What exactly is evolution? I’m sure this question is in your mind. Well, biological evolution would be defined as a process that results in heritable changes in a population spread over many generations. It is important to realize that evolution does not concern simply one individual (Moran).
I’m sure you have heard many theories of how the complex human being and other species actually ended up on earth. For many years, the only explanation we could give ourselves was the theory that some higher power, like a god, created complex beings on Earth. It wasn’t until Charles Darwin came along that people could explain their existence with a science explanation, evolution.
Darwin’s theory had a total of five main points. His first point was that species are extremely fertile. They make more offspring then can actually grow to be a full adult. For example, human females have thousands of eggs that can produce adult offspring, but few of those eggs will actually make it to adulthood. His second point was that populations remain at roughly the same size. Darwin’s third observation was that food resources may be limited but they remain constant most of the time and available. From these three observations Darwin inferred that there could be a simple struggle for survival among the individuals it concerns (Huxley).
Darwin’s fourth point was that when two individuals who produce offspring sexually are not identical. Generally, they vary in many ways. His last point of the five was that much of this variation is heritable. From all these five points put together Darwin inferred that “In a world of stable populations where each individual must struggle to survive, those with the ‘best’ characteristics will be more likely to survive, and those desirable traits will be passed to their offspring.” (Huxley). These “strong” traits that survive through many generations become dominant traits. This is called natural selection. With natural selection it call also be said that these dominant traits can change a population over time, as well as creating new species.
Darwin believed that all species today derived from a single species back in the ancient times. DNA evidence also supports this idea as well.
Unlike Darwin, Jean-Baptiste Lamarck’s scientific theories were much ignored. "Lamarckism" or "Lamarckianism" is refered to today as the idea of traits being inherited (Waggoner). What Lamarck thought was much more in depth then Darwin or any other early evolutionary philosophers. He thought that changes in the environment causes changes in the organisms needs, which causes a change in the organism’s behavior. The behavioral change leads to a change in the way they use certain structures of their body. This changes the size of the structure in time. This is what Lamarck called his first law when he wrote his book. Lamarck’s second rule was that all changes in the organism were object to change by heredity (Waggoner).
Lamarck’s theory was much different from Darwin’s. Although, is presents much of the same ideas. Some of the evidence written in Lamarck’s book was evident in Darwin’s. He even states the idea of natural selection into his books like Darwin, but seems to leave this idea as less important. His ideas also differ a lot from today’s idea of evolution. He thought that evolution created perfection over a long period of time (Waggoner).
There is much more to Lamarck and Darwin’s theories then it just being a theory. Many conclusions came from their theories and people began to research. One thing that is highly researched is micro evolutionary mechanisms. Micro evolutionary mechanisms would include mutation, migration, genetic drift, and natural selection.
Mutation is explained when a random red gene is mutated into a blue gene. This can not be explained for all genetic changes but it is used for some. Migration or gene flow is when a certain gene that isn’t in an area migrates to another area. This increases a chance of the new gene combining with the gene that already exists in this area. Genetic drift is explained easily. It would be when two different dominant genes mate. The offspring gets the luck of getting more of gene then the other in the offspring. If 80% of the offspring carry one gene instead of the other, the genetic drift is shifted to the gene with the most offspring carrying it. Natural selection, which I have talked about earlier in Darwin’s theories, is when the “strong” gene survives through an amount of time within a certain species. (Caldwell).
Another level of evolution is Macroevolution. Macroevolution deals with Speciation. Speciation is the process of a single species becoming two or more species. Some biologists say that macroevolution can not occur without speciation. This level of macroevolution has been tested within plants and within 50 to 60 years the single species of the plant had became two species. Another level of macroevolution would be extinction. The reasons for extinction are numerous and it is the fate of all species. This leads into mass extinction. The last level would be punctuated equilibrium. This would be an inference about the process of species dated back to the fossil era. This says that each species will go through little evolutionary change in it’s’ history record. This leaves the sexually reproducing species in a stage called stasis.
When scientists study evolution they also study embryology. This is the study of an embryo. It includes the fertilization stage all the way to the fetus stage. This is important because evolutionary philosophers need to know what the embryo starts out at and what genes it carries. It may also be important to compare past embryos to current growing embryos to compare change.
Another thing that is very important in evolution is comparative morphology. This deals with the study of the structure of organisms. They study the outward appearance of the body such as structure. They also study the inward structure which would include things like bones. This helps include evidence for evolution because with this study, they can track physical structural changes of each species. If it changes, this gives evidence that evolution actually happens.
Another big part of evidence for evolutionary change would be the fossil record.
For 300 years scientists have been collecting fossils for evidence. This is the first record, and best, that records changes within a species over a long amount of time. Fossils provide a wide time range that scientists can study the changes of past life and compare them to current life. This gives them more time to study the differences that have evolved in each species found. Charles Darwin even used evidence from the fossil record to put into his theory.
Taking all this evidence into strong consideration, I can honestly say that evolution has a lot of scientific evidence to back up the theory. The one thing that makes me want to believe that evolution exists is natural selection. When studying DNA and how it works, I found out that the strong, dominant genes are the ones who definitely survive. If you take three genes and create offspring with the three, the strongest one will survive. Within time the weakest gene will slowly vanish. This will create a change from the past individual in the species. If you get a gene stronger then the dominant one that survived, the species will change and keep that dominant trait instead of the first strongest gene.
The second thing that makes me want to back up the theory of evolution would be the fact that Darwin and other scientists like Lamarck had so much evidence to support their theories. Darwin even used the Fossil Record for evidence. If scientists were already on a track of figuring out what Darwin’s theory proposed, then maybe what he is saying is true.
Of course, with everything, people will develop their own opinions. I don’t believe that one certain theory will ever be accepted by everyone as whole, if that would be evolution or creation from a higher being. There is evidence to support evolution and maybe their will be another evolutionary philosopher to support Darwin’s theory and make a big break in evidence to figure out the real answer of how we ended up on this lovely earth. Until then, you have to decide on your own what you honestly believe!
Bibliography
Huxley, Thomas. "Charles Darwin: The Theory of Evolution." On Truth & Reality: Philosophy Physics Metaphysics of Space, Wave Structure of Matter. Famous Science Art Quotes. Web. 11 May 2011. http://www.spaceandmotion.com/Charles-Darwin-Theory-Evolution.htm.
Waggoner, Ben. "Jean-Baptiste Lamarck (1744-1829)." Web. 11 May 2011. http://www.ucmp.berkeley.edu/history/lamarck.html
Moran, Laurence. "What Is Evolution?" 22 Jan. 1993. Web. 11 May 2011. http://www.talkorigins.org/faqs/evolution-definition.html.
Caldwell, Roy. "Evolution 101: Microevolution." Understanding Evolution. National Center for Science Education. Web. 11 May 2011. http://evolution.berkeley.edu/evosite/evo101/IVBMechanisms.shtml.
"Mechanisms of Macroevolution." Ecology and Evolution. Web. 11 May 2011.
