Title of Paper : Theory of Evolution

Grade Received on Report : 87



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 ever .

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 interpret ).

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) , but wide-

range acceptance of this idea, beyond the bounds of the scientific community, did not arise until Darwin

published his findings in 1958 . 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 growth . 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 puzzle . For fear of contradicting his father's beliefs, Darwin did not publish his

findings until he was virtually forced after Alfred Wa!

llace 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) , 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

individuals . 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 al!

so increase proportionately, generally maintaining comparatively stable population .

Twelve years later, Darwin published