Evolution!!!
Evolution is the change of a trait in a species over long periods of time, that causes a lot of diversity in organisms. Many people have different theories about evolution but one of the most well respected of those people is Charles Darwin. Charles Darwin had the belief that all organisms evolved over time from a common ancestry. He believed this happened using “Natural Selection”. Natural Selection is when traits become more or less common in a population based on the needs of the organisms to survive and reproduce. Natural Selection affects the phenotype of an organism or the visible traits. After a while an organism will adapt and gain certain characteristics that help with specific tasks. That trait will be more observable in the offspring of the organism. Evolution can end up changing one species into 2 differently species entirely. Charles Darwin first created his theory of Natural Selection from being on a 5 year cruise, in which he noticed a diversity in wildlife and fossils. He looked into it more and after more research, received an essay from Alfred Russel Wallace describing the same basic idea that he had about Natural Selection, and saying that he wants to combine ideas. Darwin then began examining the origin of humans, and sexual selection which determines what traits an organism gets. Darwin later published multiple books on the subject. Darwin died on April 19, 1882.
Another person well known for their research on evolution is Jean-Baptist Lamarck. Lamarck was in the military and got an award for bravery, but returned from war because of an injury. After getting back he decided to continue pursuing a career in medicine. He realized that he had an interest for botany, and wrote a 3 volume set of books about flowers. He was later appointed the position of professor of zoology. He then started studying evolution and came up with the idea of “Inheritance of acquired characteristics”. There were two basic theories behind it. One was the theory that body parts that are used grow bigger and stronger, where body parts that aren’t used slowly waste away and disappear. The other was that any changes that occur in somethings lifetime will be passed down to their children. Both of these scientists had ideas that involved the theories Microevolution and Macroevolution.
Microevolution is a change in gene frequency over a certain amount of time. Even though the number of alleles in an environment never stays the same, the frequency is usually around the same area. There are many different parts to micro evolution, and one of those factors is mutation. Mutation is a change in an organism's DNA sequence in a cell’s genome, that affects the way it looks and behaves. Mutations are caused by radiation and viruses. A lot of errors also occur during DNA Replication, during the polymerization of the second strand of DNA. Errors like these are known as mutations and can have serious affects on the phenotype of an organism. Natural selection is another part of Microevolution. Natural selection is where an organism’s phenotype adapts to the environment to help survival and reproduction. Genetic drift is part of microevolution also. Genetic drift is when there is a change in the frequency that an allele appears in a population due to random chance.This being the case, the organism will receive a random allele from the parents, so it’s almost all chance whether or not a population will be able to keep that allele. And yet another big part of microevolution is migration. Migration is when an organism moves in or out of a population. This seriously affects things because it brings in different genes that the population didn’t have before, and it also changes the frequency of the alleles of the population. Microevolution is a major part of evolution. There are other parts to evolution other than microevolution though.
Macroevolution is the part of evolution that explains changes made over an extremely long period of time. Macroevolution is on a scale of separate gene pools where as Microevolution is about one gene pool. Macroevolution doesn’t always happen all at once. It could also be gradual changes over a long period of time which is known as gradualism. However there is another theory known as punctuated equilibria. Punctuated equilibria is a way to explain long phases of stability that then change drastically. It’s kind of the change you can see over time when looking throughout history. Changes in biodiversity could be an example of macroevolution along with fossils and many other things. Macro and Microevolution are major parts of evolution.
Biochemistry can be used as even more evidence for evolution. Biochemistry is used to reveal similarities of organisms in different species. For example the metabolism of different organisms have the same basic biochemical compounds. Cytochrome C is an example of a compound found in all organisms. There are also certain proteins found in almost all organisms that prove common ancestry, because those compounds are so complex that is extremely unlikely that they developed on there own but still somehow identically. With biochemistry you can also tell that there are differences in the amino acid sequence. Knowing that you can tell which organisms are more closely related than others. And knowing that organisms are so closely related brings us to embryology. All vertebrate organisms have similar embryos but as the embryos grow, the differences in them start to become more noticeable. Studying the development of the embryos help scientists to understand evolution more. Ernst Von Baer claimed that “the more closely related any two species are, the more similar their development” even before Darwin proposed the theory of Natural Selection. And since all organisms share common ancestry, their embryos are similar. Just like an organisms embryo, a fossil can also be used to show evolution. Fossils are generally found buried in a certain order. The order an organism is, the further down it would be buried. For example fish would be underneath amphibian, which would be underneath reptile, and so on. The further down something is buried, the older it is. Because of this, you can use the fossils to witness the change in an organism over a long period of time. Transition fossils are also used because they show the transition from one organism to another. It lets you witness the changes of one species to another. Johann Wolfgang von Goethe developed the idea of comparative morphology. Comparative morphology is the study of similarities and differences in organisms to see similarities in them. This helps scientists to notice how similar different species actually are and how they might have evolved from other species.
After learning about these scientists and all of their beliefs, it’s lead me to believe that evolution definitely exists. Fossil evidence was one of the most convincing for me, along with the theory of natural selection. When I learned about them, it opened my mind up, and I started to consider possibilities that I never really believed before. The theories of Charles Darwin are what mainly convinced me that evolution exists and takes place over a long period of time. I’d have to say that I am definitely a believer in evolution now.
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