Thursday, November 29, 2007

The eight-fold structure of evolutionary biology/ cultural evolution

Regulars readers of this blog will know that I am sold on the eight-fold developmental theory that assumes that there are eight stages of development/evolution of any feature and I have explored this extensively. Five of these lower stages are at a different level and the upper 3 at a different level explain the development of the same phenomenon. for a quick summary and links to my eight-fold fascination please see this the first paragraph of this post. So it is no surprise that I was fascinated when I discovered that evolutionary biology is conceptualized as eight subjects or methods of inquiry and they also follow a 5 +3 pattern with 5 lower levels referring to within species evolution and the last 3 referring to between species evolution. This structure of evolutionary biology I discovered via a fascinating artcile that tries to find parallels between cultural evolution and biological evolution. The article is by Mesoudi et al (2006) and I will be heavily quoting from that paper.

First a very beautiful figure that shows the structure of evolutionary biology and draws parallels to cultural evolution. Explanation of figure follows.

The left hand side of Figure 1 illustrates the overall structure of evolutionary biology, as described by Futuyma (1998, pp. 12-14) in what is, perhaps, the most widely used undergraduate textbook in the field. The study of biological macroevolution deals with change at or above the species level, while biological microevolution concerns changes within populations of a single species. The former comprises systematics, paleobiology and biogeography, while the latter involves population genetics (theoretical, experimental and field-based), evolutionary ecology and molecular genetics. In Sections 2 and 3 we examine each of the sub-disciplines of evolutionary biology in turn, first outlining their general methods then briefly describing examples of recent studies to illustrate how those methods are applied and the kind of results they yield. This is followed in each case by a discussion of existing analogous or equivalent methods within the social sciences regarding human culture, again describing recent key studies. These cultural disciplines, and the way in which they map onto the structure of evolutionary biology, are illustrated on the right hand side of Figure 1. While there may be no obvious precedent for two distinct fields to exhibit the same internal structure, the similarity of underlying processes leads us to expect a correspondence.

Now let me come to the central theme of the paper that cultural evolution has parallels in evolutionary biology and the sub disciplines and methodologies from one can inform the other.

Parallels or analogies between biological and cultural evolution have been noted by a number of eminent figures from diverse fields of study.The implication of this growing body of theory is that culture exhibits key Darwinian evolutionary properties. If this is accepted, it follows that the same tools, methods and approaches that are used to study biological evolution may productively be applied to the study of human culture, and furthermore that the structure of a science of cultural evolution should broadly resemble the structure of evolutionary biology. In the present paper we attempt to make this comparison explicit, by examining the different approaches and methods used by evolutionary biologists and assessing whether there is an existing corresponding approach or method in the study of cultural evolution. Where such an existing correspondence is not found, we explore whether there is the potential to develop one. We also explore potential differences between biological and cultural evolution.

They also elaborate on benefits of the evolutionary eight-fold approach.

Second, and particularly relevant to this article, the theory of evolution encompasses and integrates a multitude of diverse sub-disciplines within biology, from behavioural ecology to paleobiology to genetics, with each sub-discipline stimulating and contributing to several others (see Mayr, 1982 for further details of this 'evolutionary synthesis'). The social sciences, in contrast, have no such general synthesising framework, and the greater part of disciplines such as cultural anthropology, archaeology, psychology, economics, sociology and history remain relatively insular and isolated, both from each other and from the biological and physical sciences. Adopting an evolutionary framework can potentially serve to highlight how these disciplines are, in fact, studying complementary aspects of the same problems, and emphasise how multiple and multidisciplinary approaches to these problems are not only possible but necessary for their full exposition. At present, many of the individual studies considered below are the result of independent developments at the fringes of separate fields of study. Placing these disparate studies side-by-side within a broader evolutionary framework, as is done here, will hopefully contribute towards creating a coherent unified movement and bring evolutionary analyses of cultural phenomena into the mainstream. They then go on and explore each of the subdivision in detail and draw parallels to cultural evolution and show how methods of evolutionary biology when applied to culture have helped solve many problems there.

They also analyze psychology as equivalent to experimental population genetics. Reproducing the relevant sections below:

One parallel with this work lies in laboratory based psychological experiments simulating cultural transmission. Where population genetic experiments simulate biological evolution by studying the transmission of genetic information from generation to generation through the reproduction of individuals, psychological experiments can potentially simulate cultural evolution by studying the transmission of cultural information (e.g. texts or behavioural rules) from one individual to another through social learning.

One method for simulating cultural evolution was developed by Gerard, Kluckhohn and Rapoport (1956) and Jacobs and Campbell (1961). A norm or bias is established in a group of participants, usually by using confederates, and one by one these participants are replaced with new, untrained participants. The degree to which the norm or bias remains in the group after all of the original group members have been replaced represents a measure of its tansmission to the new members.

For example, Baum et al. (2004) studied the transmission of traditions using a task in which participants received financial rewards for solving anagrams. Groups of individuals could choose to solve an anagram printed on either red or blue card: the red anagrams gave a small immediate payment, while the blue anagrams gave a larger payoff but were followed by a ‘time-out’ during which no anagrams could be solved. By manipulating the length of this time-out, the experimenters were able to determine which of the two anagrams gave the highest overall payoff (i.e. where the blue time-out was short, blue was optimal, and where the blue time-out was long, red was optimal). Every 12 minutes one member of the group was replaced with a new participant. It was found that traditions of the optimal choice emerged under each experimental condition, with existing group members instructing new members in this optimal tradition by transmitting information about payoffs and timeouts, or through

Key similarities exist between this study and the experimental simulations of natural selection described above. In Kennington et al.’s (2003) study with Drosophila, where the experimentally determined conditions of low humidity favoured small body size, smaller individuals out-reproduced larger individuals. Hence genetic information determining ‘small body size’ was more likely to be transmitted to the next generation through biological reproduction, and the average body size of the population became gradually smaller. In Baum et al.’s (2004) study, where the experimentally determined conditions favoured red anagrams (when the blue time-out was relatively long), choosing red anagrams gave a larger payoff to the participants. Hence the behavioural rule ‘choose red’ was more likely to be transmitted to the new participants through cultural transmission, and the overall frequency of choosing red
gradually increased.

Baum et al.’s (2004) method could easily be adapted to study the cultural evolution of attitudes or beliefs. Groups of participants could be asked to discuss a contentious issue, then every generation the participant with the most extreme opinion in a certain direction removed and replaced with a random participant. After a number of generations the group should hold more extreme views (in the opposite direction to those of the removed participants) than average members of the larger population.

Finally they discuss psychology in relation to evolutionary ecology and neursocience / memetics in relation to molecular biology.

While genetic information is represented in sequences of DNA molecules, cultural information is represented primarily in the brain. Viewing culture as comprised of discrete units of information, or memes, can potentially make a complex system theoretically and empirically tractable, in the same way as the gene concept advanced biologists’ understanding of biological evolution. Although memes can be characterised as vague entities with flexible and fuzzy boundaries, so can the modern concept of the gene. It should be remembered that there was at least 50 years of productive investigation into biological microevolution before the molecular basis of genetic inheritance was determined, and even now it is only partly understood.
A deeper understanding of the neural and molecular basis of culturally acquired information must rely on technological advances in, for example, neuroimaging techniques. However, we should also reserve the possibility that the same cultural information is specified by different neural substrates in different brains, severely limiting such methods for studying cultural transmission. In this case there may be no cultural equivalent to molecular biology, although models and methods examining cultural transmission at the behavioural and cognitive levels can still provide important insights.

To me all this seems very interesting and I end with their conclusion:

The evidence discussed in this paper suggests that much potential exists for a comprehensive science of cultural evolution with broadly the same structure as the science of biological evolution, as outlined in Figure 1. This potential is already being realised for the study of cultural macroevolution and the mathematical modelling of cultural microevolution, with methods developed within evolutionary biology, such as phylogenetic analyses and population genetic models, being applied to cultural data. A number of opportunities exist for psychologists, sociologists and experimental economists to adopt the experimental methods and tools developed in population genetics to simulate cultural microevolution, and detect cultural evolution ‘in the wild’. Finally, the study of the neural basis of cultural transmission is seemingly dependent on advances in new technologies that should reveal how culturally acquired information is represented in the brain.

In short, we submit that the argument that culture exhibits a number of key Darwinian
properties is well-supported, and advocate taking advantage of this in order to use evolutionary biology as a model for integrating a multitude of separate approaches within the social sciences, and, where appropriate, borrowing some of the methods developed by evolutionary biologists to solve similar problems. Putting disparate studies from presently unconnected disciplines together into a broad evolutionary context adds value to each of the individual studies, because it illustrates that the degree of progress in this area is far more impressive than hitherto conceived. We suggest that these studies can now be said to be aligned within a unified ‘movement’, and that if this Darwinian evolutionary movement could be better co-ordinated, a more persuasive and important direction could be put on much work in the social sciences.

Hat tip: Natural Rationality

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