Gabora's picture of the kick-starting of culture is reinterpreted and extended in order to make the subsequent internal evolutionary process credible. This is done by changing the unit of replication from a concept to a path consisting of a series of concepts, where each concept in the path has a tendency to cause the next to be recalled into the stream of thought. Mechanisms of selection and variation are suggested. The extended picture is shown to explain how an autocatalytic set of concepts might become a `world-view' in a more meaningful sense.
2. Gabora's scenario shows how a sufficient `density' of concepts in an associative memory structure (e.g. one with the structure of the Sparse Distributed Memory model) may allow the emergence of an autocatalytic process consisting of a self-triggering stream of thought. She suggests that an ability to abstract may have been a critical factor in crossing this density threshold. Once such a stream is established it then shapes and is shaped by the `world view' which is composed of the network of the concepts residing in an individual's memory.
3. The mutual interaction between the stream of thought and this network is characterised as an internal evolutionary process: the units are the concepts (which correspond to the points in an SDM architecture); the fitness of these is the frequency of recollection into the stream of thought (which is strongly correlated with its entrenchment in memory); replication is provided by the "correlation between consecutive memes; "selection is via "associations, drives, social pressures, affordances and limitations of the environment," and variation is a result of "sensory novelty, blending, expressive constraints." This process in turn allows an evolutionary process between individuals to develop. The internal and external processes are somewhat conflated in Gabora's account; here I will concentrate only on the internal process.
4. The characterisation of the internal process as evolutionary does not quite work since there is no reason why a successful concept (i.e. one that occurs in a stream of thought) should be more likely to be reselected via the replication mechanism suggested (the correlation between this concept and the next). In other words, there would be no correlation between this fitness and the probability of its replication. Furthermore, it is unclear exactly how the proposed mechanisms of variation will act on the concepts.
5. However, if one focuses upon paths consisting of a sequence of concepts, such that each item in the sequence is likely to invoke the next, then one can build a more obviously evolutionary picture. In contrast to a concept, a path has a mechanism by which, if it is selected as the contents of a stream of thought, it can increase the chance that it will be reselected - it can form a loop. It can do this either on its own or in conjunction with other paths. In this interpretation, each such path would be a meme - the unit upon which this evolutionary process acted.
6. The set of all such paths would be the memetic population. The fitness of each path would be the frequency with which it was recalled (and hence how entrenched it was in memory). There are several methods by which a path could encourage its own re-selection. First, it could form a loop so that it directly caused its own recall. Second, it could form a loop in conjunction with other paths so that its own selection caused the selection of other paths which had a propensity to cause it to be reselected. Third, it could be a path that tended to be recalled with certain stimuli from outside the organism, given that those stimuli where themselves frequent. These three possibilities are illustrated in figure 1 below.
FIGURE 1. SOME WAYS IN WHICH A PATH MAY CAUSE ITS OWN RECALL.
7. Variation could be introduced in a number of ways. First, there could be a simple addition of new concepts, so that an extra `point' is added to the path. Second, a `short-cut' could be discovered, cutting out a point. Third, there could be something similar to genetic crossover. This could occur when two paths pass through the same small locality, allowing a `derailment' from one path onto the other. Now the first section of the first path would lead on to the second part of the second path. These are illustrated in figure 2.
FIGURE 2. SOME WAYS IN WHICH VARIATION COULD BE INTRODUCED.
8. In this way we have all the requisites for an evolutionary process (Calvin 1997), but one where we would expect paths to be evolved rather than individual concepts. In all other respects it is compatible with the picture painted by Gabora.
9. The extended picture I have presented seems to have strong parallels with Adam's (1998) "synaptic Darwinism." They both posit an evolutionary process occurring to populations of pathways. However, his is at the neuronal level and is a general mechanism of learning which (if it turned out to be correct) would underlie learning in animals as well as humans. My picture represents a further evolutionary process between pathways of concepts which may (or may not) be implemented by a process of synaptic Darwinism.
10. My evolutionary picture also throws light on the question of why the mutual interaction of a dense set of concepts and a continuous stream of thought might result in a world-view. A world-view implies something more than just an autocatalytic set; for example, it is associated with pervasiveness and coherence. Pervasiveness is the property that whatever stimuli are encountered by the individual, there will be paths that will be triggered by it; there is no inherent reason why this would be true of an autocatalytic set. Coherence is the property that there will not be different sections of the population of paths that tend to be mutually exclusive; in Gabora's picture it is possible for two or more separate autocatalytic sets to emerge (although the probability of this could be a function of the connectiveness of the concepts). However, given the picture of evolving paths, one can see that if there were stimuli that did not trigger paths then one might expect paths to evolve to exploit this fact; and if there were separate and mutually exclusive parts of the network of paths, then one might expect one set eventually to win out over the other. In this way, once an autocatalytic process has occurred so as to stimulate a continuous stream of thought, an evolutionary process acting on paths will tend to develop this into a pervasive and coherent system -- one that might be meaningfully called a `world-view'.
11. Of course, the above picture is simplistic. There are many other organisational forces at work, including: a continuing autocatalytic process; a process of endorsing paths as to their adaptive value (i.e. learning about the environment); inter-individual memetic processes; the effect of the emotional and chemical state of the brain; and possibly meta-devices such as a mechanism of boredom to prevent small loops dominating.
12. Gabora's target article has showed us how functional models of the emergence of culture are possible, and even profitable to consider. This commentary has attempted to follow from her lead.
Calvin, W. H. (1997). The Six Essentials? Minimal Requirements for the Darwinian Bootstrapping of Quality. Journal of Memetics - Evolutionary Models of Information Transmission, 1. http://www.cpm.mmu.ac.uk/jom-emit/1997/vol1/calvin_wh.html
Gabora, L. (1998). Autocatalytic Closure in a Cognitive System. PSYCOLOQUY 9(67). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/ psyc.98.9.67.origin-culture.1.gabora http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?9.67
Adams, P. (1998). Hebb and Darwin. Journal of Theoretical Biology, 195:419-438.