Download Darwinism in Minds, Bodies and Brains

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
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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
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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.
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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
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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,
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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
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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
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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.
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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
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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. Authors attempt to
validate their own works using the aegis of The Origin of Species but, while relevant in some
instances, Darwin‟s ideas do not always provide a correct explanation that can account for all
observed phenomena.
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