, Research Paper
The Theory That Shook The World
Other than Mendellson and his studies with genetics,
Darwin has by far contributed the most to our modern science.
From his theories on variation of species to his explanation of
natural selection Charles Darwin has shocked the world by proving
the world older than previously thought and creatures not
immutable. In this present day these theories are as common
belief as a simple mathematical equation such as two plus two
equals four; but in the year eighteen hundred and fifty nine
Darwin not only risked his reputation with these far fetched
findings but also the risk of being excommunicated from the
church. Previous to Darwin the thought had been that the world
itself was only a few hundred years old and that all creatures
were made by God in those seven days as they lived exactly today
(Campbell p 421). Aside from past resistance, Darwin also comes
under scrutiny still today as missing fossils which are to have
been the bridge between a two familiar species are not yet found
(Hitching p 3). Whatever the reason of belief or disbelief in
Darwin’s theories, he astounded the scientific world as well as
the public and was able to convince many in the presence of a
misguided past belief. This fact alone makes him one of the most
important people of science ever.
Charles Darwin was born in Shrewsbury-Shropshire,
England on Feb 12, 1809 (GEA & RBi p 42). He was the fifth child
in a wealthy English family with a history of scientific
achievement with his paternal grandfather Erasmus Darwin who was
a physician and a savant in the eighteenth century (GEA & RBi p
42). As a young boy Darwin already showed signs of his love for
nature. When he was not reading about nature and its quirks he
was out in the forest looking for wild game , fish, and insects
(Campbell p 424). His father, although noting his son’s interest
in nature, felt that all the discoveries of the natural branch of
science had been accomplished so he sent his son to medical
school at Edinburgh instead (Bowler p 62). While Darwin was
there, he could not keep his mind on his medical studies and
decided to go and study at the University of Cambridge and become
a clergyman. It was here that he was to meet two people who
would change his future forever; Adams Sedgwick and John Stevens
Henslow. Out of these two, Henslow turned into his second father
and taught him to be meticulous in his observations of natural
phenomena (GEA & RBi p 42). Upon graduating in 1831, Henslow
suggested that he go on the Beagle as an unpaid naturalist on the
scientific expedition (GEA & RBi p 43). Darwin gladly took
Henslow’s advice and set out on his voyage to South America to
analyze and collect data that would later back up his
evolutionary theories (Campbell p 424).
Even as Darwin collected his data pertaining to what
would become his theory on natural selection, many pre-existing
views still had a hold on the scientific world as well as the
public. The earliest recorded were those of Plato and Aristotle.
Plato (427-347 BC) believed in two worlds; an illusionary which
was perceived only through our senses and a real world which was
ideal and eternal (Campbell p 422). Aristotle (384-322 BC), on
the other hand, believed in a “scala naturae” in which each being
has its own rung on a ladder which was permanent (Campbell p
422). Also, there were the present religious views that had to
be dealt with as well as the ancient ideals. At that time many
believed that animals and plants did not evolve because they were
made holy and immutable by God on those seven days (GEA & RBi p
43). A person who was widely respected and also took some
beliefs from Aristotle and present religion was Carolus Linnaeus
(1707-1778). He believed species immutable and later became
known as the father of modern taxonomy (Campbell p 422). Perhaps
the largest barrier Darwin had was to convince the present day
scientists of his findings in contrast to their pre-existing
theories. The most common of the time was the catatropist
theory. The definition of this theory was that “a violent and
sudden change in the earth” had destroyed all creatures and each
time this happened, God would come back down and recreate all the
life in a seperate seven days (Webster p 131). This theory in
itself seemed created for the soul purpose of covering up the
reason for fossils existing and misled thought of the species
being immutable (Campbell p 423).
After Darwin’s voyage on the Beagle, he had begun to
develop his own theory of evolution. His personal definition of
evolution was “in biology, the complex of processes by which
living organisms originated on earth and have been diversified
and modified through sustained changes in form and function” (JWV
p 20). In regards to his research he had not only found
evolution in the wild but in the domesticated sphere as well.
Darwin held that all related organisms descended from a common
ancestor and he found examples easily in common life (GEA & RBi p
43). One of these such examples were the domesticated pigeon.
Darwin studied the skeletal and the live forms of the pigeons he
had found. In doing so, he found them all to be related but for
a small change in their phenotype. Phenotype being defined as
follows “the actual appearance of an organism” (GEA & RB
77). This small difference had been procured through the use of
breeding and mutation. Perhaps the most notable would be the
number of feathers in the fantail which ranged from twelve to
forty feathers (Darwin p 42). Another example Darwin found in
speciation by domesticated breeding were cows and horses. By the
definition of a gene pool, “large random assortment of genes that
may be rearranged”, the farmers were able to produce a better
breed of race horse or milk cow by breeding the best he had
together (JWV p 21). This sexual evolution was just seen by the
public as a way to produce the necessary end but Darwin held it
as important evidence of evolution accessible for all to witness.
And to back up this finding in the domesticated breeds as well as
the wild he came up with his variability within a species. The
definition to variability within a species held that 1) the
offspring resemble the parents , but were not identical and 2)
some differences in the parents were due solely to the
environment but were often inheritable (JWV p 20). These two
statements as well as the backup with clinical data helped to
show that his theory was correct.
Another area of variability was that of species in the
wild. Perhaps Darwin’s most famed findings to back his theory
are “Darwin’s finches”. During his voyage on the Beagle he had
observed thirteen different types of finches (Campbell p 425).
These finches were found on seperate Galapagos Islands. Here
each species of finch had at one time migrated to another island.
In doing so the founder effect had been put into action. The
founder effect being described as “when a few individuals of a
population migrate and form a new colony having only a small gene
pool causing a new species” (JWV p 23). Due to the diverse
surroundings and limited gene pool the thirteen species had
evolved from the original species that had migrated from the
mainland to the islands. Darwin also observed other animals on
these islands that were not found anywhere else in the world and
began to doubt the churches teaching that species were immutable
(Darwin p 29).
The most controversial of Darwin’s theory was that of
natural selection. The term evolution was so controversial even
Darwin did not use it but the phrase “origin of species” instead
(Darwin p 27). Even though he did not term it evolution his
views were definitely concrete and were laid out in a few simple
sentences. These were the reasons why natural selection was a
way of life and always had been. First, Darwin proposed that
food supply was too little to support the large population thus
eliminating those who were not strong enough to find food and
survive. Second, parents adapted to a certain environment well
would pass on favorable traits that would help the next
generation survive, those without the trait would not survive.
Third, each generation would become better adapted and if
remaining in the same environment would become more capable of
surviving. Finally, even with all the above working there were
also factors of mutation, genetic drift, and bottle neck theories
which contributed to the survival of the fittest (GEA & RBi p
43). Mutation being the most effective in changing a species had
four factors by itself: 1) size of a population, 2) the length of
a generation’s life span, 3) the degree to which the mutation was
favorable, and 4) the rate at which the same mutation appears in
descendants (JWV p 21). Although most mutations are fatal, they
are key in changing the genetic make up of an individual.
Genetic drift is described as when a species for some reason
begins to drift apart or come together to create a new specie or
species. This is typically seen in today’s fossil record when a
present species is related to an extinct animal. [see fig. 1]
Another of the traits of natural selection is the bottle neck
theory. Here a population has been destroyed to such an extent
that only a few survive. This limited population will recreate a
new species based on its extremely limited gene pool and have a
higher chance of carrying a fatal gene. All these factors
working together simultaneously create the phenomena of natural
selection.
Darwin was not going to publish his findings but was
forced to by a young man Alfred Russel Wallace who had come to
the same conclusion after twenty years had passed. Although both
scientists names were on the original copies of the Origin of
Species Wallace regarded Darwin as the soul author. Within a
year of writing, Darwin published what would be twenty years of
research in 1859. Although, thoroughly backed up with
painstaking research, it was still refereed to as “the book that
shook the world” and in its first day of sales had sold out (GEA
& RBi p 43). The immediate reaction in the science world was one
of disbelief. The leading scientists of the day said that Darwin
could not prove his hypothesis and the concept of variation could
not be proved. Darwin was to be doubted for the next seventy
years until the rediscovery of Mendel’s pea plant experiments
(GEA & RBi p 43). With these new findings on genetics, many
scientists would take in account Darwin’s work. Some of these
people were to be a German zoologist named Ernst Mayr, a botanist
G. Ledyard Stebbins, and paleontologist named George Simpson
(JWV p 21).