Most Controversial Of Darwin's Theory example essay topic

Theory That Shook The World Other than Mendelson 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 ofnatural 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 inDarwin's theories, he astounded the scientific world as well asthe 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 wasa 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 hew as 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's he sent his son to medical school at Edinburgh instead (Bowler p 62).

While Darwin wast here, he could not keep his mind on his medical studies and decided to go and study at the University of Cambridge and become clergyman. It was here that he was to meet two people who would change his future forever; Adams Sedgwick and John StevensHenslow. Out of these two, Hens low 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, Henslowsuggested that he go on the Beagle as an unpaid naturalist on the scientific expedition (GEA & RBi p 43).

Darwin gladly tookHenslow'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 thepublic. 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), onthe 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 tobe 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 catatropisttheory.

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 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 head 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 & RBi-2 p 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 thedefinition 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 thepublic as a way to produce the necessary end but Darwin held its important evidence of evolution accessible for all to witness. And to back up this finding in the domesticated breeds as well asthe wild he came up with his variability within a species.

Thedefinition 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 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 ofnatural 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 away 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 ofa 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, the yare 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 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 anew 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 tothe 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 on eof 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)..