TABLE OF CONTENTS Page
INTRODUCTION ……………………………………….. 2
DARWINIAN THEORY OF EVOLUTION ………………………… 4
THE THEORY OF BIOLOGICAL EVOLUTION:
CONTRIBUTING ELEMENTS ………………….. 7
WALLACE’S CONTRIBUTIONS …………………………….. 13
HARDY-WEINBERG PRINCIPLE ……………………………. 15
COMPARISON: LAMARCK vs. DARWIN ……………………… 16
DARWIN’S INFLUENCES ………………………………… 20
METHODS OF SCIENTIFIC DEDUCTION ……………………… 23
LIMITS TO DARWIN’S THEORY …………………………… 25
MORPHOLOGICAL ; BIOLOGICAL CONCEPTS ………………….. 27
BIO-EVOLUTION: POPULATION vs. INDIVIDUALS ……………. 29
MECHANISMS FOR GENETIC VARIATION …………………….. 31
GENETIC VARIATION AND SPECIATION …………………….. 35
DARWIN’S FINCHES …………………………………… 37
SPECIATION vs. CONVERGENT EVOLUTION ………………….. 39
CONCEPT OF ADAPTATION ………………………………. 41
PUNCTUATED EQUILIBRIUM ……………………………… 43
VALUE/LIMITATIONS: THE THEORY OF BIOLOGICAL EVOLUTION …. 45
ALTERNATE EXPLANATIONS OF BEING ……………………… 47
CONCLUSIONS ……………………………………….. 48
INTRODUCTION
Theories explaining biological evolution have been bandied
about since the ancient Greeks, but it was not until the
Enlightment of the 18th century that widespread acceptance and
development of this theory emerged. In the mid 19th century
english naturalist Charles Darwin – who has been called the
“father of evolution” – conceived of the most comprehensive
findings about organic evolution ever1. Today many of his
principles still entail modern interpretation of evolution.
I’ve assessed and interpreted the basis of Darwin’s theories
on evolution, incorporating a number of other factors concerning
evolutionary theory in the process. Criticism of Darwin’s
conclusions abounds somewhat more than has been paid tribute to,
however Darwin’s findings marked a revolution of thought and
social upheaval unprecedented in Western consciousness
challenging not only the scientific community, but the prominent
religious institution as well. Another revolution in science of
a lesser nature was also spawned by Darwin, namely the remarkable
simplicity with which his major work The Origin of the Species
was written – straightforward English, anyone capable of a
logical argument could follow it – also unprecedented in the
scientific community (compare this to Isaac Newton’s horribly
complex work taking the scientific community years to
interpret2).
Evolutionary and revolutionary in more than one sense of
each word. Every theory mentioned in the following reading, in
fact falls back to Darwinism.
DARWINIAN THEORY OF BIOLOGICAL EVOLUTION
Modern conception of species and the idea of organic
evolution had been part of Western consciousness since the mid-
17th century (a la John Ray)3, but wide-range acceptance of this
idea, beyond the bounds of the scientific community, did not
arise until Darwin published his findings in 19584. Darwin first
developed his theory of biological evolution in 1938, following
his five-year circumglobal voyage in the southern tropics (as a
naturalist) on the H.M.S. Beagle, and perusal of one Thomas
Malthus’ An Essay on the Principle of Population which proposed
that environmental factors, such as famine and disease limited
human population growth5. This had direct bearing on Darwin’s
theory of natural selection, furnishing him with an enhanced
conceptualization of the “survival of the fittest” – the
competition among individuals of the same species for limited
resources – the “missing piece” to his puzzle6. For fear of
contradicting his father’s beliefs, Darwin did not publish his
findings until he was virtually forced after Alfred Wallace sent
him a short paper almost identical to his own extensive works on
the theory of evolution. The two men presented a joint paper to
the Linnaean Society in 1958 – Darwin published a much larger
work (“a mere abstract of my material”) Origin of the Species a
year later, a source of undue controversy and opposition (from
pious Christians)7, but remarkable development for evolutionary
theory.
Their findings basically stated that populations of
organisms and individuals of a species were varied: some
individuals were more capable of obtaining mates, food and other
means of sustenance, consequently producing more offspring than
less capable individuals. Their offspring would retain some of
these characteristics, hence a disproportionate representation of
successive individuals in future generations. Therefore future
generations would tend have those characteristics of more
accommodating individuals8. This is the basis of Darwin’s theory
of natural selection: those individuals incapable of adapting to
change are eliminated in future generations, “selected against”.
Darwin observed that animals tended to produce more offspring
than were necessary to replace themselves, leading to the logical
conclusion that eventually the earth would no longer be able to
support an expanding population. As a result of increasing
population however, war, famine and pestilence also increase
proportionately, generally maintaining comparatively stable
population9.
Twelve years later, Darwin published a two-volume work
entitled The Descent of Man, applying his basic theory to like
comparison between the evolutionary nature of man and animals and
how this related to socio-political development man and his
perception of life. “It is through the blind and aimless
progress of natural selection that man has advance to his present
level in love, memory, attention, curiosity, imitation, reason,
etc. as well as progress in “knowledge morals and religion”10.
Here is where originated the classic idea of the evolution of man
from ape, specifically where he contended that Africa was the
cradle of civilization. This work also met with opposition but
because of the impact of his “revolutionary” initial work this
opposition was comparatively muted11.
A summary of the critical issues of Darwin’s theory might be
abridged into six concise point as follows:
1Variation among individuals of a species does not indicate
deficient copies of an ideal prototype as suggested by the
platonic notion of Eidos. The reverse is true: variation
is integral to the evolutionary process.
2The fundamental struggle in nature occurs within single
species population to obtain food, interbreed, and resist
predation. The struggle between different species (ie. fox
vs. hare) is less consequential.
3The only variations pertinent to evolution are those which
are inherited.
4Evolution is an ongoing process which must span many moons
to become detectably apparent.
5Complexity of a species may not necessarily increase with
the evolutionary process – it may not change at all, even
decrease.
6Predator and prey have no underlying purpose for maintenance
of any type of balance – natural selection is opportunistic
and irregular12.
THE THEORY OF BIOLOGICAL EVOLUTION: CONTRIBUTING ELEMENTS
The scientific range of biological evolution is remarkably
vast and can be used to explain numerous observations within the
field of biology. Generally, observation of any physical,
behaviourial, or chemical change (adaptation) over time owing
directly to considerable diversity of organisms can be attributed
to biological evolution of species. It might also explain the
location (distribution) of species throughout the planet.
Naturalists can hypothesize that if organisms are evolving
through time, then current species will differ considerably from
their extinct ancestors. The theory of biological evolution
brought about the idea for a record of the progressive changes an
early, extinct species underwent. Through use of this fossil
record paleontologists are able to classify species according to
their similarity to ancestral predecessors, and thereby determine
which species might be related to one another. Determination of
the age of each fossil will concurrently indicate the rate of
evolution, as well as precisely which ancestors preceded one
another and consequently which characteristics are retained or
selected against. Generally this holds true: probable ancestors
do occur earlier in the fossil record, prokaryotes precede
eukaryotes in the fossil record. There are however, significant
“missing links” throughout the fossil record resulting from
species that were, perhaps, never fossilized – nevertheless it is
relatively compatible with the theory of evolution13.
It can be postulated that organisms evolving from the same
ancestor will tend to have similar structural characteristics.
New species will have modified versions of preexisting structures
as per their respective habitats (environmental situations).
Certainly these varying species will demonstrate clear
differentiation in important structural functions, however an
underlying similarity will be noted in all. In this case the
similarity is said to be homologous, that is, structure origin is
identical for all descended species, but very different in
appearance. This can be exemplified in the pectoral appendages
of terrestrial vertebrates: Initial impression would be that of
disparate structure, however in all such vertebrates four
distinct structural regions have been defined: the region
nearest the body (humerus connecting to the pectoral girdle, the
middle region (two bones, radius and ulna are present), a third
region – the “hand” – of several bones (carpal and metacarpal,
and region of digits or “fingers”. Current species might also
exhibit similar organ functions, but are not descended from the
same ancestor and therefore different in structure. Such
organisms are said to be analogous and can be exemplified in
tetrapods, many containing similar muscles but not necessarily
originating from the same ancestor. These two anatomical
likenesses cannot be explained without considerable understanding
of the theory of organic evolution14.
The embryology, or early development of species evolved from
the same ancestor would also be expected to be congruent.
Related species all share embryonic features. This has helped in
determining reasons why development takes place indirectly,
structures appearing in embryonic stage serve no purpose, and why
they are absent in adults. All vertebrates develop a notchord,
gill slits (greatly modified during the embryonic cycle) and a
tail during early embryology, subsequently passing through stages
in which they resemble larval amphioxus, then larval fishes.
The notchord will only be retained as discs, while only the ear
canal will remain of the gills in adults. Toothless Baleen
whales will temporarily develop teeth and hair during early
embryology leading to the conclusion that their ancestors had
these anatomical intricacies. A similar pattern, exists in
almost all animal organisms during the embryonic stage for
numerous formations of common organs including the lungs and
liver. Yet there is a virtually unlimited variation of
anatomical properties among adult organisms. This variation can
only be attributed to evolutionary theory15.
Biological evolution theory insists that in the case of a
common ancestor, all species should be similar on a molecular
level. Despite the tremendous diversity in structure, behaviour
and physiology of organisms, there is among them a considerable
amount of molecular consistency. Many statements have already
been made to ascertain this: All cells are comprised of the same
elemental organic compounds, namely proteins, lipid and
carbohydrates. All organic reactions involve the action of
enzymes. Proteins are synthesized in all cells from 20 known
amino acids. In all cells, carbohydrate molecules are
derivatives of six-carbon sugars (and their polymers).
Glycolysis is used by all cells to obtain energy through the
breakdown of compounds. Metabolism for all cells as well as
determination of definitude of proteins through intermediate
compounds is governed by DNA. The structure for all vital
lipids, proteins, some important co-enzymes and specialized
molecules such as DNA, RNA and ATP are common to all organisms.
All organisms are anatomically constructed through function of
the genetic code. All of these biochemical similarities can be
predicted by the theory of biological evolution but, of course
some molecular differentiation can occur. What might appear as
minor differentiation (perhaps the occurrence-frequency of a
single enzyme) might throw species into entirely different orders
of mammals (ie. cite the chimpanzee and horse, the
differentiation resulting from the presence of an extra 11
cytochrome c respiratory enzymes). Experts have therefore
theorized that all life evolve from a single organism, the
changes having occurred in each lineage, derived in concert from
a common ancestor16.
Breeders had long known the value of protective resemblance
long before Darwin or any other biological evolution theorists
made their mark. Nevertheless, evolutionary theory can predict
and explain the process by which offspring of two somewhat
different parents of the same species will inherit the traits of
both – or rather how to insure that the offspring retains the
beneficial traits by merging two of the same species with like
physical characteristics. It was the work of Mendel that
actually led to more educated explanations for the value in
protective resemblance17. The Hardy-Weinburg theory specifically,
employs Mendel’s theory to a degree to predict the frequency of
occurrence of dominantly or recessively expressing offspring.
Population genetics is almost sufficient in explaining the basis
for protective resemblance. Here biological evolutionary theory
might obtain its first application to genetic engineering18.
Finally, one could suggest that species residing in a
specific area might be placed into two ancestral groups: those
species with origins outside of the area and those species
evolving from ancestors already present in the area. Because the
evolutionary process is so slow, spanning over considerable
lengths of time, it can be predicted that similar species would
be found within comparatively short distances of each other, due
to the difficulty for most organisms to disperse across an ocean.
These patterns of dispersion are rather complex, but it is
generally maintained by biologists that closely related species
occur in the same indefinite region. Species may also be
isolated by geographic dispersion: they might colonize an
island, and over the course of time evolve differently from their
relatives on the mainland. Madagascar is one such example – in
fact approximately 90 percent of the birds living there are
endemic to that region. Thus as predicted, it follows that
speciation is concurrent with the theory of biological
evolution19.
WALLACE’S CONTRIBUTIONS
There is rarely a sentence written regarding Wallace that
does not contain some allusion to Darwin. Indeed, perhaps the
single most significant feat he preformed was to compel Darwin to
enter the public scene20. Wallace, another English naturalist had
done extensive work in South America and southeast Asia
(particularly the Amazon and the Malay Archipelago) and, like
Darwin, he had not conceived of the mechanism of evolution until
he read (recalled, actually) the work of Thomas Malthus – the
notion that “in every generation the inferior would be killed off
and the superior would remain – that is the fittest would
survive”. When the environment changed therefore, he determined
“that all the changes necessary for the adaptation of the species
… would be brought about; and as the great changes are always
slow there would be ample time for the change to be effected by
the survival of the best fitted in every generation”. He saw
that his theory supplanted the views of Lamarck and the Vistages
and annulled every important difficulty with these theories21.
Two days later he sent Darwin (leading naturalist of the
time) a four-thousand word outline of his ideas entitled “On the
Law Which has Regulated the Introduction”. This was more than
merely cause for Darwin’s distress, for his work was so similar
to Darwin’s own that in some cases it parallelled Darwin’s own
phrasing, drawing on many of the same examples Darwin hit upon.
Darwin was in despair over this, years of his own work seemed to
go down the tube – but he felt he must publish Wallace’s work.
Darwin was persuaded by friends to include extracts of his own
findings when he submitted Wallace’s work On the Law Which Has
Regulated the Introduction of New Species to the Linnaean Society
in 1858, feeling doubly horrible because he felt this would be
taking advantage of Wallace’s position. Wallace never once gave
the slightest impression of resentment or disagreement, even to
the point of publishing a work of his own entitled Darwinism.
This itself was his single greatest contribution to the field:
encouraging Darwin to publish his extensive research on the
issues they’d both developed22.
He later published Contributions to the Theory of Natural
Selection, comprising the fundamental explanation and
understanding of the theory of evolution through natural
selection. He also greatly developed the notion of natural
barriers which served as isolation mechanisms, keeping apart not
only species but also whole families of animals – he drew up a
line (“Wallace’s line”) where the fauna and flora of southeast
Asia were very distinct from those of Australasia23.
HARDY-WEINBERG PRINCIPLE
Prior to full recognition of Mendel’s work in the early
1900’s, development of quantitative models describing the changes
of gene frequencies in population were not realized. Following
this “rediscovery” of Mendel, four scientists independently,
almost simultaneously contrived the Hardy-Weinberg principal
(named after two of the four scientists) which initiated the
science of population genetics: exploration of the statistical
repercussions of the principle of inheritance as devised by
Mendel. Read concisely the Hardy-Weinberg principle might be
stated as follows:
Alternate paradigms of genes in ample populations will not be
modified proportionately as per successive generation, unless
stimulated by mutation, selection, emigration, or immigration of
individuals. The relative proportion of genotypes in the
population will also be maintained after one generation, should
these conditions be negated or mating is random24.
Through application of the Hardy-Weinberg principle the
precise conditions under which change does not occur in the
frequencies of alleles at a locus in a given population (group of
individuals able to interbreed and produce fertile offspring) can
be formulated: the alleles of a locus will be at equilibrium. A
species may occur in congruous correspondence with its population
counterpart, or may consist of several diverse populations,
physically isolated from one another25.
In accordance with Mendelian principle, given two
heterozygous alleles A and B, probability of the offspring
retaining prominent traits of either parent (AA or BB) is 25
percent, probability of retaining half the traits of each parent
(AB) is 50 percent. Thus allele frequencies in the offspring
parallel those of the parents. Likewise, given one parent AB and
another AA, allele frequencies would be 75 percent A and 25
percent B, while genotype frequencies would be 50 percent AA and
50 percent AB – the gametes generated by these offspring would
also maintain the same ratio their parents initiated (given, of
course a maximum of two alleles at each locus).
In true-to-life application however, where numerous alleles
may occur at any given locus numerous possible combinations of
gene frequencies are generated. Assuming a population of 100
individuals = 1, 30 at genotype AA, 70 at genotype BB. Applying
the proportionate theory, only 30% (0.30) of the gametes produced
will retain the A allele, while 70% (0.70) the B allele.
Assuming there is no preference for AA or BB individuals for
mates, the probability of the (30% of total population) AA males
mating with AA females is but 9% (0.3 x 0.3 = 0.09). Likewise
the probability of an BB to BB match is 49%, the remainder
between (30%) AA and (70%) BB individuals, totalling a 21%
frequency. Frequency of alleles in a population in are commonly
denoted p and q respectively, while the AB genotype is denoted
2pq. Using the relevant equation p + pq + q = 1, the same
proportions would be obtained. It can therefore be noted that
the frequencies of the alleles in the population are unchanged.
If one were to apply this equation to the next generation,
similarly the genotype frequencies will remain unchanged per each
successive generation. Generally speaking, the Hardy-Weinberg
principle will not favour one genotype over another producing
frequencies expected through application of this law.
The integral relevance for employment of the Hardy-Weinberg
principle is its illustration of expected frequencies where
populations are evolving. Deviation from these projected
frequencies indicates evolution of the species may be occurring.
Allele and genotype frequencies are typically modified per each
successive generation and never in ideal Hardy-Weinberg
equilibrium. These modifications may be the result of natural
selection, but (particularly among small populations) may simply
result from random circumstance. They might also arise form
immigration of individuals form other populations where gene
frequencies will be unique, or form individuals who do not
randomly choose mates from their wide-ranged species26.
COMPARISON: LAMARCK vs. DARWIN
Despite the lack of respect lamarckian theory was dealt at
the hands of the early evolution-revolutionaries, the enormous
influence it had on numerous scientists, including Lyell, Darwin
and the developers of the Hardy-Weinberg theory cannot be denied.
Jean Lamarck, a French biologist postulated the theory of an
inherent faculty of self-improvement by his teaching that new
organs arise form new needs, that they develop in proportion to
how often they are used and that these acquisitions are handed
down from one generation to the next (conversely disuse of
existing organs leads to their gradual disappearance). He also
suggested that non-living matter was spontaneously created into
the less complex organisms who would evolve over time into
organisms of greater and greater complexity. He published his
conclusions in 1802, then later (1909) released an expanded form
entitled Philosophie zoologique. The English public was first
exposed to his findings when Lyell popularized them with his
usual flair for writing, but because the influential Lyell also
openly criticized these findings they were never fully accepted27.
Darwin’s own theories were based on those of older
evolutionists and the principle of descent with modification,
the principle of direct or indirect action of the environment on
an individual organism, and a wavering belief in Lamarck’s
doctrine that new characteristics acquired by the individual
through use or disuse are transferred to its descendants. Darwin
basically built around this theory, adding that variation occurs
in the passage each progressive generation. Lamarck’s findings
could be summarized by stating that it is the surrounding
environment that has direct bearing on the evolution of species.
Darwin instead contested that it was inter-species strife “the
will to power” or the “survival of the fittest”28. Certainly
Lamarck was looking to the condition of the sexes: the
significantly evolved difference of musculature between male and
females can probably be more easily explained by Lamarckian
theory than Darwinian. There was actually quite a remarkable
similarity between the conclusions of Darwin’s grandfather,
Erasmus Darwin and Lamarck – Lamarck himself only mentioned
Erasmus in a footnote, and with virtual contempt. The fact is
neither Lamarck nor Darwin ever proposed a means by which species
traits were passed on, although Lamarck is usually recalled as
one of those hopelessly erroneous scientists of past it was
merely the basis for his conclusions that were hopelessly out of
depth – the conclusions were remarkably accurate29.
DARWIN’S INFLUENCES
In 1831 a young Charles Darwin received the scientific
opportunity of lifetime, when he was invited to take charge f the
natural history side of a five year voyage on the H.M.S. Beagle,
which was to sail around the world, particularly to survey the
coast of South America. Darwin’s reference material consisted of
works of Sir Charles Lyell, a British geologist (he developed a
concept termed uniformitarianism which suggested that geological
phenomena could be explained by prevailing observations of
natural processes operating over a great spans of time – he has
been accused synthesizing the works of others30) who was the
author of geologic texts that were required reading throughout
the 19th century including Principals of Geology, which along
with his own findings (observing the a large land shift resulting
from an earthquake), convinced him of geological
uniformitarianism, hypothesizing for example, that earthquakes
were responsible for the formation of mountains. Darwin
faithfully maintained this method of interpreting facts – by
seeking explanations of past events by observing occurrences in
present time – throughout his life31. The lucid writing style of
Lyell and straightforward conclusions influence all of his work.
When unearthing remains of extinct animals in Argentina he noted
that their remains more closely resembled those of contemporary
South American mammals than any other animals in the world. He
noted “that existing animals have a close relation in form with
extinct species”, and deduced that this would be expected “if the
contemporary species had evolved form South American ancestors”
not however, if thereexisted an ideal biota for each environment.
When he arrived on the Galapagos islands (islands having been
formed at about the same time and characteristically similar), he
was surprised to observe unique species to each respective
island, particularly tortoises which possessed sufficiently
differentiated shells to tell them apart. From these
observations he concluded that the tortoises could only have
evolved on the islands32.
Thomas Robert Malthus was an English economist and clergyman
whose work An Essay on the Principal of Population led Darwin to
a more complete understanding of density dependent factors and
the “struggle in nature”.Malthus noted that there was
potential for rapid increase in population through reproduction –
but that food cannot increase as fast as population can, and
therefore eventuality will allow less food per person, the less
able dying out from starvation or sickness. Thus did Malthus
identify population growth as an obstacle to human progress and
pedalled abstinence and late marriage in his wake. For these
conclusions he came under fire from the Enlightment movement
which interpreted his works as opposing social reform33.
Erasmus Darwin, grandfather of Darwin, was an
unconventional, freethinking physician and poet who expressed his
ardent preoccupation for the sciences through poetry. In the
poem Zoonomia he initiated the idea that evolution of an organism
results from environmental implementation. This coupled with a
strong influence from the similar conclusions of Lamarck shaped
Darwin’s perception on the environment’s inherent nature to mould
and shape evolutionary form34.
METHODS OF SCIENTIFIC DEDUCTION
Early scientists, particularly those in the naturalist field
derived most of their conclusions from observed, unproven
empirical facts. Without the means of logically explaining
scientific theory, the hypothesis was incurred – an educated
guess to be proven through experimentation. Darwin developed his
theory of natural selection with a viable hypothesis, but
predicted his results merely by observing that which was
available. Following Lyell’s teaching, using modern observations
to determine what occurred in the past, Darwin developed theories
that “only made sense” – logical from the point of view of the
human mind (meaning it was based on immediate human perception)
but decidedly illogical from a purely scientific angle. By
perusing the works of Malthus did Darwin finally hit upon his
theory of natural selection – not actually questioning these
conclusions because they fit so neatly into his own puzzle. Early
development of logical, analytic scientific theory did not occur
until the advent of philosopher Rene Descartes in the mid-17th
century (“I think therefore I am”35). Natural selection was shown
to be sadly lacking where it could not account for how
characteristics were passed down to new generations36. However,
it did present enough evidence for rational thought to be applied
to his theory. Thus scientists were able to develop fairly
accurate conclusions with very limited means of divination.
Opposition from oppressive Judeo-Christian church allowed little
room science. Regardless, natural selection became the basis for
all present forms of evolutionary theory.37
LIMITS TO DARWIN’S THEORY
Darwinism, while comparatively rational and well documented
nevertheless upheld the usual problem that can be found in many
logical scientific conclusions – namely deliberate ignorance of
facts which might modify or completely alter years the
conclusions of years of research. Many biologists were less than
convinced with an evolutionary hypothesis that could not explain
the mechanism of inheritance. It was postulated by others that
offspring will tend to have a blend of their two parents
characteristics, the parents having a blend of characteristics
from their ancestors, the ancestors having a blend of
characteristics from their predecessors – allotting the final
offspring impure, diminished desirable characteristics38. Thus
did they believe a dilution of desirable traits evolved even more
diluted desirable traits – these traits now decidedly muted. It
was more than two decades after Darwin’s death that Mendelian
theory of the gene finally came to light at the turn of the
century39. Because of this initial scepticism with Darwin’s
natural selection, when Mendel’s work became widely available
biologists emphasized the importance of mutation over selection
in evolution. Early Mendelian geneticists believe that
continuous variation (such features as body size) hardly factored
in the formation of new species – perhaps nothing to do with
genetic control. Inferences on the gradual divergence of
populations diminished in wake of notions of significant
mutations40.
This gave rise to neo-Darwinian theory in the 1930’s, what
is called “modern synthesis” which encompasses paleontology,
biogeography, systematics and, of course, genetics. Geneticists
have noted that acquired characteristics cannot, indeed be
inherited, while observing that continuous variation is inherited
through the effects of many genes and have therefore concluded
that continuously distributed characteristics are also influenced
by natural selection and evolve through time. Modern synthesis,
in other words, differs little form Darwinian theory, but also
incorporates current understanding of inheritance. Modern
synthesis maintains that random mutations introduce variation
into population, natural selection inaugurating new genes in
greater proportions. Despite revolutionary progress the
discovery of the gene has made, neo-Darwinian theory is still
based on the arbitrary assumption that the primary factor causing
adaptive change in populations is natural selection41.
MORPHOLOGICAL & BIOLOGICAL CONCEPTS
Species have been traditionally described based on their
morphological characteristics. This has proven to be somewhat
premature to say the least: some organisms in extremely
different forms are quite similar in their genetic make-up. Male
and females in many species develop more than a few many
characteristic physical differences, yet are indeed the same
species (imagine that!). Likewise some organisms appear to be
quite morophologically similar but are completely incompatible.
There are many species of budworm moths, all of which are highly
indistinguishable – most of which do not interbreed42.
The idea of species is usually called the biological species
concept, stressing the importance of interbreeding among
individuals in a population as a general description. An entire
population might be thought of as a single unit of evolution.
However similar difficulties arise in attempting a universal
application of this theory. Because morphologically similar
species occur in widely separated regions, it is virtually
impossible to exact whether they could or could not interbreed.
One might ask whether cactus finches from the Galapagos
interbreed – the answer may invariably be yes…but due rather to
the morphological similarities between them. Consider further
asexually producing species, which can be defined by appearance
alone: each individual would have to be defined as different
biological species – a fact which would remain irrelevant. There
are also cases for which no real standard can be applied – the
donkey and horse, for example can mate and produce healthy
offspring, mules which are almost always sterile and therefore
something completely undefinable. Therefore, despite seeming
ideal in its delimitation, the biological species concept cannot
be employed in describing many natural species43. It is
nonetheless a popular concept for theoretical discussions since
it can distinguish which populations might evolve through time
completely independent of other similar populations.
Species classification is therefore not defined by fixed
principles surrounding biological and morphological
classifications both. The random nature of evolution itself is
predictable perhaps only in that one respect: that it remain
virtually unpredictable. In accordance with the Hardy-Weinberg
theory the proportion of irregularity should not necessarily
increase, but because, by its own admission this theory cannot be
employed as a standard but merely to predict results, even it is
limited random un-law of nature44.
BIO-EVOLUTION: POPULATION vs. INDIVIDUALS
According to the theory of evolution, all life or most of
it, originated from the evolution of a single gene. All
relatives – species descended from a common ancestor – by
definition share a certain percentage of their genes. If naught
else than these genes are of a very similar nature. A species
depends on the remainder of its population in developing
characteristics which allow easier adaptability to the changing
environment. These modified genes will ultimately express
themselves as new species or may be passed on to other
populations within a given species. For these traits to be
expressed individually is certainly not going to benefit the
species (ie. the mule retains remarkable traits but cannot
reproduce – they’re also a literal pain in the ass to generate).
Nevertheless should but one individual in a million retain a
beneficial characteristic, opportunity for this to be passed on
is significantly increased. In short order, as per natural
selection highly adapted species can develop where they were
dying out (over centuries to be sure, but dying out nonetheless)
only a (‘n evolutionarily) short span of time ago. Plant
breeders especially know the value of the gene pool. They depend
on the gene pool of the wild relatives of these plants to develop
strains that are well adapted to local conditions (here we refer
to comparatively exotic plants). The gene pool is there for all
compatible species (and that could be a large amount down the
line) to partake of – given the right random conditions and the
future for plant breeders brightens45.
MECHANISMS FOR GENETIC VARIATION
There are a number of known factors are capable of changing
the genetic structure of a population, each inconsistent with the
Hardy-Weinberg principle. Three primary contributing factors are
migration, mutation and selection and are referred to as
systematic processes – the change in gene frequency is
comparatively predictable in direction and quantity. The
dispersive process of genetic is predictable only in quantitative
nature. When species are sectioned into diverse, geographically
isolated populations, the populations will tend to evolve
differently on account of the following accepted standards:
1Geographically isolated populations will mutate
exclusively to their population.
2The adaptive value for these mutations and gene combinations
will differentiate per each population.
3Different gene frequencies existed before the population was
isolated and are therefore not representative of their
ancestors.
4During intervals of small population size gene frequencies
will be fluctuating and unpredictable forming a genetic
“bottleneck” from which all successive organisms will arise46.
Gene frequencies can be altered when a given population is
exposed to external populations, the change in frequency modified
as per the proportion of foreigners to the mainstream population.
Migration may be eliminated between two populations in regions of
geographic isolation, which will isolate in turn, the gene pools
within the population. If this isolation within population
develops over a sufficient span of time the physical differences
between two given gene pools may render them incompatible. Thus
have the respective gene pools become reproductively isolated and
are now defined as biologically different species. However,
speciation (division into new species) does not arise exclusively
from division into new subgroups inside a population, other
aspects might be equally effective47.
The primary source for genetic variability is mutation,
usually the cause of depletion of species’ fitness but sometimes
more beneficial. The ability of a species to survive is
dependent on its store of genetic diversity, allowing generation
of new genotypes with greater tolerance for changing environment.
However, some of the best adapted genotypes may still be unable
to survive if environmental conditions are too severe. Unless
new genetic material is obtained outside the gene pool, evolution
will have a limited range of tolerance for change. Generally
speaking, spontaneous mutations whether they are required or not.
This means many mutations are useless, even harmful under current
environmental conditions. These crippling mutations are usually
weeded out or kept at low frequencies in the population through
natural selection. The mutation rate for most gene loci is
between one in 100 thousand to one in a million. Therefore,
although mutations are the source of genetic variability, even
without natural selection changes in the population would be
unnoticeable and very slow. Eventually, if the only pressure
affecting the locus is from mutation, gene frequencies will
change and fall back to comparative equilibrium48.
The fundamental restriction on the validity of the Hardy-
Weinberg equilibrium law occurs where population size in
immeasurably large. Thus the disseminating process of genetic
drift is applicable for gene frequency alteration in situations
of small populations. In such a situation inbreeding is
unavoidable, hence the primary contributing factor for change of
gene frequencies through inbreeding (by natural causes) is
genetic drift. The larger the sample size, the smaller the
deviation will be from predicted values. The action of sampling
gametes from a small gene pool has direct bearing on genetic
drift. Evidence is observed via the random fluctuation of gene
frequencies per each successive generation in small populations
if systematic processes are not observed as contributing factors.
From this four basic assumptions have been made for idealized
populations as follows:
1Mating and self-fertilization in respective subgroups of
given populations are completely random.
2Overlap of one generation to its successor does not occur
allotting distinct characteristics for each new generation.
3In all generations and lines of descent the number of
possible breeding individuals is the same.
4Systematic factors such as migration, mutation and natural
selection are defunct49.
In small populations certain alleles, perhaps held as common
to a species may not be present. The alleles will have become
randomly lost somewhere in the population in the process of
genetic drift. The result is much less variability among small
populations that among larger populations. If every locus is
fixed in these small populations they will have no genetic
variability, and therefore be unable to generate new adaptive
offspring through genetic recombination. The ultimate fate of
such a population if it remains isolated is extinction50.
GENETIC VARIATION ; SPECIATION
Through genetic variation new species will arise, in a
process termed speciation. It is generally held that speciation
occurs as two given species evolve their differences over large
spans of time – these differences are defined as their genetic
variation. The most popular model use to explain how species
formed is the geographic speciation model, which suggests that
speciation occurs only when an initial population is divided into
two or more smaller populations – via genetic variation through
systematic means of mutation, natural selection or genetic drift
– geographically isolated (physically separated) from one
another. Because they are isolated, gene flow (migration) cannot
occur between the respective new populations51. These “daughter”
populations will eventually adapt to their new environments
through genetic variation (process of evolution). If the
environments of each isolated population are different then they
would be expected to adapt to different conditions and therefore
evolve differently. According to the model of geographic
speciation, the daughter populations will eventually evolve
sufficiently to become incompatible with one another (therefore
unable to interbreed or produce viable offspring). As a result
of this incompatibility, gene flow could not effectively occur
even if the populations were no longer geographically isolated.
The differentiated, but closely related species are now termed
species pair, or species group. Eventually differentiation will
progress far enough for them to be defined as different species.
While divergence is a continuing process, it does not
necessarily occur at a constant rate – fluctuating between
extremely rapid rates and very slow rates of evolution. Two
standard methods have been postulated for the occurrence of
geographic speciation: i) Individuals from a species might
populate a new, isolated region of a give area (such as an
island). Their offspring would evolve geographically isolated
from the original species. Eventually, geographical isolation
from the population on the mainland would evolved distinguishable
characteristics. ii) Individuals might, alternately be
geographically isolated as physical barriers arise or the range
of the species or individuals of a population diminishes52.
However, neither of these forms of speciation through geographic
isolation and consequent individual genetic variation have been
observed or studied direct because of the time span and general
difficulty of unearthing desired fossils. Evidence for this form
of speciation is therefore indirect and based on postulated
theory53.
DARWIN’S FINCHES
The finches of the Galapagos islands provided Darwin with
an important lead towards his development of his theory of
evolution. They were (are) a perfect example of how isolated
populations could evolve. Here Darwin recognized that life
branched out from a common prototype in what is now called
adaptive radiation. There were no indigenous finches to the
islands when they arrived – some adapted to tree-living, others
to cactus habitat, others to the ground. The differentiation was
comparatively small, and yet there evolved fourteen species of
bird classified under six separate genera, each visibly different
only in the characteristics of its beak54.
Joint selection pressure equations have been used to
calculate the change in gene frequency and consequent rate of
mutation resulting from action the of natural selection.
Populations of Galapagos finches arrived at their islands from
South America and were provided with varying methods of
obtainment of sustenance. Only those individuals that evolved
characteristics allowing them to more easily obtain food from
varying sources were not selected against. Populations were
isolated on certain islands and had to adapt to different food
sources. The result was an adaptation to food (seeds) from
trees, ground or cactus-dominated ares. However, the migratory
nature of these finches prompted them to emigrate to alternate
islands, therefore interbreeding with otherwise isolated
populations of finches. The result has been a variation on
single specific characteristics which retain certain properties
due to the singular islands they predominantly occupied. When
the population of immigrants was high enough, the gene pools of
diverse populations of finches presently occupying the island was
modified enough such that offspring would inherit some of the
traits of otherwise isolated finch populations55. Nevertheless,
these finches developed characteristics endemic to their
particular habitat, and because finches tend to remain in groups
rather than individual families, these particular characteristics
became dominant enough to evolve morphologically and later even
biologically different characteristics. These discrepancies
could only lead to greater genetic variation down the line.
Eventually immigrants from the mainland and even other Galapagos
islands were completely incompatible with specific finch
populations endemic to their respective islands56. Generally,
selection pressure decreased as mutations resulting from
systematic processes of genetic variation could no longer occur.
This produced a significantly less versatile gene pool, however,
via genetic drift from individuals of alternate populations who
had, at some point evolved from ancestors the population in
question. Thus the gene pool could be modified without really
affecting the gene frequencies57 – joint pressures were therefore
stabilized, along with the newly developed population.
SPECIATION vs. CONVERGENT EVOLUTION
Speciation is substantially more relevant to the evolution
of species than convergent evolution. Through natural selection
similar characteristics and ways of life may be evolved by
diverse species inhabiting the same region, in what is called
convergent evolution – reflecting the similar selective pressure
of similar environments. While separate populations of the same
species occupying similar habitats may also evidence similar
physical characteristics – due primarily to the environment
rather than their species origin – it should noted that they
progressed form the same ancestor. A defining principle for the
alternate natures of speciation and convergent evolution put
simply: speciation results form a common ancestor, convergent
evolution results from any number of ancestors58.
Morphologically similar populations resulting from the same
ancestor may be compatible and able to produce viable offspring
(if in some occasions not fertile offspring). Morphologically
similar species resulting form different ancestors are never
compatible with one another – even if they are virtual
morphological twins. In fact, morphologically disparate
populations of the same species may be compatible with one
another – whereas those disparate through convergent evolution
would be more than merely incompatible, they may be predator and
prey. Convergent evolution may only account for single specific
physical characteristics of very disparate, unrelated species –
such as the development of flipper-like appendages for the sea
turtle (reptile), penguin (bird) and walrus (mammal)59.
CONCEPT OF ADAPTATION
If individuals were unable to adapt to changes in the
environment they would be extinct in short order. Adaptability
is often based on nuclear inheritance down the generations.
Should an organism develop a resistance to certain environmental
conditions, this characteristic may be passed down through the
gene pool, and then through natural selection be dominant for all
organisms of a given population.
Bacteria are able to accomplish this feat at a remarkably
fast rate. Most, if not all forms of bacteria are compatible
with one another, that is able to exchange genetic information.
The speed at which bacteria reproduces is immeasurably faster
than that of more complex, eukaryote organisms. Bacteria have a
much shorter lifespan as well – but because they can develop very
quickly into large colonies given ideal conditions, it is easier
to understand bacteria in clusters. Should a single bacterial
organism develop a trait that slightly aids its resistance to
destructive environmental conditions, it can pass its modified
genetic structure on to half of a colony in a matter of hours.
In the meantime the colony is quickly expanding, fully adapted to
the environment – soon however, it has developed more than it can
be accommodated. The population will drop quickly in the face of
inadaptability. But that (previosly mentioned) exterior
bacterial organism with the modified trait releases information
yielding new growth, allowing the colony to expand further. It
is generally accepted that bacterial colonies will achieve a
maximum capability – however, through adaptation the bacterial
population will quickly excel once again60. Antibiotics are now
sent to destroy the bacteria. Soon they will be obliterated –
and now all that remains of the colony are a few choice bacterial
organisms. However, an otherwise isolated bacteria enters the
system to exchange genetic information with the much smaller
bacterial colony, conditions are favourable, the bacteria
expands again. Antibiotics are sent again to destroy this colony
– but the exterior bacteria, originating in another organism and
having developed a resistance to this type of antibody has
provided much of the colony with the means for resistance to
these antibodies as well. Once again the bacterial culture has
expanded having resisted malignant exterior interlopers61. This
is how bacteria develops, constantly exchanging nuclear
information, constantly able to adapt to innumerable harmful
sources. As bacteria are exposed to more destructive forces, the
more they decelop resistace to, as surely many of the billions of
bacteria could develop an invulnerability to any threatening
exterior sources given ideal environmental conditions.
PUNCTUATED EQUILIBRIUM
Recently the concept of punctuated equilibrium, as proposed
by American paleontologist Stephen Jay Gould has be the subject
of much controversy in the scientific world. Gould advanced the
idea that evolutionary changes take place in sudden bursts, and
are not modified for long periods time when they are reasonably
adapted to altered environment62.
This almost directly contradicts the older, established
Darwinian notions that species evolve through phyletic
gradualism, that evolution occurs at a fairly constant rate. It
is not suggested by adherents of the punctuated equilibrium model
that pivotal fluctuations in morphology occur spontaneously or in
only a few generations changes are established in populations –
they argue instead that the changes may occur in but 100 to 1000
generations. It is difficult to determine which model could more
adequately describe what transpires over the course of speciation
and evolution due to gaps in fossil-record, 50 to 100 thousand
years of strata often covering deposits bearing fossils. Genetic
make-up need not change much for rapid, discernable morphological
alterations to detected63.
Impartial analysts on the two theories conclude that they
are both synonymous with evolutionary theory. Their primary
differences entail their emphasis on the importance of speciation
in long-term evolutionary patterns in lineage. While phyletic
gradualism emphases the significance of changes in a single
lineage and the revision of species through slight deviation,
punctuated equilibrium emphases the significance of alteration
occurring during speciation, maintaining that local (usually
small) populations adapt rapidly to local circumstance in
production of diverse species – some of which acquire the means
for supplantation of their ancestors and rampant settlement in
many important adaptive breakthroughs64. One must consider that
Darwin was not aided by Mendelian theory. Under such
circumstances Darwin would have surely produced an entirely
different theory for the inheritance of beneficial traits.
Consider that mutations can presumably occur spontaneously, given
the properly modified parent. It can therefore be stated that
punctuated equilibrium is probably a more likely explanation as
it does take into account modern cell, and genetic theory.
Phyletic gradualism, while certainly extremely logical is a
theory which simply cannot encompass those circumstance in which
significant change is recorded over comparatively short periods
of time. Both are complementary to be sure, but perhaps one of
the two distorts this complementary nature formulating inaccurate
assumption.
VALUE/LIMITATIONS: THE THEORY BIOLOGICAL EVOLUTION
Whether or not the theory of evolution is useful depends on
whether or one values progress above development of personal
notions of existence. Certainly under the blanket of a
superficial American Dream one would be expected to subscribe to
ideals that society, that the state erects. Of course, these
ideals focus on betterment of society as a whole – which now
unfortunately, means power to the state. Everybody is thus
caught up in progress, supposedly to “improve the quality of
life”, and have been somewhat enslaved by the notion of work.
Work has become something of an idol, nothing can be obtained
without work – for the state. Whether one agrees with the
thoughtless actions of the elite or not, people are oppressed by
conforming to ideals that insist upon human suffering. Some
irresponsible, early religious institutions did just that,
erecting a symbol of the people’s suffering and forcing them to
bow before it. Development of aeronautic, or even cancer
research contributes primarily to this ideal of progress.
Development of such theories as biological evolution, contribute
nothing toward progress. It instills in the people new
principles, to dream and develop an understanding of themselves
and that which surrounds them ones, freeing their will from that
shuffling mass, stumbling as they are herded towards that which
will reap for them suffering and pain. The state provides this
soulless mass with small pretty trinkets along the way, wheedling
and cajoling them with media images of how they should lead their
lives – the people respond with regrets.
Modern theory of biological evolution is actually sadly
lacking in explanation for exactly how characteristics are passed
down to future generations. It is understood how nitrogen bases
interact to form a genetic code for an organism – but how the
modification that the organism develops, occurs is unknown.
Somehow the organism mutates to adapt to environmental
conditions, and then presumably the offspring of this organism
will retain these adaptations65. Of course, biological evolution
cannot also explain precisely how first organisms developed:
Generally, the theory accounts for energy and chemical
interactions at a level consistent enough to establish a constant
flow of said interactions – but even here it falls short. And
what of phyletic gradualism? It is completely unable to explain
the more sudden mutations that occur…for obvious reasons it
cannot explain this (Darwin had no knowledge of genetics), but
even punctuated gradualism doesn’t balance this problem. I’m
sure there are numerous other problems which can be addressed but
these can be dealt with where opinion can be more educated.
ALTERNATE EXPLANATIONS OF BEING
Man it would appear, has always sought meaning for his
existence. Development of many theories of existence have been
conceived and passed down through the ages. Institutions
conferring single metaphysical and elemental viewpoints have been
established, some of which have been particularly irresponsible
and oppressive towards the people they were supposed to
“enlighten”. Most religious institutions have been used as
political tools for means of manipulation of the masses, going
back to early Roman days when empower Augustus absorbed
Christianity into the Roman worship of the sun, Sol Invectus, as
a means of subjugating the commoners to Roman doctrine.
Generally religious institutions have exploited the people and
have been used as excuses for torture, war, mass exterminations
and general persecution and oppression of the people it pretends
to serve, telling the people they must suffer to reach ultimate
transcendent fulfilment. Unfortunately this oppression continues
in today’s modern – even Western – world. There have actually
been almost innumerable explanations for the physical presence of
man – these explanations merely been suppressed by the prevailing
religious institutions for fear that they will be deprived
absolute power over the people…they’re right.
CONCLUSIONS
Without Darwin it can be concluded, reasonable
interpretation of biological evolution simply would not be.
Natural selection, the process determining the ultimate survival
of a new organism, remains the major contributing factor to even
the most modern evolutionary theory.The evolutionary process
spans over the course of hundreds of thousands of generations,
organisms evolving through systematic and dispersive mechanisms
of speciation. Recently, heated debate surrounding whether
characteristics are passed on in bursts of activity through
punctuated equilibrium or at a constant rate through the more
traditional phyletic gradualism66. The release of Mendelian
theory into the scientific community filled the primary link
missing in Darwin’s theory – how biological characteristics were
passed on to future generations. Applications of genetic theory
to evolutionary theory however, are somewhat limited. It is
difficult to classify all species even through modern means of
paleontology and application to the theory of organic evolution.
BIBLIOGRAPHY
1Brent, Peter. Charles Darwin, A Man of Enlarged Curiosity.
Toronto: George J. McLeod Ltd., 1981.
2Dawkins, Richard. The Selfish Gene. New York: Paladin,
1978.
3Farrington, Benjamin. What Darwin Really Said. New York:
Shoken Books, 1966.
4Gailbraith, Don.Biology: Principals, Patterns and
Processes. Toronto: John Wiley and Sons Canada Ltd.
1989, Un. 6: Evolution.
5Glass, Bently. Forerunners of Darwin 1745-1859. New York:
Johns Hopkins Press, 1968.
6Gould, S.J. Ever Since Darwin. New York: Burnett Books,
1978.
7Grolier Encyclopedia, New. New York:
Grolier Publishing, Inc., 1991.
8Haldane, J.B.S. The Causes of Evolution. London:
Green and Co., 1982.
9Leakey, Richard E.. Mankind and Its Beginnings. New York:
Anchor Press/Doubleday, 1978.
10Miller, Johnathan. Darwin For Beginners. New York:
Pantheon Books, 1982.
11Moore, Johh A. Heredity and the Environment. New York:
Oxford University Press, 1973.
12Patterson, Colin. Evolution. London: British Museum of
Natural History Press, 1976.
13Random House Encyclopedia, The. New York:
Random House Inc., 1987, p. 406-25.
14Ridley, Mark. The Essential Darwin. London, Eng:
Allen & Unwin, 1987.
15Smith, J.M. On Evolution. London: Doubleday, 1972.
16Stansfield, William D.. Genetics 2/ed. New York:
McGraw-Hill Book Company, 1983, p.266-287.
17Thomas, K.S.. H.M.S. Beagle, 1820-1870. Washington:
Oxford University Press, 1975.
ENDNOTES
_______________________________
1. Johnathan Miller, Darwin for Beginners,
New York, Pantheon Books, 1982, p. 8.
2. Mark Ridley, The Essential Darwin, London Eng:
Allen & Unwin, 1987, p. 23.
3. J.M. Smith, On Evolution, London, Eng.:
London/Doubleday, 1972, 48.
4. Peter Brent, Charles Darwin, A Man of Enlarged
Curiosity, Toronto: George J. McLeod Ltd., 1981, p. 313.
5. Don Gailbraith, Biology, Principals, Patterns and
Processes, Toronto: John Wiley and Sons Canada Ltd.
1989, Un. 6: Evolution, p. 403.
6. opsit., p. 92.
7. opsit., p. 96.
8. J.B.S. Heldane, The Causes of Evolution, London:
Green and Co., 1982, p. 237.
9. ibid., p. 444.
10. Benjamin Farrington, What Darwin Really Said,
New York: Shocken Books, 1966, p. 52.
11. ibid., p. 61.
12. opsit., p. 405-06.
13. opsit., p. 383.
14. ibid., p. 390.
15. ibid., p. 388.
16. ibid., p. 381.
17. John A. Moore, Heredity and the Environment,
New york: Pantheon Books, 1980, p. 141.
18. opsit., p. 417.
19. opsit., p. 385.
20. K.S. Thomas, H.M.S. Beagle, 1820-1870,
Washington: Oxford University Press, p. 229.
21. opsit. p. 80
22. opsit., p. 262.
23. ibid., p. 536.
24. opsit., p.417.
25. opsit., p. 183.
26. opsit., p. 419.
27. The Random House Encyclopedia, New York:
Random House Inc., 1987, p. 432.
28. ibid., p. 437.
29. opsit., p. 348.
30. The New Grolier Electronic Encyclopedia,
Grolier Electronic Publishing, Inc., 1991,
MALTHUS.
31. opcit., p. 403.
32. ibid., p. 404.
33. opsit., MALTHUS.
34. opsit., p. 309.
35. opsit., p. 841.
36. Bently Glass, Forerunners of Darwin 1745-1859,
New York: Johns Hopkins Press, 1968.
37. opsit., p. 351.
38. Richard E. Leakey, Mankind and Its Beginnings,
New York: Anchor Press/Doubleday, p. 177.
39. ibid., p. 156.
40. opsit., p. 218.
41. opsit., p. 408.
42. opcit., p.431.
43. ibid., p. 432/
44. opsit., p. 253.
45. ibid., p. 554.
46. William D. Stansfield, Genetics 2/ed,
New York: McGraw-Hill Book Company, 1983, p. 266.
47. ibid. p. 269.
48. opsit., p. 272.
49. ibid., p. 274.
50. ibid., p. 275.
51. opsit., p. 434.
52. ibid., p. 432.
53. ibid., p. 435.
54. opsit, p. 420.
55. opsit., p.374.
56. ibid. p. 421.
57. opsit., p. 299.
58. opsit., p. 160.
59. opsit., p. 412.
60. opsit. p. 138.
61. ibid. p. 95.
62. opsit., p. 441.
63. ibid., p. 441-2
64. ibid., p. 443.
65. opsit., p. 572.
66. opsit., p. 441.
