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Analysis and critique of the concept of Natural Selection (and of the
Darwinian theory of evolution) in respect to its suitability as part of
Modernism's origination myth, as well as of its ability to explain organic
evolution (August 1999; [updated August 2002] )
S.N.
Salthe
website: http://www.nbi.dk/~natphil/salthe/index.html
I would point out here that, despite the widespread conflation of the
concept of evolution with the Darwinian theory to explain it (we now begin
to hear phrases like "natural evolution", which tends to forge a
conflation with natural selection), the following remarks apply strictly
to the latter. Concerning this theory, I believe that we might question
(or at least note) the following:
(1) Its derivation from classical capitalist economic theory
This is not just ad hominem because we live in a sociopolitical system
that itself derives from the classical capitalist ones. This throws
suspicion on the theory, in that it may be widely supported (as it is) by
folks in many fields of inquiry just because it fits so intelligibly
within the world we have created around us. This obscures questions of its
"truth", so that this becomes undecidable under philosophical inspection.
As will be explained in (8), below, the values implied by this theory
derive from its privileging of short term gain, expedience and
opportunism, which are coherent with capitalism.
(2)Along these lines, it ought to be noted that the theory of
natural selection is itself very fit in the conceptual world generated by
our culture.
Being a theory that works on the principle of competition, it is itself
very capable of outcompeting theories native to various fields (in this
way it is self-referential). For example, in the field of immunology, it
outcompeted instructionist theories. How necessary was this replacement?
Yes, the selectionist theory works there, but are we sure that (in a
different conceptual environment) an instructionist theory could not be
constructed that would work as well? ("Work" here means being fruitful in
the pursuit of pragmatic knowledge.) If we have a choice of several kinds
of theories, all of which are adequate to drive investigation in some
discourse, certainly the one that best fits into our current discursive
environment will be chosen. Once again, its general truth is suspect.
(3) Its material emptiness.
This is demonstrated by the fact that it has jumped from field to field
in the last decades. Formally, all that are required to get natural
selection (Lewontin) are (a) preexisting variability in (b) fittingness to
an environment, when any of the variants (c) can be propagated by some
system of replication with equal facility and cost. (The degree of
differential propagation is referred to as fitness.)
Materially empty theories are theories of anything.
When we couple this with (1) and (2) above, we see the possibility of a
Borgesian theory that cannot be resisted, or, at least, could be plausible
in any field. Of course this may not make any
difference with respect to the social function of science -- which is to
predict, or learn to control, natural processes. It is possible that, in
the face of an indefinitely complex and generative world, this function
could be carried out with any number of different, even incompatible
theories. The point is to get the job done, not to understand truly. [I
refer to natural selection's practical usefulness to society in (4,b).]
If this theory is materially empty, we might wish
to know what kind of theory it actually is. I would say that it is a
semiotic theory -- that is, a theory of meaning. Selection is a principle
of matching between configurations, where one configuration represents,
reflects, or is a sign of, another. Ultimately, meaning, in its biological
application, is held to be stored in DNA sequences and configurations. So
natural selection is about meaning, and meaning is held in informational
configurations, not in material dynamics (Pattee).
(4) Its social function in the anticipation and control of Nature
has, until recently, been vestigial. Nevertheless it grew like topsy. (a)
Let us ask why. And then (b) let us try to see what its social function
has (or might) become.
(a) There is reason to believe that natural selection has won our minds
because it has been the only (thereby being representable as the only
possible) theory of organic evolution. I here simply note that the concept
of evolution in general (including cosmic, organic and cultural
evolutions) has itself captured the imagination of our society in this
century for various reasons, among which has been a struggle to get free
of religious bonds standing in the way of various projects. In this light,
we need to see that Darwinism is only one theory of evolution, of which
there might be others (this realization is itself liberating). True, there
is not at present any competing, equally well-developed, theory of organic
evolution (which is partly due to the competitive operations of
selectionists believing the validity of their theory). The question of why
natural selection has grown so formidably in adherents despite having had
few practical implications is referable back to (1), (2) and (3) above.
So, it can be seen that, until very recently,
natural selection has had a largely ideological role, as supplying a
conceptual mechanism for what we can view as Modernism's origination myth
-- evolution (I use "myth" in its ethnographic sense here, as a believed
story of why we are here, how we got here, and what we are doing here). It
has not yet succeeded in colonizing evolution theories in all fields -- it
still is not prominent in cosmic evolution, for example. In part this is
because some so-called theories of evolution (so-called "general
theories") are in reality theories of development. Natural selection has,
however, broken into studies of ontogeny (organismic development), even as
many students of phylogeny (organic evolution) questioned its usefulness
there.
(b) Recently there has been a championing of natural selection as a
medical principle, thereby gaining for it a more pragmatic importance in
order to better justify monies spent studying it. The major insight here
is that microorganisms (and some insect pests as well) can mutate and
evolve incredibly rapidly -- especially when challenged with antibiotics
(or pesticides), or, indeed, antibodies. The response to these challenges
can be understood easily using a selection model. This realization has led
to altered uses of these agents, and so the selection model has had
practical results. (I do not here include the relation of the selection
concept to breeding programs on domesticated organisms. These were under
way, and mostly completed, long before natural selection was thought of,
and, indeed, the idea was originally only a metaphor for them -- Nature
doing the selecting instead of people. So the influence was the other way
around here.) Various trends in biotechnology are
based in genetics, and, since genetics has become central to modern
neoDarwinian theory, this seems to confer upon this theory some panache by
association. However, most of what transpires in biotechnology could go on
without any theory of evolution at all. Genetics validated the Darwinian
theory (by supplying material causes for inheritance), not the other way
around. We can do genetic manipulations without considering natural
selection, or even evolution, at all. But, of course, the neoDarwinian
theory fits snugly into our current rage for genetics in biology.
In the realm of computing we have various programs
that instantiate the theory of natural selection (e.g., genetic
algorithms), or something like it. Certainly here the theory came first,
and it has been influential in, say, robotics. Even in this area, however,
much of its seeming influence may really have come from behaviorism,
another mechanistic theory which formally has the same structure as
selection theory -- selection by consequences -- as pointed out by B. F.
Skinner. I think it fair to conclude that natural
selection's social role is still primarily to supply an ideological
mechanism for a favored myth.
(5) its privileging the centrality of competition.
In an increasingly overcrowded world, it happens that more people are
coming to believe in the evolution of organisms, including people, by way
of natural selection -- which works fundamentally on the principle of
competition between types. You and I as individuals cannot compete in this
game, but, as tokens of various types (blue eyes / brown eyes; dark skin /
light skin -- each of us is a nexus of many genetically coded types) our
reproductive success contributes to the competition for representation of
these types in the population (and of the genes governing them in the gene
pool). It is curious that there is an obvious correlation between holding
liberal political views and believing in evolution by natural selection --
seemingly a flat contradiction! This probably ought to be the most
troubling aspect of selection theory for liberals. Darwinian models have
supplied motivation for social Darwinists of one kind or another ever
since World War I, ranging from the German High Command at the turn of the
century to some contemporary sociobiologists. We might note here that many
sociobiologists hold that competition between populations (e.g., among
humans, warfare) is a reasonable way to sublimate competition between
types in a population (see discussion of interspecific competition in the
last paragraph of (6), below). Irons' review of R.D. Alexander's book The
Biology of Moral Systems concludes that the fact that it presents such an
unpleasant perspective doesn't make it wrong. The answer to this view is
to bring up the social construction of knowledge, where we see that what
is desired can be constructed as true. Sober and Wilson's recent book,
Unto Others, devoted to tracing the evolution of altruism, is nevertheless
based on competition, as any Darwinian text must be.
(If one wishes to catch the moral and philosophical
flavor of Darwinian implications, the Alexander book cited above, and
Monod's Chance and Necessity are central readings.)
It has often been suggested that such social Darwinian applications are
"misuses" of the theory. Well, I think that a theory that has so strong a
propensity for this kind of (mis)use could properly be held to be suspect
when its adherents are growing apace along with the world population. Or,
more innocently, we might ask in just what way a theory that privileges
competition as the source of everything is ideologically appropriate to an
increasingly overcrowded world. Perhaps it is!
(6) Moving now into consideration of details of the formal
properties of the idea of natural selection, we can start very broadly
by noting that it is basically a theory of, as Einstein might have
remarked, higgledy-piggledy. That is, it is a theory of constraints on
randomness -- or, indeed a theory of accidental changes.
Randomness is deeply fundamental to the theory in
the sense that its major purpose was to find a model of evolution that did
not involve any force giving it direction. This relates directly to its
ideological challenge to religious views on the origin of humans. (It is
amusing -- and perhaps important -- to note that one cannot distinguish
between a random event and an arbitrary one! The former is just a default
reading of the latter, which would be a creative act.)
The randomness in neoDarwinism has been read into
the mutation process, which seems eminently plausible given the DNA model
of genes -- and this continues to be appropriate even after it had been
shown that some combinations of bases are less stable than others. After
all, almost any material system will have structural biases, and the
effects of contingency just work around these, delivering various random
distributions like the lognormal, the negative binomial, and so on, in
different cases. Actually, these numerous
distributions bring up a subsidiary point about use of the term "random".
Random distributions are knowable by way of the various statistical
moments, like the mean, shown by ensembles and populations. External
forces might be thought to be able to influence these in subtle ways (as,
if they were of large scale with respect to organisms), and so we see that
randomness is not really the best way refer to what the Darwinians need
here. Lewontin has suggested that they use capriciousness instead. Each
and every change must be capricious, reflecting pure contingency. This
means also that choice is being made here between two major
interpretations of randomness -- as being a result of ignorance on the
part of the observer, or as reflecting a basic indeterminacy in a system.
The choice must go to the latter. Otherwise, again, some external force,
unknown to us, might be influencing relevant statistical moments.
Stated exactly (Mary Williams), the Darwinian
randomness of mutations means random with respect to the needs of the
organisms experiencing them. So, not only is there to be no external force
influencing evolution, organisms themselves cannot be allowed to be agents
in their own evolution either. This puts away most Lamarckian models, in
which organismic agency is the main point. And it allows the theory to be,
as it is, mechanistic. So, mutation is held to be
random. Randomness functions elsewhere in models of organic evolution,
most notably in speciation. The most widely supported model of speciation
is the allopatric model of Ernst Mayr. In this model selection need not
have any role at all. All that is needed is for populations to become
isolated from each other so that gene flow is interrupted for significant
periods of time, and then the genomes will diverge randomly by way of
mutation until the point where, if the populations were to become
contiguous (sympatric) again, they could no longer interbreed
successfully. (The process of becoming isolated is also taken to be random
with respect to any agency of, or within, the populations -- as, e.g., by
way of continental drift.) Selection could speed up the process of
divergence, and it might also work to reinforce it upon renewed sympatry,
but it is logically not a necessary part of the model. Sympatric
speciation models, on the other hand, all require natural selection, but
no one suggests that they would be responsible for other than a small
number of speciations that posed problems for the allopatric model. And in
these cases, as in all, mutations would still be random.
Further applications of randomness to the Synthetic
Theory of evolution (neoDarwinism extending its conceptual reach into
morphology, ontogeny, paleontology and ecology) include genetic drift,
preadaptation (prospective adaptation), and environmental change itself.
Genetic drift is interesting because it shows well
how Darwinism is at base a theory of hazard. As populations become
smaller, sampling errors conspire to drive their gene pools apart
statistically because deterministic forces (as selection is often imagined
to be -- but see below) cannot function effectively in small populations.
In these models we clearly see that selection is just a bias on
randomness, and its effects weaken as the effectiveness of statistical
predictive techniques weaken as a population declines. Furthermore,
although usually described as a force that can oppose selection in small
populations, in populations of modest size (as in most animals and plants)
one of the major roles of drift is to give the coup de grace to any genes
that have become reduced in frequency (as by selection) below a certain
level. Only this force -- the chance deaths of the few remaining survivors
-- is capable of totally eliminating an allele from a gene pool.
Preadaptation is the situation where, by chance,
some characteristic(s) of a kind of organism would allow it to explore,
even if not very effectively at first, some new way of life. Such
unexpected potential utilities would be an unavoidable property of any
complex system. Providing that environmental changes make such a new way
of life possible, and providing that no other populations are working some
similar way of life in the same region, then a population might shift into
a new niche, with time for selection to improve its ability to live this
way without competition from other populations. The shift is often seen as
being carried by behavioral exploration, which, however, might be
problematic for Darwinians in that, unless we can take organisms to be
machines, this could open up possibilities for their agentive action in
their own evolution (as in the niche construction heresy). As I will show,
organisms are taken to be mechanistic by Darwinians, and so exploratory
behavior can be viewed as just the occasional, and not necessary,
realization of accidental propensities via fluctuations and excursions.
Since there is in Darwinism no theory of the
environment, environmental change is always viewed as formally accidental
(in models it is just an arbitrary declaration), and it often occurs in
any case at a scale that is beyond any effects a population might have on
its environment. Even if some larger force were directing such changes,
they could not have any relation to the needs of populations of organisms.
Insofar as the environment of a population is
composed of populations of other species, there is a kind of theory of the
environment in Darwinism in what Darwinians have called "community
ecology". We can begin with Gause's competitive exclusion principle, which
states that not more than a single population can occupy a given
(Hutchinsonian) ecological niche. If it should happen that there comes to
be niche overlap between sympatric populations, the process of character
displacement (Brown and E.O. Wilson), (by way of which phenotypes in a
population that exploit resources most different from those exploited by
other contiguous populations will tend to succeed better than others) will
drive all the populations in a region apart ecologically. This will
deliver a niche plenitude such that all available energy gradients in a
region will tend to get exploited. Van Valen has postulated that this
situation will deliver a "continuous deterioration of the environment",
since any population that does better for a few generations, expanding its
hegemony, will create energy shortages for some other populations, and
that this will spread in a region, resulting in a continual jostling for
resources among contiguous populations that can never settle down because,
even just by way of fluctuations, some population will eventually come to
do better than it has done. (The implication here is that each population
has maximized its energy throughflow, and that energy is fungible from
niche to niche, delivering an energetic zero-sum game.)
Summing up, we can see that the import of the
Darwinian theory of evolution is just unexplainable caprice from top to
bottom. What evolves is just what happened to happen. For Darwinians,
organic evolution is, precisely, pointless.
(7) It incorporates no theory of origins.
Despite the title of Darwin's book, he disavowed any application of his
selection idea to origins. For him in his book, the origin of species was
just the gradual transformation of organisms in a given population as a
result of selection over a long period of time, so that, if a naturalist
were to examine specimens from the original population and some from the
latest, he would be inclined to declare them to be from different species.
Simpson called this phyletic evolution, as opposed to lineage splitting
(Rensch's cladogenesis). (Darwin even rejected the idea of an allopatric
model of cladogenesis when it was put to him by Moritz Wagner, probably
because, as mentioned above, that model does not require selection). A few
workers have been trying to incorporate variation generation into the idea
of natural selection, but without eliciting any general interest, or
having much success. Selection, formally, is just culling (see below).
It is perhaps worth mentioning that the core of
neoDarwinism, population genetics theory, is fundamentally mathematical.
In mathematics, crisp as that (which has been used) is, nothing new can be
generated -- except by way of error. (If the theory were to be translated
into fuzzy set theory, or, even better, recast in some kind of logic of
vagueness, the possibility might arise of having a mathematics that could
generate new categories.) After variants are
generated at random with respect to needs, the selection regime itself is
just a negative, mechanical, process of culling. In the resulting
mythology we are, as George Wald quipped, the products of editing, not of
writing. To make this more clear, consider monkeys at keyboards. If they
type lines of letters, these could be made, by deleting and joining
adjacent letters, into a series of words, which, with further editing and
leaving spaces, could be joined up into simple texts. This would be
analogous to adaptation (here, the generation of meaning) within some
environment (in this case, a language and its traditions) based on a
random generation of units. (It may be objected that the deletion and
joining done here actually reflects intentional activity, and so this
would be a model of artificial selection rather than of natural selection.
Well, intentionality of some sort is a necessary part of the system when
using a linguistic model. In that framework I would model artificial
selection as above, but with there being a given text in mind when the
cutting and joining is done.) The negativity of the
action of selection is clearly reflected in the equations of population
genetics, where, in the Fisher version, the fitness of given types, m, =
births minus deaths (and failures to reproduce). In the Wright-Dobzhansky
version, fitness, W, = 1 minus the selection coefficient. That is,
selection is represented as a deficit from maximum performance. The action
that is modeled in population genetics is not variability generation, but
its culling (see discussion of the Wright-Dobzhansky model in the next
section for a small qualification). A related point
arises with frequent use of the phrase "selection for something". This is
just an oxymoron of loose usage, as I will explain further in (9), below.
(8) its failure to explain, as Darwin hoped it would, evolutionary
improvement of phenotypic characters and behaviors.
It has been noted that much of the history of Darwinism in the
Twentieth Century involves a gradual divestment of all notions of
progressive evolution. Another way of putting this would be that the
theory has been purified of all developmental aspects. This has also moved
the theory away from theories of general evolution. Unwittingly (one would
suppose) this has undermined the possibility for Darwin's improvement as
well. In mid century, improvement was discussed
under the heading of evolutionary trends. These were later deconstructed
by noting that they were actually constructed from contemporary (target)
morphological forms of special interest, working backward through the
fossil record so as to reconstruct intelligible stories when read forward.
When examined more closely, most of these stories fell apart, or, at
least, became much more complicated and ambiguous. Coupling this with the
actual form of Darwinian theory (see below for more details) showed that
it gave no support for evolutionary trends except as accidental
by-products of the survival of populations from one generation to the
next. The phrase "the evolution of this or that", so common in museum
displays, became oxymoronic. For example, the putative selection processes
that left certain dinosaurs with feathers could not be assimilated to a
story of the evolution of flight, or of the evolution of wings, except as
a post hoc view from the present. There would have been, in a Darwinian
interpretation, no processes that actually operated as the "evolution of"
anything, just a haphazard survival of concatenations of populations
adapting in the short term to local conditions. Darwinians do acknowledge
that there might be biases in the directions evolution might take in given
lineages, but these are viewed as having been built into the system as
results of historical accident, preserved by a kind of developmental
inertia (the system has a memory, and does not go back to square one with
the development of every new organism). Natural
selection can be directly demonstrated in laboratory and field
experiments, and has many times been shown indirectly to (most likely)
have been occurring in nature, but its connection to long term evolution
is an inference only -- especially since the theory shows no detailed
structure that would allow such a connection (see below). Observations of
the effects of selection in natural populations support the idea that
selection plays a negative role in preserving well-adapted types.
Experiments on microorganisms have shown that some trait, originally
poorly represented in a population can come to predominate after the
environment was altered. The idea that traits can be improved by selection
has its empirical support from just these two lines of evidence.
There are two major theoretical prongs in
neoDarwinism: the Fisherian dynamical approach and the Wright-Dobzhansky
kinetic approach. Neither delivers real long term evolution. In Fisher's
version, which does track over many generations, we begin with a
population having a degree of variability in characters that could link to
fitness. The environment changes, and, as a result of differential
reproduction, some variants are discarded from the population while a few
increase in frequency of representation. This process, generation after
generation, results in a net decrease in population variability in fitness
as population fitness with respect to the altered environment improves
(Fisher's fundamental theorem of natural selection). This genic
improvement could reasonably be linked to some phenotypic evolutionary
trend. By the time the population has achieved an adaptive gene pool
configuration (if it hasn't gone extinct for lack of appropriate
variability), it has lost variability to the extent that, if the
environment should change again, extinction would be a likely result. The
population has become overspecialized. In this model, evolution leads to
the brink of extinction. Of course, one would posit the introduction of
new variability by way of mutations to replace what was lost, but that is
not represented in the theory, only stuck on for verisimilitude in the
minds of biologists. We might note that there are examples of ecologically
seemingly overspecialized organisms (using only a single food supply, for
example), and these tend to be statistically quite rare, often with small
populations in inaccessible environments, suggesting that slight
environmental changes would lead to their extinction. Fisher's model
perhaps works well enough to explain these. Turning
to the Wright-Dobzhansky model, this is concerned with preserving
variability from one generation to the next, and does not track evolution
over the generations as does the Fisher model. The purpose of this version
is not to show evolution, but to model how populations contrive to survive
from one generation to the next. Crucially, the environment deteriorates
each generation, and the game is to try to get, or preserve, as much
variability as possible, so as to be ready to survive the next
generation's unpredictable environment. Gene frequencies shift back and
forth from one generation to the next, getting nowhere in particular.
Observations on natural populations of Darwin's finches in the Galapagos
Islands reflect this pattern. One might have the bright idea to combine
Fisher with Wright-Dobzhansky (and many evolutionists do so implicitly),
but that is not really possible technically because m is a dynamical,
continuous variable, while W is a discrete variable. The purposes and
techniques of the two models are different. One might loosely combine the
two into a general philosophical viewpoint, and what one comes up with
then is: evolve at your risk; just try to stay in the game as long as
possible! This reminds one of the Brooks-McLennan
view that the major role of natural selection is just to preserve existing
adapted phenotypes by weeding out abnormalities -- that is, to maintain
adaptedness. It should be mentioned in this connection that many of the
indirect demonstrations of selection in nature evidently refer to a
process of this kind. They show (a) that individuals that tend to get
eliminated by drastic environmental deteriorations (winter storms, etc.)
are those with measurements at or beyond a standard deviation from the
mean for the population, or (b) that traits demonstrated (or more likely)
to be more crucial to survival tend to be less variable than traits that
seem less important (as if the former have been subjected to greater
selection pressures). There has been no demonstration in nature of long
term evolution of a new adaptive configuration following an environmental
deterioration. Some putative examples, like industrial melanism in moths,
turned out to be much more ambiguous than at first thought. Others (as in
studies of Darwin's finches) show selection in different directions
resulting from repeated experiences of the same environmental problem
(drought), rather than the reinforcement of the direction of selection
from one episode to the next that would be required for directional
evolution to deliver improvement. Selection
experiments with microorganisms running over many of their generations do
show improved adaptation of a trait (usually resistance to some toxic
substance) in a given direction. Beyond noting that this kind of
experiment, considering the high intensity of the selection pressure
constructed on a single trait, is very like artificial selection
experiments, I will point out below that population genetic theory can
indeed support directional evolution of single traits. It just has not
been demonstrated in nature. Here we should note
two large reviews of many studies of natural selection in natural
populations (Endler, Kingsolver et al.). They both found evidence for the
balancing selection just mentioned above, which merely maintains the
adaptedness of populations. The more recent study claims that there is as
much evidence for "disruptive selection" in the data. The implication
within this study is that this disruptive selection (the variability of
the trait is greater after selection) is actually directional selection,
which I am throwing into doubt here. But there are other kinds of
selection that could be responsible for increasing the variability of a
population, which have been argued by some to be very important in nature
-- forms of balancing selection like density and frequency dependent
selection. And directional selection should have this effect only early in
its progress, thereby providing evidence only for the beginnings of
improvement here. In passing I should mention that the more recent study
noted that for the most part selection is a very weak force in nature. Is
this held against the study? Not at all! It is what would be expected
within the general Darwinian view that evolution by selection is a very
slow, long drawn-out process. We should note again
here (see 1, above) that the values that emerge implicitly from thinking
about our own evolution in these ways are: short term gain, expedience and
opportunism. Natural selection, being a mechanistic process, cannot
foresee the future. It works ("tinkers", as Jacob said) with whatever raw
material is at hand to produce (population and genotype) survival now.
Herbert Simon achieved a Nobel Prize by applying this principle to
economics, with his idea of "satisficing". He showed that, over the long
haul, global planning for the future does no better in cost / benefit
analysis than the local strategy of reacting, and fixing things serially,
as problems emerge. But this was just a reading back into economics of a
principle that, in light of Darwin's being influenced by classical
capitalist economic theory, came from there originally (Nietzsche thought
Darwin thought like an English shopkeeper!). Of course, Simon's
achievement was a mathematical one, and, once again, I would point out
that explicit mathematics is a mechanistic system, and so we do not really
know to what degree satisficing would be the best strategy in the natural
world which, although it appears to have some properties that may be
approximately modeled as mechanisms, is certainly not a machine.
So, with current neoDarwinian theory, we can claim
that it does not model evolution, only short term survival from one
generation to the next.
(9) its failure to model generally the evolution of more than a
single phenotypic trait during a given period (I would suppose that
there might be multigene models for special ideal conditions, like
haploidy, no population structure, non-overlapping generations, very large
populations, etc.). This came to light when J.B.S.
Haldane noted that the fitnesses of independent traits would have to be
combined multiplicatively, and that this would so rapidly increase the
cost of natural selection (in the deaths / failures required for favorable
alleles to replace others) as more traits are considered, that one could
not imagine the simultaneous evolution of more than one or two phenotypic
traits in populations of moderate sizes (as in most animals and plants).
Are phenotypic traits actually selected
independently? Of course, more than a single unfavorable character state
could occur, and be eliminated simultaneously, in the same individual, but
Haldane considered this in his calculations. One might note that traits
would really function independently only in machines. But it is clear that
organisms are considered to be mechanistic in the calculations used in
science, and also in Darwinian theory. Crisp, explicit mathematics
requires this drastic approximation. Read any description of organismic
adaptation and you will find that traits are described separately (for
whatever reason) as if they were tools used by organisms for adaptation.
The measurement of bird beaks is a commonly cited example. Length, width
and height are each considered separately. Even if multivariate statistics
finds a way to combine such measurements, the beak would still be
considered separately from, say, the legs. Several
workers came up with essentially the same general solution to "Haldane's
dilemma", but it comes at the price of not being able to consider
individual phenotypic traits as subjects of evolution at all. Bruce
Wallace's "soft selection" is a well-known, representative technique.
Beginning with the key Darwinian fact that organisms produce offspring way
in excess over what can be supported by their environments, Wallace
postulated that individual survival and reproductive success would be
keyed to the number of favorable character states individuals had. Those
with serious developmental or physiological problems would be eliminated
first, those not quite as badly off next, and so on down to reproductive
competition between sound individuals. Organisms are being compared, not
on the basis of this or that trait, but on global fitness. While only
fitness is maximized, individual trait measurements would be jointly
optimized. But no individual traits are represented in this theory, and so
it is useless to those who, like evolutionary morphologists, consider the
evolution of such traits. They would still be left with Haldane's dilemma,
and so would be the layperson interested in the evolution of, say, eyes or
brains (or, indeed, of humans), which have numerous traits influenced by
numerous genes. I should mention the remarkable
feats being reported concerning the use of selection in computation to
design shapes, robots and products using the likes of 'genetic
algorithms'. The claim here is that, given a complex shape coded for by
several to many "genes", a selection process can be instituted to improve
any function imposed upon that shape. The resulting shape changes are not
predictable (not built into the program to begin with), nor is the
trajectory taken during the improvement. In other words, this models a
multigene selection process. However, it does not escape Haldane's
dilemma, because there is only one function being selected at a time --
one selection pressure. Perhaps two functions could be optimized
simultaneously, given a large enough population of robots. This is not
like selection among organisms, where only fitness is maximized, not any
particular function. Another disanalogy can be seen when we note that
much, if not most, genetic information in organisms is pleiotropic. This
means that not just any old change that will improve some function can be
selected in organisms without consequence for other functions. The
selection model seems to work better in genetic algorithms than it could
in organisms! Reference to the opportunism of
adaptation could be brought up here again. Given the complexity of the
phenotype, no particular solution to an environmental challenge could be
privileged. If we have a population of mammals in a region which is
getting colder, they could respond by (a) getting larger, (b) getting
smaller and going fossorial, (c) growing thicker fur, (d) going dormant
for the coldest season, (e) migrating seasonally, and so on. One could not
really even define the environmental problem coming out of, say, a colder
environment, without considering in detail the form and lives of a
particular population. We can here consider an
oxymoron commonly used by evolutionists -- "selection for this or that
trait". Aside from the fact that selection pressure is modeled negatively
in mathematical models (see (7), above), we can now see, in this quite
reasonable soft selection model, that no phenotypic trait could be
isolated as showing a character state that is favored by natural selection
(any more than any other one evolving simultaneously). Selection for
something can only be modeled in cases like artificial selection, where
human agency repeatedly applies truncation selection on a given trait.
Using the monkey at keyboards analogy again (see (7), above), we could
model selection for something by having the inspection of the random
letters be informed by a pregiven text. There is one other possibility
where selection for could be used, but neoDarwinians are not likely to
embrace it. It would be possible to have a
single-trait Darwinism in which traits are viewed as evolving one at a
time, sequentially, with the information from each new allele being
assimilated into a developmental system which oversees the construction of
the phenotype. The problem with this for Darwinians is that this
privileges the ontogenetic system as the site of all the action, with
selection just providing tokens or memory bench marks cuing that system
into modulating some developmental processes. This view would also go
against the current enthusiasm for genetic reductionism shown in phrases
like "this trait is coded for by by gene X", and would make nonsense of
the popular Dawkins / Dennett genic reductionism.
(10) The internal contradiction in its major theoretical cornerstone
-- Fisher's fundamental theorem As mentioned above, Fisher's
theorem has it that population variance in fitness is exchanged over the
generations for population fitness increase. A corollary would be that
traits having been subjected to heavy selection pressures, because of
their importance in the lives of the organisms, should be less variable
than less important traits. This has been found in traits judged to be of
importance for jumping in frogs (Salthe and Crump, 1977), and also these
traits were not found to be significantly less variable than others in
populations of frogs that walk but do not jump. Now, at the same time,
note that when asked which traits are most likely to be able to evolve,
evolutionary biologists, again citing Fisher's theorem, will reply, "those
that have more variability in fitness". That is to say, traits that have
been most important in the lives of organisms up to this moment will be
least likely to be able to evolve further!
(11) its ability to explain only differences between characteristics
of different, genealogically related, types.
This follows from the fact that genetic configuration, rather than
material processes, are considered to be the locus of inheritable
information. Genetic information allows the developing system to place
constraints on material processes, modulating them, slowing some down
while speeding others up. Form itself, or behavior, as such, cannot be
attributed to genes, because these phenomena are the products of physical
activity. The cell uses DNA information to inform its (formally
preexisting) activities. You can inherit a different style or rate of
construction, while you are a material locus of processes of construction.
The material differences between a wolf and a deer are slight; their
genetic information differentiates them functionally -- semiotically.
These facts are reflected in the techniques of
genetics, where, if there is no phenotypic difference between two types,
no gene will imputed to exist. The operational definition of a gene is a
difference in DNA that makes a difference to metabolic activities and
their resultant forms. Many examples of DNA differences unconnected to
phenotypic signs are known. It is sometimes claimed that once the
DNA-protein system was understood, the gene had become materialized, and
so no longer needed to be tied to its operational definition as a
difference. Yet, no gene is discovered without there first being an
associated phenotypic difference. Especially now that we know that genetic
information for given properties is scattered around in the genome, rather
than being localized according to traits, to speak of genes for this or
that trait is a mere reification. Genes have now become constructed as
differences in patterns of activity. Given these
views, we can see that only differences between types require genetic
information in order to be explained. Indeed, some differences may not be
genetic either, but I think it fair enough for biologists to presume
genetic differences where phenotypic ones are found -- when comparing
closely related forms. Differences between such distantly related forms as
snails and wolves need not reflect differences in particular genes. And
similarities, even between closely related forms, require no genetic
information to explain. From the point of view of genetics, similarities
are taken to be just the absence of differences. They are non-phenomena.
We may indeed find similar genetic forms among very distantly related
organisms, as in the HOX genes, yet not infrequently these similar genes
perform different functions (albeit in the same general system) in these
different forms. So, genetic information is needed
currently to explain niche differentiation among recently diverged
organisms. In fact, that is what natural selection can be used, with the
above reservations [especially in (9)], to explain.
(12) its inability to explain similarities between organisms and
ecological systems that are not related by descent.
Parallel evolution, convergent evolution, and ecological vicariance
have no explanation using Darwinian models, which are based solely in
descent with modification, which, as just considered, can explain
differences, not similarities. Hence important cases like the similarities
in the eyes of cephalopods and vertebrates have no natural explanation
within Darwinism -- except, once more, the all pervasive chance. There
have been some preliminary attempts to locate such similarities as results
of a wholesale transference of genes, by way of viral infection, from one
kind of organism to another. This would fit with Darwinian views, and we
can expect this idea to be exploited for whatever it may be worth. In the
meantime, convergent evolution tends not to get mentioned at all in
important texts.
Conclusion:
Finally, then, it is my conclusion that the Darwinian (Synthetic)
theory of organic evolution, insofar as it is crucially driven by the
concept of natural selection, is not suitable to be a part of Modernism's
creation myth. At a time when the world is becoming crowded, it seems
little conducive to peace to believe that competition, which is the basis
of natural selection, is the source of all good (including ourselves),
however well such a belief might fit with our current economic system.
As to its ability to explain the evolution of
organisms (as opposed to the evolution of gene systems), it has not, after
some 60 years of development, delivered a very convincing mechanism. It
cannot explain origins, or the actual presence of forms and behaviors. It
can generally explain only the evolution of adaptive differences as
results of historical contingency, for only one or two traits at a time.
It is limited to historical explanations, as it acknowledges no
evolutionary tendencies that are not the result of accident preserved in
genetic information. History is the source of everything in this theory,
and that is just too simplistic to be plausible in a complex material
world. I think it could be said that, were there another theory of organic
evolution, the neoDarwinian one, fraught with problems as it is, would
have more trouble surviving. As it is, it is the "only game in town",
largely because of the competitive activities of the neoDarwinians
themselves.
Postscript [of February 2003]:
As added support for the viewpoint projected herein, I cite two of
Richard Lewontin's works. First, his The Genetic Basis of Evolutionary
Change, (1974, Columbia University Press) has a discussion of the
effects of linkage disequilibrium among genetic loci on the process of
selection that makes it seem highly unlikely that selection could be very
effective in improving a trait using a more realistic model of the genome
than is usually used. Recently he has produced a
paper for the Santa Fe Bulletin [Volume 18 (1), Winter, 2003] which
raises four "complications" to the theory of natural selection that seem
to me to cripple it altogether.
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