For more than ten years, I have intended to submit an article to Behavioral and Brain Sciences on the power of preadaptation and access. The excellent article by Anderson on neural reuse provides strong evidence for preadaptation and access, and I jump at this opportunity.
Preadaptation is a basic principle in twentieth-century evolutionary biology (Bock Reference Bock1959; Mayr Reference Mayr and Tax1960). As Ernst Mayr points out: “The emergence of new structures is normally due to the acquisition of a new function by an existing structure . . . the resulting ‘new’ structure is merely a modification of a preceding structure” (Mayr Reference Mayr and Tax1960, p. 377). The basic idea is that something that evolved for one function is used for another. Occasionally the original structure is not itself an adapted entity, falling under the broader category of exaptation (Buss et al. Reference Buss, Haselton, Shackleford, Bleske and Wakefield1998; Gould Reference Gould1991; Gould & Vrba Reference Gould and Vrba1982). The human brain is surely a preadaptation: a very large processing system selected to solve a wide range of problems, then adapted to solve (or create!) problems other than those for which it was originally selected.
In 1976, in response to the view that learning was accomplished by a few general-purpose and domain-insensitive mechanisms, I put forth some ideas in a paper entitled “The Evolution of Intelligence and Access to the Cognitive Unconscious,” ideas that were related to preadaptation and to the issues raised by Anderson (Rozin Reference Rozin, Sprague and Epstein1976). Below, I list a few points made in this 1976 paper and in some subsequent work (Rozin Reference Rozin, Kahneman, Diener and Schwarz1999; Reference Rozin, Carruthers, Laurence and Stich2006) that anticipate some of the later findings and/or suggest directions for future work.
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1. The building blocks for innovations in evolution, and particularly the brain, are adaptive specializations (called modules by Fodor) which are circuits or structures specifically dedicated to performing a specific function. These can be considered preadaptations.
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2. In the course of evolution, these modules may be accessed by other systems, and thus acquire a new function. The original function may remain (e.g., shared circuitry – neural reuse), or the original function may disappear.
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3. Accessibility is a dimension, varying from a dedicated module at one extreme to attainment of consciousness, which usually means total access to all systems. The brain (mind) is neither totally modular nor totally a general processor. It is both and everything in between.
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4. A parallel process of increasing access occurs in development (e.g., Piaget's décalage), and an inversion of this process is associated with degeneration of the nervous system.
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5. Alphabetic writing and reading presumes some level of access (or even “insight”) into the fact that “bat” has three sounds. This can be framed as gaining access to the phonological processing “module.”
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6. In addition to the idea of reuse, there is an alternate preadaptive pathway (Rozin Reference Rozin, Sprague and Epstein1976): that is, to reproduce the genetic/developmental plan for a particular neural circuitry in another part of the brain. This presumably happened, for example, with multiple topographic representations of space in different visual areas of the brain.
The impressive recent data supporting the idea of a literally embodied mind are an instance of preadaptation and access, in the use of sensory and motor cortical structures to represent “higher” functions.
The framework I present highlights the critical developmental-evolutionary problem with this whole class of models. As formulated by Mayr, the problem is: “How can an entirely new structure be gradually acquired when the incipient structure has no selective advantage until it has reached a considerable size and complexity?” (Mayr Reference Mayr and Tax1960, p. 350). How do we get from a photosensitive cell to an eye, from a fin to a limb, from a jaw articulation to middle ear bones? Many of the imaginable intermediate stages are not adaptive. In terms of the reuse (as opposed to duplicate circuitry) model, physical contact is necessary between a brain area whose function could be improved and the other circuitry that could enhance its function, in order for selection pressure to operate. Getting closer is not more adaptive; it is contact that is needed. One must identify the selective force that leads to contact, as demonstrated beautifully by Bock (Reference Bock1959) in his analysis of how an enlarging muscle insertion point on the mandible of a particular bird species becomes a jaw articulation after it contacts the skull. There is no doubt that some type of contact has been established in many important examples of preadaptation in evolution, as, for example, the invasion of land by aquatic vertebrates. There are examples of preadaptation where the new adaptation replaces the old (reptile jaw articulation to middle ear bones) and others more like reuse, where a structure maintains its old function and acquires a new one (such as the human tongue functioning both in ingestion and in the articulation of speech sounds).
Brain anatomy, and developmental constraints, probably make it difficult to physically co-opt circuits that are not in close proximity. One possibility, implied by some of the work of Dehaene and Cohen (Reference Dehaene and Cohen2007), is that expansion of a particular area of the brain brings it into contact with neural tissue that can improve its function by integrating this circuitry.
Natural selection is powerful when there is transmission. But it can only act on the available variants, and it can be trapped by local optima and the necessity to bridge maladaptive intermediate phases. And here is where something wonderful comes in to speed up and expand the process immensely. Culture! Preadaptation, however impressive in biological evolution, is massively important in cultural evolution, because the variants can be generated purposively, and there is tolerance for maladaptive intermediate stages, motivated by the desire to reach a goal. The extraordinary power and speed of cultural evolution is well documented (GirifalcoReference Girifalco1991; Newson et al. Reference Newson, Richerson, Boyd, Kitayama and Cohen2007). Natural selection can work without constraints! The results are computers, memory storage systems that evolve by the year, Mozart symphonies, and the like. I am astonished that evolutionary psychologists are not excited by the application of the principle of natural selection to the study of cultural evolution, given that they can watch it happen (Rozin, in press). I was excited to learn from Anderson that Dehaene and Cohen (Reference Dehaene and Cohen2007) have been examining how processes like access can occur in the developing brain under the selective guidance of cultural selection. I think this is what I was talking about in 1976 as accessibility in development and in cultural evolution (Rozin Reference Rozin, Carruthers, Laurence and Stich2006). But we still have to figure out how Mother Nature built such an extraordinary creature as the human before intentional cultural actions made abilities and artifacts available as preadaptations.
You have
Access
For more than ten years, I have intended to submit an article to Behavioral and Brain Sciences on the power of preadaptation and access. The excellent article by Anderson on neural reuse provides strong evidence for preadaptation and access, and I jump at this opportunity.
Preadaptation is a basic principle in twentieth-century evolutionary biology (Bock Reference Bock1959; Mayr Reference Mayr and Tax1960). As Ernst Mayr points out: “The emergence of new structures is normally due to the acquisition of a new function by an existing structure . . . the resulting ‘new’ structure is merely a modification of a preceding structure” (Mayr Reference Mayr and Tax1960, p. 377). The basic idea is that something that evolved for one function is used for another. Occasionally the original structure is not itself an adapted entity, falling under the broader category of exaptation (Buss et al. Reference Buss, Haselton, Shackleford, Bleske and Wakefield1998; Gould Reference Gould1991; Gould & Vrba Reference Gould and Vrba1982). The human brain is surely a preadaptation: a very large processing system selected to solve a wide range of problems, then adapted to solve (or create!) problems other than those for which it was originally selected.
In 1976, in response to the view that learning was accomplished by a few general-purpose and domain-insensitive mechanisms, I put forth some ideas in a paper entitled “The Evolution of Intelligence and Access to the Cognitive Unconscious,” ideas that were related to preadaptation and to the issues raised by Anderson (Rozin Reference Rozin, Sprague and Epstein1976). Below, I list a few points made in this 1976 paper and in some subsequent work (Rozin Reference Rozin, Kahneman, Diener and Schwarz1999; Reference Rozin, Carruthers, Laurence and Stich2006) that anticipate some of the later findings and/or suggest directions for future work.
1. The building blocks for innovations in evolution, and particularly the brain, are adaptive specializations (called modules by Fodor) which are circuits or structures specifically dedicated to performing a specific function. These can be considered preadaptations.
2. In the course of evolution, these modules may be accessed by other systems, and thus acquire a new function. The original function may remain (e.g., shared circuitry – neural reuse), or the original function may disappear.
3. Accessibility is a dimension, varying from a dedicated module at one extreme to attainment of consciousness, which usually means total access to all systems. The brain (mind) is neither totally modular nor totally a general processor. It is both and everything in between.
4. A parallel process of increasing access occurs in development (e.g., Piaget's décalage), and an inversion of this process is associated with degeneration of the nervous system.
5. Alphabetic writing and reading presumes some level of access (or even “insight”) into the fact that “bat” has three sounds. This can be framed as gaining access to the phonological processing “module.”
6. In addition to the idea of reuse, there is an alternate preadaptive pathway (Rozin Reference Rozin, Sprague and Epstein1976): that is, to reproduce the genetic/developmental plan for a particular neural circuitry in another part of the brain. This presumably happened, for example, with multiple topographic representations of space in different visual areas of the brain.
The impressive recent data supporting the idea of a literally embodied mind are an instance of preadaptation and access, in the use of sensory and motor cortical structures to represent “higher” functions.
The framework I present highlights the critical developmental-evolutionary problem with this whole class of models. As formulated by Mayr, the problem is: “How can an entirely new structure be gradually acquired when the incipient structure has no selective advantage until it has reached a considerable size and complexity?” (Mayr Reference Mayr and Tax1960, p. 350). How do we get from a photosensitive cell to an eye, from a fin to a limb, from a jaw articulation to middle ear bones? Many of the imaginable intermediate stages are not adaptive. In terms of the reuse (as opposed to duplicate circuitry) model, physical contact is necessary between a brain area whose function could be improved and the other circuitry that could enhance its function, in order for selection pressure to operate. Getting closer is not more adaptive; it is contact that is needed. One must identify the selective force that leads to contact, as demonstrated beautifully by Bock (Reference Bock1959) in his analysis of how an enlarging muscle insertion point on the mandible of a particular bird species becomes a jaw articulation after it contacts the skull. There is no doubt that some type of contact has been established in many important examples of preadaptation in evolution, as, for example, the invasion of land by aquatic vertebrates. There are examples of preadaptation where the new adaptation replaces the old (reptile jaw articulation to middle ear bones) and others more like reuse, where a structure maintains its old function and acquires a new one (such as the human tongue functioning both in ingestion and in the articulation of speech sounds).
Brain anatomy, and developmental constraints, probably make it difficult to physically co-opt circuits that are not in close proximity. One possibility, implied by some of the work of Dehaene and Cohen (Reference Dehaene and Cohen2007), is that expansion of a particular area of the brain brings it into contact with neural tissue that can improve its function by integrating this circuitry.
Natural selection is powerful when there is transmission. But it can only act on the available variants, and it can be trapped by local optima and the necessity to bridge maladaptive intermediate phases. And here is where something wonderful comes in to speed up and expand the process immensely. Culture! Preadaptation, however impressive in biological evolution, is massively important in cultural evolution, because the variants can be generated purposively, and there is tolerance for maladaptive intermediate stages, motivated by the desire to reach a goal. The extraordinary power and speed of cultural evolution is well documented (GirifalcoReference Girifalco1991; Newson et al. Reference Newson, Richerson, Boyd, Kitayama and Cohen2007). Natural selection can work without constraints! The results are computers, memory storage systems that evolve by the year, Mozart symphonies, and the like. I am astonished that evolutionary psychologists are not excited by the application of the principle of natural selection to the study of cultural evolution, given that they can watch it happen (Rozin, in press). I was excited to learn from Anderson that Dehaene and Cohen (Reference Dehaene and Cohen2007) have been examining how processes like access can occur in the developing brain under the selective guidance of cultural selection. I think this is what I was talking about in 1976 as accessibility in development and in cultural evolution (Rozin Reference Rozin, Carruthers, Laurence and Stich2006). But we still have to figure out how Mother Nature built such an extraordinary creature as the human before intentional cultural actions made abilities and artifacts available as preadaptations.