Darwins Theory Of Evolution By Natural Selection Philosophy Essay
This chapter will focus more on Darwins' Theory of evolution by natural selection, rather that the origins of our universe. This topic of debate is undeniably the most contested when pitting theists with evolutionists. Essentially, the theists have a 'bone' to pick with evolutionists and biologists, whenever they mention the word 'evolution'. Some even laugh when respected scientists suggest that they take a simple trip to their local museum to see at least some fossil evidence of a certain species' progression.
There should actually be no rift between the two. There should be no reason why theists should ignore and deny the evolutionary fact. Indeed, there is a fair number who agree with itâ€¦ they just don't agree with the 'naturally-occuring' idea. It is quite conceivable to me that even the most devout theologian could embrace the fact of evolution and use it as a positive addition to the glory of the god he worships ( whichever one that is ). Why should these two parties not come together and shake hands? Well, maybe it's because science and religion look at the world in different ways. Science is 'all about the evidence' and uses concrete, testable elements; forms hypotheses and has the whole scientific community standing on the precipice, just waiting to prove them wrongâ€¦. That is if they CAN! The more theories are judged, challenged and scrutinized and found to be justified, the more the theory is considered correct. The longer it stays around without being corrected or proven wrong to any degree, the scientific community accepts it as fact. Facts CAN change over time to be sure. With new technologies and equipment, vast improvements in our knowledge increases each year. In this case, evolution IS A SCIENTIFIC concept, and can make no assumptions or opinions relating to a super-natural creator. Conversely, religion is all about faith and the study of ancient, man-made, 'hard-to-get-the-extracted-meaning-out-of' books created 2,000 years ago by an ancient civilization and has nothing to do with evidenceâ€¦â€¦. Was that a jab? Sorry. Only kidding. What I MEANT to say is that religion "invokes super-natural explanations that cannot be tested," and that through that, it sees the world in a different light. As I see it, the two areas do not have to be incompatible, as the religious-minded can agree on evolution without compromising their core beliefs.
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This powerful theory explains much of the way we are, and how we began. Fossils show the preserved history of life. It shows us how we are similar, and different, from other species. It also shows us where certain species were distributed past and present. As I have stated before, many scientific disciplines come together in giving us a vast amount of evidence for this theory. Today, new and exciting DNA and GENOME projects are hard at work showing that we are all connected in some way. I believe these last two items somehow get swept under the rug when antagonists of the theory ask "show me the evidence". Quite learned folks seem to leave out mentioning these new and exciting technologies when asking that question. We will leave that for a bit later.
Mainly they are asking, perhaps quite rightly, where is all this 'mountain' of evidence you have for your evolutionary theory"? OK then. I will attempt to put in concise terms what the evolutionary theory states and a bit of information on the actual physical observation of fossil remains, and how scientists are able to link these together. Perhaps the best introduction to this subject would be a look at the first paragraph of the Paleontological Societies' position statement on Evolution. The paragraph beginsâ€¦. "Evolution is both a scientific fact and a scientific theory. Evolution is a fact in the sense that life has changed through time. In nature today, the characteristics of species are changing, and new species are arising. The fossil record is the primary factual evidence for evolution in times past, and evolution is well documented by further evidence from other scientific disciplines, including comparative anatomy, biogeography, genetics, molecular biology, and studies of viral and bacterial diseases. Evolution is also a theory - an explanation for the observed changes in life through Earth history that has been tested numerous times and repeatedly confirmed. Evolution is an elegant theory that explains the history of life through geologic time; the diversity of living organisms, including their genetic, molecular, and physical similarities and differences; and the geographic distribution of organisms. Evolutionary principles are the foundation of all basic and applied biology and paleontology, from biodiversity studies to studies on the control of emerging diseases." There you goâ€¦â€¦
A little bit of an explanation of exactly what a 'species' is, might be applicable here, as most people are interested in the creation, or progression, of new species throughout the evolutionary time-frame. I do reference this in another part of the book, but here it is again, for clarification. Basically, a species is a group of organisms that can interbreed and create viable offspring. In other words, a species can have babies that can have babies, and so onâ€¦. It has been falsely put forward that a MULE is a new species. No, it is not. When a donkey and a horse mate, one gets a mule. The buck stops there, unfortunatly, as mules are sterile and cannot continue the bloodline. HUMANS, although cosmetically and superficially can be quite varied, are extremely close genetically and can, of course, interbreed making us a uniform species. Why our external characteristics ARE so varied ( skin color, nose-shape, hair formations and color, etc. ) and yet our internal genetics so similar? I don't know if even scientists have an answer for that yet.
Here, in this chapter, and In a previous one, I explained that a theory gets developed and challenged at all stages until it is accepted as fact, and that is the case with evolution. It is not a bunch of scientists getting together in a 'boys club' and having only a few fossil remains and claiming linkage between them. As a theory, evolution "must continue to be open to testing". So far, it has undergone 150 years of such scrutiny and present-day technologies are addressing even "more fruitful inquiries" based on "the tempo and mode of evolution, the various processes involved in evolution, and the driving factors for evolution. Through such inquiry, the unifying theory of evolution will become an even more powerful explanation for the history of life on Earth."
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Before I go on it is worth noting that there is research that is being done in many areas of the fossil record. Apparently there is interest in the concept of how certain species managed to survive past 'mass extinctions' and what type of traits would one have to have over the other to make it through. Was it just luck? Was it a larger geographical 'spread-out' of the related species group that made some of them survive? It is an interesting thought, and one that has added a new dimension to evolutionary theory.
The most common thinking in the 'Natural Selection' process is that it is one that tends to improve the survival characteristics of a certain species, "weeding out organisms with traits not quite suited to a particular environment, favoring those with traits slightly better for promoting survival and reproduction". It is argued, by Dr. David Jablonski, a Paleontologist at the University of Chicago, that most of the traits we see in species today probably are not there for ultimate survival through the very tough times. Most of these "beautiful adaptations will be lost, not because they are poorly adapted to the vast bulk of evolutionary time, but because they happen not to be linked to the kind of factors that promote survival during those short-lived but intense mass extinctions." This, perhaps, can be viewed as obvious but it does promote an interesting area of study that adds to the general understanding and development of present-day evolutionary theory.
Let me digress for a second and say that some theists find the process of evolution too 'random' and 'violent' to be something one would attribute to something God would conjure up. Far from being random ( with the exception of genes and their mutations on individual organisms ) it truly is a 'survival-of-the-fittest' scenario, and very violent, indeed, with each successive generation of species trying to survive the best way they can. One can hardly blame other species for being 'violent', protecting themselves from harm and possible extinction. Look at the great lengths we humans have gone to fight our enemies and to hack away at the environment, all in an effort to prolong our speciesâ€¦.. Violent, indeedâ€¦.. The fact that some theists refuse to accept evolution BECAUSE of it's inherent violent nature is ignoring the very basis of HUMAN nature. We need to survive, no matter what, and are ready to do whatever is necessary to achieve it. Maybe that does not seem like the idea a loving creator would have had when setting out to produce us, but those are the breaks.
To let you all know what is 'generally' accepted by theists and what is perhaps not is explained in this way. You may hear mention of two areas in Evolutionary debates, namely "micro-evolution" and "macro-evolution". The accepted former concept talks about a small-scale change in the genetic 'make-up' BENEATH the main 'species' level. For interest, this comes about by several processes like, mutation, natural selection, and genetic drift. The disputed 'main' part of evolutionary theory ( by THEISTS not scientists ) is the 'macro' concept of the origin of 'higher organisms". Another term for macro-evolution could be called 'descent with modification'- There is much in dispute about what actually constitutes a 'higher organism, but we shall say that it is one of the 'main' species we all recognize today, they having characters in common that make them different from other organismsâ€¦ clear? This macro-evolution includes common ancestry, the relation of all life to one another, and more. Theists have an even larger 'bone' to throw ( sorry ), because evolutionists call this well-scientifically-supported view as a "fact of evolution"- A fact it is, however to theists that may sound too final.
Finding fossils is not easy. Cambrian rock strata, the oldest and most dinosaur and invertebrate-filled type of rock around, has revealed only a relatively small number of animal fossilizations, compared to all types of species that must have lived up to 600 million years ago. The current problem with these fossils is that, ( according to creationists ), there are not enough intermediary fossils showing a gradual change in evolution, as many biologists state as the way evolution works. One of the only alternative theories that evolutionists can come up with is that natural-selection changes happened in large 'spurts', rather that incrementally. There are exceptions to this, as several examples exist that could explain an intermediary in these very old fossils. It is fair to point out that the last 20 years has yielded much more fossil evidence from which scientists can study. I may be repeating myself, but this is a good spot to add that whenever the scientific community comes up with a fossil intermediate between two species, the theists shout that there is now TWO MORE gaps in the fossil record, whereas before there was only oneâ€¦. Sounds like a never-ending storyâ€¦â€¦. It would be impossible to find every fossil for every possible change in the evolutionary progression in a species. The best we can hope for are finds that represent a rather significant change in a species over time, in order to get a better understanding of the ultimate 'direction' of a particular lineage.
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"During Darwin's lifetime, a fossilized species was discovered which appeared to be intermediate between a bird and a reptile. It had feathers like a bird, but a toothed jaw like a reptile. He named it an Archaeopteryx. It seemed to be just the kind of intermediate form which Darwin's theory predicted, and was taken as good evidence for evolution." This helps a lot because recently, fossils of feathered dinosaurs have been discovered that might suggest a link between Archaeopteryx and the theropod dinosaur. The theropod group is very diverse and runs from the large "T-REX" to smaller, flying dinosaurs. One reason why it is difficult to obtain these remains is that they are, indeed rare, and in the case of smaller specimens, their smaller bones wither away, leaving very little ( if any ) trace.
To the uninitiated it might appear that evolutionists seem to be waffling between this theory and that explanation. It is only that the business of evolution is so challenging and includes contributions from paleobiology, geology and organic chemistry ( how living organisms have evolved ) as well as ecology, genetics and molecular biology that attempt to "demonstrate how living species are currently changing in response to their environments and therefore undergoing evolution". Many more 'sub-disciplines' are involved, as well as new concepts relating to the ever-improving technology fields.. Anyone rationally delving into exactly what it takes to prove linkages between fossils in the record will come away awestruck indeed by the massive undertaking it is.
An explanation of NATURAL SELECTION should be placed here for your enjoyment. It is the basic foundation for the study of the most elegant 'family-tree' of all the species, and the main driving force behind Darwin's Theory of evolution. Some dispute over the actual percentage that natural selection HAS over evolution exists ( compared to other factors ), but it is the driving force behind it. Other mechanisms of evolution can also include mutation, migration and 'genetic drift' but we will leave the discussion to the basics. There are three main areas where an individual organism might survive and continue to evolve, thereby having 'natural selection' as the outcome. These three are VARIATION, DIFFERENTIAL REPRODUCTION, AND HEREDITY. Here is a basic example and a description of the three areas as we go:
1) Within certain species you will find there are certain VARIATIONS in some traits. Some variations can occur within a certain species by POLYMORPHISM, in which individuals can exhibit different structures, colors and biochemistry but CLEARLY belong to the same species, as they 'reproduce with one another' ( again, a major element of determining whether two organisms are from the same species â€¦ ).
Another way in which variation can occur is by GEOGRAPHIC variation. Sometimes there is no obvious pattern to these changes, but in CLINAL variation it is interesting to note that this can be a gradual change in some feature, depending on geography. From the Freeman and Herron book (2001) chapter 12, the interesting part is that "in the northern hemisphere you frequently find that populations of mammals are smaller in the south and gradually as you go north you find that within a species the individuals are larger and larger. Such a pattern of gradual change is called a cline so this form of variation is called clinal variation."
The final variation is those within certain HYBRID zones. An example of this would be red-shafted and yellow-shafted flickers ( birds ). On the east coast of the U.S. you get mainly yellow and the west coast the red-shafted flicker. There is a 'convergence-zone' of a few hundred miles where there are a proliferation of both types. SPECIATION is a very complicated area, so these examples will have to sufficeâ€¦.
2) DIFFERENTIAL REPRODUCTION can be likened to the concept of 'survival of the fittest', and is really the ESSENCE of the natural selection process. A very good example of this comes from library.thinkquest.com and it goes like this: "Differential reproduction is the idea that those organisms best adapted to a given environment will be most likely to survive to reproductive age and have offspring of their own. Organisms that are successful in their environments will be more likely to be successful in reproduction, and therefore the better-adapted organisms will reproduce at a greater rate than the less well-adapted organisms". In one example, consider a snow-covered habitat where there are both white and brown-furred small animals that are constantly preyed upon. In this case ( the quote goes on to state ) "the white-furred animals are less likely to be seen by predators and are therefore more likely to survive. Thus, more white-furred animals will make it to reproductive age and have offspring, who will most likely share their genes for white fur. Therefore white fur will come to dominate the population. Differential reproduction, or difference in the rates of reproduction of differently-adapted organisms, will favor the better-adapted organisms at the expense of the worse-adapted ones." This IS getting interesting, don't you think?
3) The third area that natural selection can be observed is the idea of HEREDITY. This is defined as the transmission of character traits from the parents to their offspring. VARIATION also occurs when discussing heredity, as I will state here. From HUBPAGES.com we get this explanation of how heredity works:
"Characters of parents get copied in children. Skin colour, hair colour, height, appearance, etc. In children resemble either of parents or grandparents. This phenomenon is known as heredity.
Chromosomes contain genes, which work like a recording device, recording all the genetic codes of an individual and transferring them to the next generation.
Variation: As half of the chromosomes come from the paternal side and the other half from maternal side, so the offspring will have a mix of characters from both parents. This mixing up of characters creates slight variation in the genetic makeup of the offspring. These variations accumulate over hundreds of years giving rise to an altogether new species."
Lets take a hypothetical beetle as an example, and use the above information as a guideâ€¦â€¦. From evolution.berkeley.edu we can assume that, within the particular species of beetle, that some are brown and some are green. These would be the VARIATION IN CHARACTER TRAITS. "There is also differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis. End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown."â€¦. Elegant, indeedâ€¦â€¦
It is well worth noting that some fairly recent discoveries have shown that sometimes evolution can actually be seen, and I will site some examples of this in a later chapter.
Natural selection is a factâ€¦. just as it is a fact that the earth rotates around the sun ( the last statement proving that science works as time progresses by people challenging these ideas - even if theists put those newly-challenged idea-people in jail for it (( Galileo ). Unlike the theists side, who oft-neglect to answer directly, the reasoned points given by evolutionists in the debate on how we, the human species, arrived here are valid and have been proven time and time again. I will state a few interesting and captivating examples of 'evolution by natural selection' in the following chapter. I found these examples courtesy of NATURE magazine and I will use the next few chapters to let you experience these elegant, amazing links between modern, and ancient animals.
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