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Darwinism in Minds, Bodies and Brains: Recent Research Perspectives A TSP Essay in the History and Philosophy of Science 2009 Ben Balzer Edward Talas Erin Doyle Isabelle Osborne Shannon Hayne 309227976 309207347 309258154 309200466 309228387 3rd Year Supervisor Caitlin Gillis Academic Supervisor Dr. Charles T. Wolfe “The publication of The Origin of Species marked an epoch in the development of the natural sciences... the combination of the very words origin and species embodied an intellectual revolt and introduced a new intellectual temper... In laying hands upon the sacred ark of absolute permanency... The Origin of Species introduced a mode of thinking that in the end was bound to transform the logic of knowledge, and hence the treatment of morals, politics, and religion.” (Dewey, 1910) Published in 1859, Charles Darwin‟s seminal work, The Origin of Species sparked an intellectual revolution. His argument and theory stood in stark contrast to the primarily religious explanation of how organisms came to be in their present form. Dewey‟s words reflect the significance of Darwin‟s publication, in that he challenged previously held conceptions about the origins of the species inhabiting the earth. Darwin‟s theory is that random variation in individuals creates traits that may benefit or hinder their „fitness‟ (that is, suitability) in relation to their environment, which will impact on their ability to survive. If these factors bestow a probability of greater reproductive success, the trait will, by Darwin‟s logic, propagate itself more widely through the population than any trait that will inhibit the capacity for survival or success of reproduction. Standing opposite to the widely believed creationist argument of its context, this concept has been revolutionary in science and history. Owing to the elegant simplicity, flexibility, explanatory potency and, to some extent, the revolutionary nature of Darwin‟s theory, many academic disciplines examine his work in a new context, applying it in their own fields of study in order to explain new phenomena. As a result, in some areas, the zealous championing of The Origin of Species and Darwinian Theory in general has led academics to pursue their studies in a Darwinian context. In some respects, Darwinian thought can be directly applied to their findings, whereas for many others, Darwin‟s ideas must be manipulated and over-extended to account for and accommodate results. As a result, the paradigm of Darwinian thought has been both applied and over-extended to a number of fields, including philosophy, neuroscience and medicine as will be considered in this essay. In a philosophical context, scholars have applied Darwinian thinking to reshape how we relate to the world, reconstructing our conceptions of Mind and meaning. In the field of neuroscience, Gerald Edelman has created a new theory of neuronal group selection, “Neural Darwinism,” extending Darwin‟s theory to the evolution of certain 2 paths and synapses in the brain. A number of authors, such as Nesse and Williams (1994) apply Darwin‟s theory to a several areas in medicine. This is an attempt to account for various medical phenomena though their application is not always perfect – in a number of cases appear to have extended Darwinism beyond its natural boundaries in order to explain observed trends. Philosophy The application of Darwinism to philosophical discourse has seen a radical rethinking of how we relate to the world. Specifically, Darwinian ideas suggest that Design can emerge from mere order without the need for a pre-existing complex causal force such as the Mind. Such a conclusion is espoused in Daniel Dennett‟s book Darwin’s Dangerous Idea. While Dennett‟s application of Darwinism has a degree of validity it will be shown that, due to the allencompassing extent of Dennett‟s argument, Dennett really only offers an extension of Darwinian theory, surpassing the boundaries of the original theory. In Darwin’s Dangerous Idea, Dennett recontextualises Darwinism to suggest it acts as a universal acid, reshaping the traditional structure of Western philosophy as it challenges the primacy of a Mind-first view of the universe. This view is most evident in John Locke‟s Essay Concerning Human Understanding as he argues, using the maxim Ex nihilio nihil fit, it is impossible to conceive that „bare incogitative Matter should produce a thinking intelligent Being‟(Locke, 1690, IV, x, 10). Therefore, Mind must come first, it cannot exist as the product of simpler, mindless phenomena. This view suggests a strict hierarchical structure intrinsic to pre-Darwinian world-views, summarized in Dennett‟s self-described Cosmic Pyramid: In Dennett‟s opinion, this pyramid acts more like a chandelier – a chain of being flowing from top to bottom (Dennett, 1995, p. 64). However, an application of Darwinian theory 3 breaks this continuity by suggesting that Design, the exploitation of Order for a specific purpose, can emerge from Order itself. This evolution is facilitated not by a higher level of the pyramid but by the random algorithmic processes of Natural Selection. Clearly, Designed objects imply a degree of research and development in their production – processes which are costly both in time and energy. Before Darwin only an intelligent artificer – an imaginary „skyhook‟ – could carry out the research and development implicit to the design process. Darwin saw this work distributed over a massive timeframe and efficiently carried out through the process of Natural Selection, which would conserve the successful design work previously accomplished. Hence, Natural Selection acts as a „crane‟, performing the „lifting work‟ in the vertical dimension of the Cosmic Pyramid from below and without the need for any miraculous „skyhook‟(Dennett, 1995, p. 75). It is Dennett‟s application of Darwinian theory that elucidates this process of Design from below, refuting the primacy of the Lockean Mind-first world-view and reshaping how we relate to the universe. To illuminate his alteration of the Cosmic Pyramid, it is best to examine Dennett‟s reevaluation of meaning through the lens of Darwinian processes. Not only is meaning a concept usually associated with Mind but it is implicit in Locke‟s Cosmic Pyramid. Hence, if it can be described through Darwinian processes it seemingly validates Dennett‟s claim of Darwinism as a universal acid. Within the course of his book, Dennett concludes that meaning is ultimately determined by selective forces which endorse a specific function. Such forces are in turn dependent on and determined by the environment meaning is created in (Dennett, 1995, p. 412). Dennett offers the example of a robot designed, through the process of research and development, as a survival machine for a cryogenically frozen individual. Dennett suggests the protected individual, who programmed the robot, is the source of all the derived meaning within the robot, limiting the possibility of any intrinsic original intentionality. However, through reactions to its environment, the robot takes on a degree of autonomy and therefore autonomous meaning. Dennett offers the robot as analogous to human beings, themselves essentially survival machines for their genetic code and the product of billions of years of research and development through algorithmic Darwinian processes. Therefore, our genes would be the original source of our intentionality and hence any meaning we could ever possibly contemplate (Dennett, 1995, p. 425). Nevertheless, Dennett still thinks we are able to develop autonomy through the impact of the cultural processes we imbibe. This shows all meaning – including human meaning – is dependent on function and is hence the product of naturally selective processes. 4 However, can this argument really be considered a valid extension of Darwinian theory? While there are some similarities, such as the focus on the agency of the environment, Dennett does little to explicate the specific processes of mutation and reproduction necessary to Darwinian theory. In many ways, Natural Selection is used as a descriptive, rather than explanatory, tool offering a neat framework on which Dennett‟s ideas can play out. Indeed, the specific mechanisms of the theory are discarded for an application of the algorithmic implications of Natural Selection. Furthermore, the focus on Natural Selection as a monolithic singularity is hardly concurrent with Darwin‟s original vision as he considered Natural Selection „the main, but not the exclusive means of modification‟ in nature (Darwin, 1985, p. 69). Hence, Dennett‟s use of Darwinism can really only be considered an extension of the original theory. Problems continue to arise with Dennett‟s use of Darwinism as his characterisation of theory as a universal acid is premised on a unification of genetic and cultural evolution in the single algorithmic process of Natural Selection. Dennett considers substrate neutrality – the idea that, when applied to various materials, the algorithm will work in the same manner – a necessary condition for the existence of an algorithm. However, Natural Selection, as applied by Dennett does not exhibit this substrate neutrality: Genetic evolution uses a Mendelian mechanism of inheritance to be effective while cultural evolution operates on a Lamarckian mechanism. However, these mechanisms cannot co-exist since the rapid time-scale of the Lamarckian process dominates the evolutionary process, pushing the gradual process of genetic evolution into insignificance (Gould, 1997, p. 49). Therefore, Darwinism cannot be considered this monolithic universal acid since memetic and genetic evolution are unable to united in the single algorithmic process of Natural Selection. Having established the misappropriation of Darwinism by Dennett we need to discern why the author has used Darwinian theory in the first place. Clearly, Dennett recontextualises Darwinism as a mechanism for persuasion, using the framework provided by this commonly accepted theory to propagate his own strictly atheist point of view. This has seen Darwin’s Dangerous Idea described as an exercise in contention, founded on Dennett‟s commitment to an ideology rather than a science (Goodheart, 2008, p. 25). Nevertheless, Dennett‟s use of Darwinian theory has some merits, specifically his analysis of the philosophical implications of the theory of Natural Selection. Dennett‟s exposition of the emergence of Design from Order certainly reshapes how we relate to the world. What remains problematic are his continuous, and often ideologically motivated, attempts to illuminate the universally 5 corrosive impact of Darwinism. Hence, Dennett, in recontextualising Darwinian theory to philosophical discourse, extends it beyond its logical boundaries and limits the validity of its application. Neuroscience As well as using Darwinian Theory to re-evaluate the philosophy of meaning and mind, many scholars have also attempted to apply Darwinism to the brain in an effort to better understand neural function. The concept of Neural Darwinism is essentially that proposed by Gerald Edelman in 1987, and encompasses the development of the brain and its functioning in terms of a selectionist process, where specific neural paths are selected and thus strengthened as a result of repeated use in behavioural experience. Each human brain begins its development with a huge complex of different neurons and synapses, in excess of what is required (Edelman, 1987). From very early development, even during embryo genesis, Edelman proposes that neurons send signals branching in many directions which generate great variability in the possible connection patterns. As some paths are repeatedly used, brought about by recurring behaviours, they are strengthened and become more efficient while others are instead weakened. This allows neurons to form “neuronal groups” (Edelman, 1987); essentially collections of hundreds to thousands of similar cells which mutually interact along the stronger and more efficient possible synaptic paths. In order to examine whether Edelman‟s controversial theory of “Neural Darwinism” really does reflect Darwin‟s own theories, one must consider the three specific tenets of Darwin‟s theory of evolution: random variation, selection and reproduction. The first of these, random variation, can be conceptually expanded to include Edelman‟s ideas, though it is not strictly a continuation of the ideas Darwin proposed (Plotkin, 1987). Darwin‟s theory relies on the idea of random variation occurring within a species; in this case this could be applied to random variation in neuronal paths. Edelman‟s theory, on the other hand, suggests that external influences in behavioural patterns and the environment induce variance within neural paths, implying that such variance is not in fact random. For example, Edelman‟s theory relates to human kind‟s apt ability for learning new concepts or tasks (Edelman, 1987). Moreover as this learning process or these tasks are repeated, ability improves. Edelman argues this is due to the repeated use of particular neuronal paths responsible for these tasks, 6 therefore increasing their synaptic strength and efficiency. So, the selection of the most efficient neural paths is not the product of random variation in neurons in the brain, but more of external influences. This conflicts with Darwin‟s theory which suggests evolution is the product of completely random variation, as opposed to beneficial variation in adapting to a new environment. The second tenet of Darwin‟s theory, selection, is more compatible with Edelman‟s theory. Edelman proposes that his theory is an extension of Darwinian Theory as paths and synapses become stronger and more efficient in a “survival of the fittest” selection-based process as neuronal groups compete for more neurons and the strongest paths survive and continue, leaving the other weaker “species” to die off (Barlow, 1987). This is essentially an extension of the reasonably recent understanding of the immune system which is also understood to operate using somatic selection as the enormous range of antibodies in the body are exposed to a foreign molecule leading to the selection and growth of the cells which carry the specific antibodies to fight the foreign species. Nevertheless, the main contention to this point is that Darwin‟s theory is based over many generations of a species that might over a large time period lead to evolution in the whole species. Conversely, neural „evolution‟ is concentrated over a somatic time period; hence Edelman discusses the evolution of an individual‟s brain in their own life (Plotkin, 1987). While the principles are essentially the same as Darwin‟s theory, there is a clear manipulation of his ideas in reducing his theory from many generations to just one life-span. The superficial similarities between Edelman‟s theory, and that of Darwin‟s Natural Selection are apparent in variation and elimination, however this is where the correspondence ends. A consideration of replication and reproduction of a species is crucial in considering the evolution of that species, and the surviving characteristics. It is the application of this element in Edelman‟s theory which, despite being the most significant, is the least plausible. Once the elimination, or „dying out‟, of neural paths occurs, there is no further repetition, or replication of neurons to carry on the ability to „select‟ this most efficient synaptic path. It may therefore be said that „learning‟ is not the formation of neural paths, but merely a process of elimination of already existing ones. The most noteworthy and substantial analysis and criticism of this lack of reproduction was by Crick (1989), because for a „natural selection‟ theory of evolution, heredity is indispensible (Fernando, C., Karishma, K., Szathmary, E., 2008). One must however note that it is not being argued that no more neural paths are being formed, even as adults paths are created, but this observation doesn‟t fit into 7 the „selectionist‟ theory (Quartz, S., Sejnowski, T., 1997). Therefore, Neural Darwinism would be better named “Neural Edelmanism”, since the plausibility of the theory‟s connection to Darwin‟s theory is stretched when reproduction is considered (Crick, 1989). Instead of completely random variation, the concept of „Neural Darwinsim‟ centres on an excess of neurons and neuronal paths in the brain, in which variation occurs due to behavioural experience during development. Due to repetitive use, certain neuronal paths and synaptic connections become stronger, others weaker, leading to a „survival of the fittest‟ phenomenon, as neuronal groups compete for neurons, and unused paths „die off‟. There is no sense of reproduction or inheritance however, a critical element to Darwinist thought. It does provide an interesting theory for one to consider regarding brain functioning, whether concurrent with Darwin‟s Theory or not. Medicine An examination of Darwin‟s theory in the field of medicine similarly sees authors attempting to apply Darwinian Theory in order to explain and understand medical phenomena. Unlike neuroscience, however, it presents us with a dichotomy: while it is clear that there are examples where medicine follows strictly Darwinian principles, there are several crucial examples that demonstrate a manipulation of Darwin‟s theories in an effort to explain observed phenomena. While cases such as sickle-cell anaemia and Type One diabetes have been clearly naturally selected as favourable characteristics in particular environments (Nesse et al. 2007 p.28), the issues of immunity and human skeletal anatomy provide counter-claims to the assertion that medicine needs evolution to satisfactorily account for health issues faced by humanity (Nesse et al. 2007). Given the gamut of diseases and conditions that provide cases for both the application and extension of Darwinian Theory, there is considerable depth in this subject area. This section will examine the application and extension of Darwinian Theory using three key examples: how it has been applied to explain the relationship between sickle cell anaemia and malaria, and its extension in considering the immune system and human skeletal design. Sickle-cell Anaemia is a recessive genetic disease in which the morphology of red blood cells is affected, thus impeding the oxygen-carrying capacity of an individual. Specific combinations of alleles determine the extent to which the individual is affected – individuals homozygous for the sickling allele experience serious health complications, whereas in 8 heterozygous individuals mild health complications are present but there is also an increased resistance to malaria (Nesse et al. 1994, p.99). The highest rates of individuals heterozygous for sickling allele are found in sub-Saharan Africa, the same region that boasts one of the largest populations of Anopheles gambiae, the mosquito that carries and transmits malaria (Moalem, 2007, p.88). Owing to the fact that sickle-cell anaemia protects against the development of malaria in those carrying the gene, the application of Darwinian Theory provides an explanation for the regional prevalence of this allele. Darwin‟s theory of evolution argues that in any population there is selective pressure. As a result of this, better-adapted individuals tend to survive and reproduce while less welladapted individuals die and do not pass on their genetic information. In sub-Saharan Africa, where the rate of malaria infection is high, the better-adapted individuals are clearly those that possess some resistance to the disease; that is, individuals heterozygous for the sickling allele. These individuals are therefore more likely to survive and pass on their genes to the next generation, and thus the allele has been found in high frequencies through a number of generations due to the selective advantage it provides. This also explains why high rates of sickle-cell anaemia in developed cities are not observed (where there are relatively lower populations of mosquitoes), as the gene is not selectively advantageous in these cases. However, an application of Darwinian Theory to a disadvantageous allele such as this would normally predict that it would be bred out of the population. In sub-Saharan Africa, however, 40% of the population possess the sickling allele (Moalem, 2007, p.88). This is an example of a balanced polymorphism – that is, where two different traits give individuals the same fitness to survive (Dowdeswell, 1984, p.84-85). Here, the selective advantages of having normal red blood cells and being heterozygous for the sickling allele are balanced, as having normal cells allows an individual to function efficiently whereas having mildly sickled cells protects the individual against malaria. Therefore, both forms of the gene remain in the population, as their selective advantages are balanced (Dowdeswell, 1984, p.85). In spite of this; balanced polymorphism was never an original component of Darwin‟s theory. This example, therefore, cannot be an exact application of Darwinian evolution, as it deals with subjects that Darwin never thought to consider. Rather, it is an example of how modern medicine has been able to add to Darwin‟s theory in order to apply it to what is a clear example of natural selection. Here, it is still an application – albeit an imperfect one. 9 On the other hand, when relating Darwinian thought to cases such as human immunity and the skeletal system, it is clear that Darwin‟s original writings have been manipulated to provide an explanation for such phenomena that allows authors such as Nesse and Williams (1994) to maintain that Darwinian evolution is a fundamental force in medicine and the study thereof. A variety of studies have been undertaken in the field of immunology that indicate that there may be a far more complex mechanism behind the human immune system than merely Darwinist selection. Gorczynski‟s (1981) study on immunity indicated some level of inheritability of immune tolerance. Inheritance of acquired traits is a concept more reflective of Lamarckian evolution, a theory which had faced much derision in the scientific community, until Gorczynski‟s study, though there is some dispute as to the replicability of his data (Hasek et al., 1985, p.38), despite Müllbacher‟s (1983) results displaying similar trends. More recently, studies on animals, (Silverstein (2009); Iwakoshi (2001)), provided further evidence for Gorczynski‟s findings. The realisation that immunity may be inheritable, at least to an extent, has significant implications for the medical community, as it indicates that Darwinian Theory is not necessarily the sole explanation for medical phenomena. Darwin‟s name is used to give validity to certain claims, and given the elegance and flexibility of his evolutionary theory; it is more attractive to apply his theory, even if it does not necessarily provide the best explanation for reported phenomena. In this way, it is apparent that Darwinism is, to some extent, forcibly extended in areas of medicine that require much deeper inquiry. Darwinian Theory is manipulated in respect to the skeletal design of man. Charles Darwin, in The Descent of Man (1877), spoke of the human skeletal system, especially the spinal column as having evolved in a perfect manner to support the skull and allow upright posture and bipedalism (p.57). It can be argued that this evolution is actually a “trade-off” (Nesse, 1994, p.131) or compromise, with multiple imperfections leading to lower back pain, greater susceptibility to injuries in joints such as ankles and knees, and even so far as to claim that digestive system blockages, haemorrhoids and hernias are a result of our evolutionary compromise between bipedalism and the skeletal system (Nesse et al., 1994, p.131). While the arguments made by such authors (Nesse, 1994; Tobias, 1982) may be objectively true, their arguments deviate from what Darwin himself wrote, though they attempt to explain such flaws as being under the aegis of Darwinian evolution. The evolution of the human body is not disputed, yet the explanation of and opinions on it is. Authors insinuate that their work reflects Darwinian Theory perfectly, yet they contradict the texts they claim to champion. In 10 this sense, one may see that Darwinian Theory, when considering immunity and the skeletal system, is over-extended and manipulated by modern science. Conclusion The Origin of Species has caused continual dialogue and debate between scholars since its publication in 1859. Darwin‟s description of a mechanism for the origins of life that did not necessitate an intelligent or deliberate design led to controversy in many circles, to the extent that Darwinian evolution is a topic of debate even today. With the advent of genetics and the DNA theory since Darwin‟s original publication, such concepts have been accommodated into his original biology-based argument, owing to its flexibility. In light of this, many modern scientists have also used Darwinian Theory in an attempt to explain their own findings in a multitude of fields, including philosophy, neuroscience and medicine. In philosophy, Darwinian Theory has offered a unique descriptive framework by which to reinforce particular ideologies, not as an explanatory model like its valid application implies. In Neuroscience, Edelman has attempted to extend Darwinian Theory to encompass his own theories about neuronal groups in the brain entitled “Neural Darwinism.” However, he has merely taken the general essence of Darwinian Idea and over-extended it to the field of neurosciences, lending further credibility to his own concepts regardless of whether the theory he proposes can actually be linked to Darwinism. A number of authors have applied Darwin‟s theory to medicine, attempting to explain why the array of diseases and conditions present in the population continue to exist. This is particularly effective when explaining the development and existence of certain diseases, though there are significant cases which do not conform to Darwinian evolutionary principles. Despite this, an over-zealous and incorrect use of Darwinian Theory, manipulated to fit the results given, continues in many academic fields. It is because of the inherent simplicity and flexibility of Darwinian Theory that such applications can be made. However, it is over-extended in many academic fields and utilised as a convenient framework upon which authors can base their ideas. 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