those blocks. Note also that, in this metaphor, the child plays the role of designer, and the notion of design is an important one in thought about biological evolution, as it is in culture.

These metaphors give considerable scope to culture without implying any contravention of biological lawfulness. But they are only metaphors. How does one build a model of cultural process that has similar properties, that is, that gives considerable freedom (yes, freedom) to culture while at the same time respecting the claims of biology? That, of course, is a different matter, one I will take up in more detail in later posts.

Colin Martindale’s cultural selection

For now I want to look at The Clockwork Muse, in which Colin Martindale both presents a model of cultural change and offers considerable empirical evidence for that model. While explicitly referencing Darwin, Martindale has worked independently of the gene-culture coevolutionists. His object has been to work out an account of cultural selection that allows him to track and predict stylistic change: Why do certain artistic works find favor while others do not and why do those preferences change (evolve) over time?

Novelty is one factor in Martindale’s scheme. People seek the new. The trouble, of course, is that once one has sufficient experience of the new, it looses its capacity to excite. It has become old. Psychologists call this habituation, and it is a much-studied aspect of neural operation. How then, Martindale asks, can artists continually produce something new in the face of constant habituation in their audience? – not to mention themselves as well.

Following the ideas of Ernst Kris (a psychoanalyst) Martindale argues that the creative process involves alternation between inspiration and elaboration. During an inspiration phase one regresses toward a more primordial mode of being, more dream-like, in which one has access to relatively undifferentiated mental processes and objects. During an elaboration phase the undifferentiated contents are embodied in some medium using the devices and techniques appropriate to that medium. One can produce novel works, that is, works the overcome habituated responses, either by regressing to a more primordial level or by loosening one’s technical control over that primordial content, whatever it is, in the elaboration phase.

In particular, the two processes are independent of one another. Thus artists within a tradition can hold the level of elaboration constant while deepening the level of regression; this corresponds to a period of stylistic stasis. Alternatively, artists can keep the level of regression constant while loosening elaborative control, thus producing stylistic change. Taken together, these processes allow Martindale to model artistic change over periods of decades and centuries.

What is central to Martindale’s work is that he has been able to operationalize these ideas and thereby subject them to empirical investigation. Not only has he analyzed long runs of French and British and American poetry, bit he has also examined classic music, Gothic architecture, European painting, Japanese prints, and New England grave stones. In all cases he has found cyclic variations in form and content of the sort predicted by his theory.

Note that from Martindale’s point of view, one could imagine a large anonymous cultural fountain spewing forth aesthetic works of all kinds, with different levels of regressive content and stylistic elaboration of that content. It is the audience that decides which works it likes and it is those preferences that, in the long run, allow selected works to enter the canon. Thus when Martindale is tracking artistic change he is also indirectly tracking changes in the collective psyche.

Nothing in Martindale’s model contradictions biological reality. In fact, one of its starting points is the phenomenon of habituation, a neural process. Further, Martindale has a wide variety of empirical evidence, making it difficult to dismiss his model as mere speculation.

Where he differs from both Richerson and Carroll is in how he thinks about the impact of cultural processes on the genome: He doesn’t think about it at all. As far as I can tell, Martindale is not interested in whether or not art enhances the biological fitness of human populations. Without such populations, of course, there is no art. But, given populations of humans, how does art move among them? That is to say, human groups are the environment in which art thrives of dies. And the selective processes that Martindale investigates operate on works of art, not on human beings.

That, I believe, is the way we must think about cultural evolution. Taken in the large, culture is a biological adaptation that has allowed a tropical ape to move out of the tropics and inhabit every land-environment on earth – though our hold on the polar regions is rather tenuous. Given the physical survival of human groups, culture is also a domain with its own evolutionary dynamics, dynamics which are, in large measure, independent of biological evolution. That does not mean, however, that culture is independent of biology itself. Biology is the substrate in which culture lives. But it dictates the course of cultural evolution only so much as the laws of physics dictate the forms a child constructs from a set of blocks.


William Benzon (1996). Culture as an Evolutionary Arena. Journal of Social and Evolutionary Systems. Vol. 19, No. 4, pp. 321-362:

Joseph Carroll (2010). Response to Richerson. Politics and Culture. Issue 1:

Clifford Geertz (1973). The Interpretation of Cultures. Basic Books, Inc.

Kevin Laland and Gillian Brown (2002). Sense and Nonsense: Evolutionary Perspectives on Human Behavior. Oxford University Press, Inc.

Colin Martindale (1990). The Clockwork Muse: The Predictability of Artistic Change. Basic Books, Inc.

Peter J. Richerson (2010a). Culture is an Active Part of Biology, Politics and Culture. Issue 1:

Peter J. Richerson (2010a). Response of Joe Carroll’s Critique, Politics and Culture. Issue 1:


  1. I'll come back to this, but I've only read 2/3 so far. What strikes me about this question is that every important change on either side completely changes the ball game for the other. It's not a matter of making a single small or large adjustment, or a few, and going on from there. It means that any change gives the other side a whole new playing field and a whole new set of rules, and when the change occurs, the significance of the the change for the other partner is unknown and unknowable, not only to any possible observer, but in reality (i.e., there is an open future and more than one actually possible outcome and the different outcomes can be very significantly different -- Gould's contingency).

    And since both sides are dynamic already, and would be changing without any input from the other side, the game can be pretty wild.

  2. By "sides" you mean biology and culture? Note that culture can adjust more rapidly than biology.