Welcome to our blog about evolution. Throughout our blog you will be able to find great supporting facts to evolution and why the theory of evolution still stands strong. We have blogs about evidence, facts, and famous scientific discoveries. Thanks for visiting out site.
Jessica, Jack, and Liang
Richard Owen (1848) introduced the term homology to refer to structural similarities among organisms. Homology involves the theory that macroevolutionary relationships can be proven by the similarity in the anatomy and physiology of different animals. Darwin then made sense of homologous structures by relating it to an evolutionary explanation for them. Darwin said, a structure is similar among related organisms because those organisms have all descended from a common ancestor that had an equivalent trait. Darwin’s evolutionary homology theory has made homology a well known proof of evolution. Claims have been made by many scientists (ex. Conklin) that the only natural explanation to homology is, in fact, evolution. Scientist Conklin gives and example by saying that the resemblance between emryos, larvae and adults
‘are just as genuine homologies as those between adult structures, and the only natural explanation that has ever been found for such homologies is inheritance from common ancestors … . These fundamental resemblances, or homologies, as they are technically called, call for some explanation, and the only natural explanation that has ever been proposed is evolution.’
Bergman, Jerry. “Does homology provide evidence of evolutionary naturalism?”.ANSWERS. 10/29/09<http://www.answersingenesis.org/tj/v15/i1/hom ology.asp>.
There are many evidence that support evolution for example, the world is not the same as it was 5 billion years ago. In fact, earth didn’t have any life on earth until 1.4 billion years later. That was when liquid water was found on Earth and that began the start of bacterias and other organisms on earth;scientists have found bacteria that have been around for 800 million years ago. Fossil evidence prove that dinosaurs were around approximately 300 million years ago but the fact that there aren’t any dinosaurs roaming around proves Darwin’s concept of natural selection and survival of the fittest. The living forms in the modern times are different than the living forms from billions and billions of years ago. For example, tigers and lions arose from their common ancestor Smilodom also known as the now extinct Saber-Tooth Tiger. Instead of the Smilodom roaming around the wild, there are tigers and lions, the offspring of years and years of evolution.
Moran, Laurence. “Evolution is a Fact and Theory.” The Talk Orgins Archives. 22011993. Talk Orgins, Web. 29 Oct 2009. <http://www.talkorigins.org/faqs/evolution-fact.html>.
Darwin’s theory of evolution revolves around four main points. The first one is that the present organisms,although resembling their ancestors, are not the same. Their DNA and physical features are different from their ancient ancestors. This proves that the world is not the same as it was billions and billions of years ago; it’s constantly changing. Darwin states that fossils are proof that organisms are constantly changing with the world. This brings up the second point, the branching of organisms. Certain organisms possess the same physical features because they share common ancestors but on the other hand, organisms who live in the same geographical area also possess similar features because of the environment. The third point is that evolution is a slow and tedious process that takes time;fossil records support the fact that evolution is gradual. The fourth point that Darwin makes is natural selection. This states that organisms with an advantageous trait survive and continue to have offspring.
“Darwin’s Theory.” Evolution and Natural Selection. 07052009. University of Michigan, Web. 29 Oct 2009. <http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html>.
The first stages of life are commonly overlooked when focusing on evolution. When people think about evolution, famous text such as “The Origin of Species” often come to mind. This information allows answers about where different organisms of species come from and how they derived from separate species. However we don’t commonly look at where life started and where evolution began. There are four proposed stages for how life started on earth. Stage one, nucleotides and amino acids were produced prior to the existence of cells. Stage two, nucleotides and amino acids became polymerized to form DNA, RNA and proteins. Stage three, Polymers became enclosed in membranes, and stage four, Polymers enclosed in membranes evolved cellular properties. Of the four stages stage one has lead to the most questions, questions like, how did nucleotides and amino acids form on primitive earth?
Before molecular organisms existed the world was composed of inorganic elements. Elements such as H2O, H2, CH4, and NH3 were thought to be abundant on primitive earth around the 1950’s. Stanly Miller famous for “The Miller and Urey experiment” was able to create large molecules from the above elements, molecules such as amino acids, and nitrogenous bases both of which are found in nucleic acids. However Miller’s hypothesis soon found a lot of criticism. Modern scientist now believes that primitive earth was not a reducing atmosphere but instead was a neutral environment, made of mainly CO, CO2, N2, and H2O
Another hypothesis made was the “extraterrestrial hypothesis” which stated sufficient organic carbon was present in asteroids and comets. These missiles contained orgain carbon, including amino acids and nucleic acid bases.
A third most popular hypothesis made was “The deep sea vent hypothesis” Chemist Gunter Wachtershauser proposed that key organic molecules may have derived from deep sea vents, the vents release gaseous substances from the interior of the earth at high temperatures. He proposed Molecules may have formed in the temperature mixture between the extremely hot vent water and the cold sea water that surrounds the vent at the bottom of the ocean.
To lead to evolution we first must have something that will evolve. These three hypothesis support ideas that have began the road to evolution.
Robert, Brooker. Biology. 1st. New York, New York: McGraw-Hill, 2008. Print
Fossil’s have provided strong detailed evidence toward the support of evolution. It shows a good example of natural selection through time. The horse fossils are a common example of fossils supporting evolution. The earliest of these fossils showed that the animals were small with short legs and wide feet. These early horses lived in wooded habitats and would have eaten leaves and herbs. From these early examples of the horse family to horses today, there had been a lot of adaptive changes, including size, foot anatomy, and tooth morphology. The first horses were around a dogs size. While modern horses can weigh more than half a ton. Starting with Hyracotherium (earliest horse relative) there has been major changes. Though these changes did not take place immediately there was about fifty-five million years in which these changes happened. Fossil records show small changes as the horse forgoes evolution through time. Each change leading you closer to modern day horses.
http://darwiniana.org/horses.htm
In the 19th century, a man called Charles Darwin, a biologist from England, set off to investigate species on an island now known as the Galapagos Islands. While there, Darwin came up with the belief that over time species must adapt to suit their environment. If the trait was not beneficial then it would die off. If the adaptations were beneficial to the species, then that trait would be passed on to the future generations, in turn making that species better than before. Darwin discovered that species were constantly either changing or evolving. Darwin called this idea natural selection, or survival of the fittest. From there he discovered that the traits slowly became more and more distinct and eventually resulting in an entirely new species.
An example of natural selection is Darwin’s Finches. While on the Island of Galapagos, Darwin collected a number of small birds not knowing their significance. After returning home Darwin examined the birds and made an astounding discovery that the birds, while all different, were still closely related. He discovered that all the birds were indeed finches and more interesting they had all originated from one single finch species, this meant that at least 13 species of finch evolved from one single ancestor.
Paul, Sarah. “GENESIS the beginnings”. Think Quest. 10/27/09. <http://library.thinkquest.org/18757/darwinstheory.htm>.
