Download 1 Elisa Walker Mr. Mecham Biology B Period 1

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Elisa Walker
Mr. Mecham
Biology B
Period 1
December 12, 2013
Theory of Natural Selection
The quote, “Multiply, vary, let the strongest live and the weakest die” was quoted
by Charles Darwin in his book titled The Origin of Species. Charles Darwin is a very
important figure in science, and he changed the world with his discoveries. Darwin paved
the way for the embarkation of understanding evolution and its mysteries. He was the one
who proposed the theory of natural selection. In order to understand Charles Darwin and
the theory of natural selection with greater understanding, we must know what Darwin’s
theory states, look at some of the evidence used to support his theory, and gain some facts
about the difficulties the curious scientist ran into while developing his theory.
In the Holt McDougal Biology book, natural selection is defined as, “A
mechanism by which individuals that have inherited beneficial adaptations produce more
offspring on average than do other individuals.” Darwin proposed that natural selection
was made up of four main principles. Those main principles are: variation,
overproduction, adaptation, and descent with modification. The process starts with
variation; it is simply the differences in inherited traits within a population.
Overproduction is the next step involved in evolution. It is the competition between
offspring. It takes place when too many organisms are produced for the environment to
support them. That is when Adaptation comes in. Adaptation gives an organism an
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advantage or disadvantage in an environment. The organism that has the advantage and is
more fit, will survive. Descent with modification is the last step when that advantage is
passed down to the offspring and will change the species over time. All of this is part of
the process of evolution, and it backed up Darwin’s idea that all organisms share a
common ancestor.
Just like any theory, Darwin needed evidence to back up his ideas. Luckily for
him, Darwin was able to gather a lot of evidence on his explorations to the Galapagos
Islands and South America. Fossils, geography, embryology, and anatomy are all four
main evidences Darwin used to back up his theory that all species come from a common
ancestor. Scientists knew about fossils and how they changed even before Darwin, but
the discoveries they made only supported the concept of descent with modification even
more. Charles saw geography take place on some islands near South America. He noticed
that some species on the islands closely resembled some species on the mainland. He was
able to hypothesize that at some time the species on the mainland migrated to the islands.
The slight changes he saw in the species were just a result of the individuals being
favored in their environment. Examples of this are the finches he discovered on the
Galapagos Islands. He noticed that they all shared the same ancestor from the mainland
of South America. They had changed only to adapt to their environment. Charles Darwin
was the first scientist to establish the principle of biogeography, the study of the
distribution of organisms around the world. The next evidence Darwin used was
embryology. It is when larvae can be almost identical to each other, but it develops into
completely different organisms. Barnacles and crabs fascinated him for this reason. They
are identical as larvae, but they develop into something that isn’t even close to each other.
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This was more evidence that all organisms must have come from the same ancestor. The
last one, anatomy, is simply the structure of living things. In this he found homologous
structures and vestigial structures. Homologous structures are features that are similar in
structure but appear in different organisms and have different functions. An example of
this is a human hand and a mole foot. Even though they provide different functions, they
both have a similar bone structure. The only way to explain this phenomenon is again,
that we all share a common ancestor. Vestigial structures are yet another way to prove
Darwin’s theory. They are remnants of organisms or structures that had a function in an
earlier ancestor. We see this all around us. Whales have pelvic bones which can lead us to
believe that whales were once land mammals. We even see this is humans! Our tailbones
and appendixes are all perfect examples of vestigial structures.
Even with all of his evidence, it was not easy for Charles Darwin to develop his
theory. He was a genius man, but he was also human. Throughout his life Charles
suffered from sickness, the death of a loved one, frustration of unanswered questions, and
many more. Just like us today, Darwin had to wait to receive answers to some of his
questions. For example, Darwin could not understand how organisms adapted to their
environments until he read the writings of Thomas Malthus. The writings of Malthus
showed how the human population could double its size in twenty-five years, but it never
did because of disease and overproduction. Charles realized that the same things happen
in nature. However, all of these problems were miniscule compared to the biggest
complication of them all. That complication is the Christian Church. Everyone in the
1800’s believed in God and his creations. The people did not want to believe that new
species could show up on earth without God putting them there. Their religion was the
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explanation of how they got to earth, and they never gave much thought to it after that.
They didn’t like Darwin’s ideas because it completely went against their faith. They
were also offended when Darwin proposed that humans evolved from chimps. The Bible
says that man was created in God’s image, and mankind didn’t want to believe that they
were just another part of natural selection. Because of this, the poor scientist was
ridiculed and mocked for his ideas continuously. He only had a few supporters to agree
with his theories, and they were completely outnumbered. The controversy never ended
in his lifetime, and it still exists in our lives today.
As you can see, there are a lot of factors that go into the theory of natural
selection. After learning more about what his theory states, some evidences he used to
back up his theory, and difficulties he ran into, I have found that I agree and disagree
with some of his ideas of evolution. I agree that evolution takes place on the earth today,
as well as natural selection. This is evidently seen in bacteria and other organisms we can
study in small amounts of time. To the extent that all organisms share the same common
ancestor, I do not completely agree. I am a member of a Christian Church, and I too
believe in God. I believe that it isn’t a same common ancestor, but a same common
creator. I believe that God has his ways of running things, and that man can’t completely
comprehend his plans. The theory of natural selection is just that. It is a theory. We have
a lot of missing information in order to completely prove evolution. My opinion is that
evolution happens, but that it is all controlled by God. What others will believe is their
own opinion. Charles Darwin was a scientist who changed the world with his theory of
natural selection. His theory will always be seen as right in the eyes of one, but wrong in
the eyes of another.