Evolution Essay, Research Paper

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: 1 Variation 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.

2 The 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.

3 The only variations pertinent to evolution are those which are

inherited.

4 Evolution is an ongoing process which must span many moons to become

detectably apparent.

5 Complexity of a species may not necessarily increase with the

evolutionary process – it may not change at all, even

decrease.

6 Predator 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: 1

Geographically isolated populations will mutate exclusively to their

population.

2 The adaptive value for these mutations and gene combinations will

differentiate per each population.

3 Different gene frequencies existed before the population was isolated

and are therefore not representative of their ancestors.

4 During 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: 1 Mating and self-fertilization in respective

subgroups of given populations are completely random.

2 Overlap of one generation to its successor does not occur allotting

distinct characteristics for each new generation.

3 In all generations and lines of descent the number of possible

breeding individuals is the same.

4 Systematic 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.

1 Brent, Peter. Charles Darwin, A Man of Enlarged Curiosity.

Toronto: George J. McLeod Ltd., 1981.

2 Dawkins, Richard. The Selfish Gene. New York: Paladin,

1978.

3 Farrington, Benjamin. What Darwin Really Said. New York:

Shoken Books, 1966.

4 Gailbraith, Don. Biology: Principals, Patterns and Processes.

Toronto: John Wiley and Sons Canada Ltd.

1989, Un. 6: Evolution.

5 Glass, Bently. Forerunners of Darwin 1745-1859. New York:

Johns Hopkins Press, 1968.

6 Gould, S.J. Ever Since Darwin. New York: Burnett Books,

1978.

7 Grolier Encyclopedia, New. New York:

Grolier Publishing, Inc., 1991.

8 Haldane, J.B.S. The Causes of Evolution. London:

Green and Co., 1982.

9 Leakey, Richard E.. Mankind and Its Beginnings. New York: Anchor

Press/Doubleday, 1978.

10 Miller, Johnathan. Darwin For Beginners. New York:

Pantheon Books, 1982.

11 Moore, Johh A. Heredity and the Environment. New York:

Oxford University Press, 1973.

12 Patterson, Colin. Evolution. London: British Museum of Natural

History Press, 1976.

13 Random House Encyclopedia, The. New York:

Random House Inc., 1987, p. 406-25.

14 Ridley, Mark. The Essential Darwin. London, Eng:

Allen & Unwin, 1987.

15 Smith, J.M. On Evolution. London: Doubleday, 1972.

16 Stansfield, William D.. Genetics 2/ed. New York:

McGraw-Hill Book Company, 1983, p.266-287.

17 Thomas, 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.