Evolution is a theory that is supported and proved with proper evidence. There are many facts learned through the dissection and study of frogs and rats as well as research that proves that evolution is real. The definition of evolution is an adapt or change in an organism's DNA because of the environment to help the organism survive. The environment plays a huge role in evolution as will be mentioned later in the article. The beginning of life that basically started the evolution process is very important to know in order to show that evolution exists. Life first began with early molecules which the Miller-Urey experiment proved. This experiment was conducted by Stanley Miller and Harold Urey in 1953 at the University of Chicago. Their experiment proved that molecules can be made from chaos and that that is how the first molecules were made. It started with different gases in the earth's atmosphere combining with heat and sparks, which is energy, to make the first amino acids through the chemical reactions and chaos.
Evidence of Evolution
If recalled back to a previous unit, survival and reproduction is the goal of life. In order for organisms to survive, they need to adapt to the environment and change their characteristics or genes in order for them to keep living or else they will die. If this characteristic that has been changed is effective and needed for survival, then when the organism reproduces, that characteristic which is needed for the well being of an organism will be passed on to the offspring through their genes and DNA. This is what leads to the survival of the species. This is also called genetic variation. Genetic variation is basically when there are differences between individuals or to differences between populations. Mutation is the ultimate source of genetic variation, but mechanisms such as sexual reproduction and genetic drift contribute to it as well. Genetic variation helps the species survive through adaptations with the environment. This supports evolution because evolution is the adaptation made by an organism's DNA due to its environment in order to help the organism survive. An example of a change in DNA made by an organism that slowly changed its descendants are the horses. It can be said that a specific part of an organism's body has evolved when something modern is compared with something ancient and the two parts have the same function but are different in form. Evolution can also be found when something disappears over time because it becomes unnecessary so the organism stops using it. The ancestors of the modern-day horse used to have toes as well as a smaller skull but now the horses have no toes. Over time, the terrain of the land where horses lived in changes and it became more rocky and it hurt the horses feet so they needed some sort of protection for their feet which is why modern-day horses now have no toes, but hooves instead. The hooves also help the horses run faster so that they can run away from predators faster, and as time went on the middle toe of the ancestor horse grew larger and the other toes smaller and eventually useless and the middle toe became the hoof. Although the functional toes of the horse have disappeared, the remains of tiny vestigial toes can still be found on the bones above their hoofs. This clearly shows that the horses went through evolution because they needed to survive and so they had make adaptations and change their body and DNA.
Another piece of evidence that shows that evolution is real comes from a rat and frog dissection analysis. First of all, from what is known about the survival of organisms, every living organism NEEDS water, air, sun, and food in order to survive. Obviously the sun was the first to form or else without it, no living organism can be formed, but with the sun, water is also needed. Because of photosynthesis, it is known that every plant needs water in order to form glucose so that other living organisms can eat it and make energy so that they can survive. All living organisms also need water in order to digest the food (metabolism) to make energy and without it, no organism would be able to survive. Since water is so important, the earth was first all water and then it slowly had land appear. With water surrounding the entire earth, the first organisms had to be water animals such as fish. Now with fish being the first organisms, as the water decreased and land started to appear, there had to be an adaption with the organisms so that they could also go on land. This formed the frogs which can breathe underwater and swim but they can also survive on land because of changes DNA had to make in the fish. It can be proved that the fish evolved into frogs because of tadpoles which look and act like fish even though they are classified as amphibians. Tadpoles are just baby frogs that are able to breathe underwater with their gills, but as they grow they develop lungs meaning they can breathe on land as well as water making them amphibians. This is evidence of evolution. Furthermore with a more detailed explanation is the evolution from frogs to an only land animal specifically rats. To prove that this is evolution, a dissection of a frog and rat was done to study these two organisms in more detail. Some physical homologous structures, meaning consistent traits that show common descent, when comparing the frog and rat were that they both have skin, hands, feet, two arms, two legs, etc. This means that these traits have a similar structure, but a different function for each structure. For example, the function of skin in a rat is to keep everything out and everything inside in, while in frog, the skin allows water to come in through its pores. The frog's webbed feet are so that they can swim, while the rats toed feet are so that they can climb. The frog has longer arms and legs than the rat because it needs them to jump and swim while the rat is not built for swimming so it does not need those arms and legs. The frog and rat both also have some analogous structures. Analogous structures are different structures but they have similar functions. An example of that is how a rat is warm blooded and keeps warm by using its fat, while the frog is cold blooded so when it is cold it goes into the sun and warms up. Both of these allow them to keep their body temperature at the right degree for them to survive. Another example is that the frog has strong muscles in its core,abs,and hamstrings.This is because the frog needs these muscles to hop which is how it moves. So if its muscles were weak they would not be able get away from their predators. The rat has stronger back muscles than the frog because back muscles are needed in order to pull up or climb and so the rat needs it as do most land animals since they climb unlike frogs. There is also a vestigial structure that was found during the observations of the physical structures which is very obvious. Vestigial structures are structures that are present in either the old or new organism but absent in the other. This structure is that the rat has a tail while the frog doesn't. Although vestigial structures are usually when the old organism had it but the new doesn't, in this case it is the other way around. The reason the rat got a tail that is hairless is because it is a heat loss organ that helps the rat release excess body heat when they are hot. These all prove that evolution exists because whether the structure is the same, the function is the same, or if the structure appeared suddenly, they all happened so that they could survive which goes back to the definition of DNA. In all situations the DNA had to change because of the environment so that they could survive.
When we look deeper into endosymbiosis, it shows how simple cells become complex cells by taking amino acids inside and becoming complex that way. This shows evolution because the simple cells are turning into complex cells by adding something and adapting to that being inside of it. This changes the DNA because amino acids are the building blocks of all biological processes since they make up the protein needed to carry out many important bodily functions, such as giving cells their structure. This means that the structure of the cell will change meaning the DNA has to change which once more agrees with the definition of evolution. Researcher that say that evolution is not real and that it is just a fantasy often argue about the theory of Darwinian evolution which is the idea that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce. They argue about how if this theory was true then how come humans are not immune to diseases like the flu and that shouldn't the genes of the humans that are immune to the flu get passed down and become dominant traits. This questions that they have are understandable but these scientists are missing the concept of how natural selection is the survival of the traits that are beneficial to survival AND that these traits have to be reproducible. Not everything is reproducible, although the strength of the immune system can be passed down to the offsprings, it doesn't always. There are other things that come into play when talking about a person's immune system. Also, the flu might not be being passed down to become dominant traits yet, but in the future it might. The reason is that researchers say that the immune system has evolved to reject some pathogens and even some cancers so that means that in the future, immunity to the flu could also be passed down. Researcher also give another reason why a strong immune system being passed down is not always helpful since high levels of immune function can also make the body more harmed by autoimmune diseases, occurring when the body uses its own immune system against itself by attacking healthy cells. This proves that evolution does exist but it just takes some time to be able to see the difference.
In conclusion, evolution does exist even though some might think otherwise. It does take some time for evolution to be clearly seen happening but there is solid evidence of it being true and as time goes on, more and more things will happen that will help to prove that evolution exists. The pieces of evidence right now that prove that evolution exists are real life examples that compare horses from ancient times to now, examples that show how animals today have evolved from each other based off of what animal was created first due to the necessities of life, how endosymbiosis supports evolution, and how the passing on of the immune system is possible with consequences but is also evolution. In general, all of these support the definition of evolution proving that evolution does exist.