Discussions:Evolution
Evolution versus Creationism:
A Topic in Debate
Introduction Page
Evolution and Creation debates have been going on for ages. Now the Internet is full of sites promoting each side. So what makes this site different? I am going to try to present both sides of the argument in as fair a \ manner as possible. Both sides must "prove" that theirs is the better claim. If neither does than there will be no winners. The claim that on side automatically wins because the other cannot prove its case is unfortunately the way science works, but not necessarily intelligent. This is why we thought the world was flat for so many years, even though the "proof" was lacking. I believe that any person arguing a case should admit their possible biases and beliefs up front. I am a Christian and believe that creationism does present an intelligent argument or our origins. This means that unless I check my thoughts and think critically I tend to understand and believe Creationism claims more easily than I do that of Evolution. However, in this case I will try to present both sides equally and not let my bias affect the evidence. I also believe that they should present any qualifications that they have. In this I have to admit that I'm no scientist; I've taken College Biology as well as High School Biology (which was taken from a private Christian School, giving it a Christian perspective). One of the smartest people I know though was my Astronomy professor. He was a doctor - in psychology. Did this mean that he wasn't qualified to teach College Astronomy? No, because his hobby was astronomy. He knew as much about the stars and astronomy science as any regular teacher. My hobby is reading and thinking about Creationism and evolution. I read books about both sides, own many college biology books and watch any show that talks about evolution. I also search the Internet for arguments and read their pages. In short, I feel that while I'm not an expert, I do know enough to speak about evolution.
Evolution - What is it exactly?
In order to accurately discuss a subject, the major terms need to be defined. To be complete many definitions should be examined and analyzed. Through these a proper definition can be reached. Evolution is defined in many different ways. Webster's Universal College Dictionary defines evolution as:
n. 1. Any process of formation or growth; development: the evolution of the drama. 2. A product of development; something evolved. 3. biol. a. change in the gene pool of a population from generation to generation by such processes as mutation and natural selection. b. the development of a species or other group of organisms; phylogeny. c. the theory that all existing organisms developed from earlier forms by natural selection; Darwinism. 4. A process of gradual, peaceful, progressive change and development, as in the social or economic structure. 5. A motion incomplete in itself, but combining with coordinated motions to produce a single action, as in a machine. 6. A pattern formed by or as if by a series of movements: the evolutions of a figure skater. 7. Math. The extraction of a root from a quantity. 8. A military training exercise. 9. A movement executed by troops in formation.
Looking at another dictionary reveals mostly the same definitions with some slight differences. According to Reader Digest's Illustrated Encyclopedic Dictionary evolution is:
n. 1. A gradual process in which something changes into a significantly different and usually more complex or more sophisticated form. 2. Biology. a. The theory that groups of organisms may change with the passage of time so that new species differing morphologically and physiologically from their ancestors are formed. See natural selection. b. The historical development of a related group of organisms; phylogeny. 3. The gradual process of development or growth of something, as of a social institution, geographic division, or system of thought. 4. often evolutions. A turning movement that is part of a larger pattern, as: a. A wheeling motion in a dance. b. a tactical or parade-ground maneuver. 5. A yielding of throwing off of gas, vapor, or heat. 6. Mathematics. The extraction of a root of a quantity. In this sense, compare Involution. [Latin: volti, an opening an unrolling, from voltus, past participle of volvere, to roll out, to open, EVOLVE] See feature, next page.
While most of these definitions are vague or not related to science, the Biology and Darwinism definitions from each are both useful. But do they convey enough information about evolution for discussion? Are they considered accurate by evolutionists? Which definition is more accurate? Looking at some Biology books would be beneficial.
Evolution According to Science Textbooks
In both the first and second editions of Biological Science by William T. Keeton, interestingly enough, there is no formal definition of evolution. Instead, the text indicates what postulates form the theory of evolution as put forth by Charles Darwin. Both editions are the same in stating:
The theory of evolution, as modified in the years since Darwin, will be treated at some length in Chapter 17. But since we shall have to refer to this all-important unifying principle of biology in interpreting much of the material covered in earlier chapters, let us briefly examine the central concepts of Darwin's theory here.
The theory consists of two major parts: the concept of evolutionary change and the concept pf natural selection. First, Darwin rejected the notion of living creatures that are immutable products of sudden creation, that they exist now as in precisely the form in which they have always existed. He insisted that, on the contrary, change is the rule, that organisms living today have descended by gradual changes from ancient ancestors quite unlike themselves. Second, Darwin said that it is natural selection that determines the course of change, and that this guiding factor can be understood in completely mechanistic terms, without reference to conscious purpose or design. (pg. 7)
The text then goes on to examine in more depth the two parts of Darwin's Theory. The text explains that during his time each species of animal was thought to be a separate act of Creation by God and were immutable. In addition, as stated by evolutionists, because of growing evidence in the fossil record, creationism at the time was suggesting that there had been multiple catastrophes and each time God recreated new animals. Most importantly, the text describes what kind of evidence Darwin required to prove his theory (this same evidence will be necessary for this test):
First, he could point to the fossils. During the latter part of the eighteenth and the first half of the nineteenth century, geologists had unearthed many fossils and realized that most of them represented species no longer living on the earth and, conversely, that few living species were represented in the fossil record. In other words, forms of life different from those known today inhabited the earth in past ages. . . To us the existence of fossils seems convincing evidence that the history of life on earth has been marked by change. But when it was first suggested that the extinct creatures whose remains are preserved in the rocks as fossils represented the ancestors from which the organisms living today are descended, it was urged instead that these extinct species indicated the occurrence of catastrophic extinctions at various times in the history of the earth, followed by new episodes of divine creation. According to this hypothesis, each species would have remained unchanged from the time of its creation until the time of its extinction; there would have been no evolution.
Soon, however, the fossil record itself made this hypothesis untenable. As more and more fossils were discovered and studied, it became evident that gradual shifts in characters (physical traits) could be traced through time. If an investigator studied the fossils in one rock layer and studied the fossils in a slightly more recent layer, he would often find that those in the more recent layer, though very similar to the older ones, showed slight differences. If then he examined a third layer slightly more recent than the second, he would again find that slight changes in the characters of the fossil species could be detected. In this way, by studying a series of successive rock layers, he could reconstruct the sequence of changes through which a given lineage had passed. He could even predict what the fossils in some intermediate layer not yet studied would be like and then test his hypothesis by locating and studying such a layer …
Second, Darwin could point to resemblances between living species. If one looks at the forelimbs of a variety of different mammals, for example, one will find essentially the same bones arranged in the same order. The basic bone structure of a man's arm, a dog's front leg, or a seal's flipper is the same; the same bones even are present in a bird's wing. True, the size and shape of the individual bones vary from species to species and some bones may be missing entirely, but the basic construction is unmistakably the same. To Darwin, the resemblance suggested that all these species had descended from a common ancestor from which each had inherited, with distinctive modifications, its forelimb. The fact that some species posses in reduced and nonfunctional form structures that in other species have important functions further convinced Darwin of the validity of his theory. Why would a Creator given pigs, which walk on only two toes per foot, two other toes that dangle uselessly above the ground? Why would he have given human embryos gill pouches and well-developed tails only to make them disappear before the time of their birth? It seemed much simpler to assume that that such structures were inherited vestiges of structures that functioned in ancestral forms and that still function in other species descended from the same ancestor.
Third, and particularly convincing, Darwin could point to changes produced in domesticated plant and animals.
The text then proceeds to present the concept of natural selection as Darwin stated it. In fact, this contribution of natural selection is what allowed evolution to finally have a solid argument - natural selection offered the mechanism by which animals and plant change. As the text states:
His [Darwin's] first clue came from the breeding of domesticated plants and animals. When pigeon breeders, for example, are developing a new strain, they exploit the variation always seen among individuals by selecting the ones best endowed with the characteristics they want to propagate and using them as the parents for the next generation. The same procedure is followed in each successive generation; those individuals that most nearly approximate the desired type are selected as breeders, and individuals that deviate markedly from the desired type are are eliminated. After many generations of such selection, the pigeons will be very different from the ones with which the breeders began. Essentially the same procedure is used in developing a new breed of dog or horse or wheat or chrysanthemum. Since individual variation occurs in all populations of wild organism, just as it does in populations of domesticated ones, Darwin reasoned that evolutionary change in those populations must be caused by some sort of natural selection for individuals with certain characteristics and elimination of individuals with other characteristics. But what sort of selective force might be at work in nature? The answer eluded Darwin for several years.
Then in 1838 he read a book entitled An Essay on the Principle of Population, written by Thomas R. Malthus (1766-1834) in 1798. This book suggested to him how he could account for the selection he felt sure must be operating in nature. Consider for a moment a population of gray squirrels. If this population is to be perpetuated at a stable level, each pair of squirrels must leave enough offspring to replace itself- two, if we assume that all the offspring survive to reproduce. If the average number of progeny per pair were more than two then the population density would rise; if the average number were less than two, then the population density would fall. Now, even a casual study of actual populations will reveal that the average number is always more, usually far more. A single female frog may lay many thousands of eggs each years; a single pair of robins usually has two clutches per year of four to five eggs each; and a pair of gray squirrels usually has two litters per year containing two to four young each. A single oak tree may produce millions of seeds during its lifetime. Very large reproductive potentials are, in short, the rule in all types of organisms. Yet natural populations usually remain relatively stable over long stretches of time; they may fluctuate noticeably, but they never even approach the level that would be expected if all their progeny survived to reproduce. It is obvious, therefore, that a very large percentage of the young of any species fail to survive and reproduce.
Once Darwin recognized that in nature the majority of the offspring of any species die before they reproduce, he had the clue he needed to explain natural selection. If survival of the young organisms were totally random, if each individual in a large population had exactly the same chance of surviving and reproducing as every other individual, then there would probably be no significant evolutionary change in the population. But survival and reproduction are never totally random. Some individuals are born with such gross defects that they stand almost no chance of surviving to reproduce. And even among individuals not so severely afflicted, differences in the ability to escape predators or obtain nutrients or withstand the rigors of climate or find a mate, etc. ensure that survival will not be totally random. The individuals with characteristics that weaken their capacity to escape predators or obtain nutrients or withstand the rigors of the climate, etc. will have a poorer chance of surviving and reproducing than individuals with characteristics enhancing their capacities. In each generation, therefore, a slightly higher percentage of the well-adapted individuals will leave progeny. If the characteristics are inherited, those favorable to survival will slowly become more common as the generations pass and those unfavorable to it will become less common. Given enough time, these slow shifts can produce major evolutionary change.
Now let us compare the propagation of favorable characteristics in nature, as outlined above, with their propagation in domesticated organisms. In each case far more offspring are born than will survive and reproduce; i.e. in each case there is differential reproduction, or selection. in the breeding of domesticated plants and animals, the selection (differential reproduction) results from the deliberate choice of the breeder. In nature the selection (differential reproduction) results simply from the fact that individuals with different inherited characteristics have unequal chances of surviving and reproducing. Both sorts of selection, artificial and natural, cause some inherited characteristics to become more prominent in the population and others to become less so as the generations pass. Notice that individuals, once born, are not changed by selection. An individual cannot evolve. The change is in the makeup of the population.
One difference between evolutionary change in nature and the change produced by breeders should be noted. That is the rate of the change. Breeders can practice rigorous selection, eliminating all undesirable individuals in every generation and allowing only a few of the most desirable to reproduce. They can thus bring about very rapid change, as we all know. Natural selection is much less rigorous. Some poorly adapted individuals manage to survive and reproduce, and some well-adapted individuals are eliminated. Hence evolutionary change is usually rather slow; major changes may take thousands or even millions of years. Fortunately for Darwin and his theory, the geologists of his day, particularly Charles Lyell (1797-1875), one of the greatest geologists of all time and a close friend of his, had provided evidence that the earth could not possibly have been created in 4004 B.C., as many churchmen insisted, but that it must be hundreds of thousands times older. Without the geologists' gift of immense spans of time, Darwin's theory of natural selection could not adequately have explained evolutionary change.
In Summary, we see that Darwin's explanation of evolutionary change depend in terms of natural selection depends on five basic assumptions:
- Many more individuals are born in each generation than will survive and reproduce.
- There is variation among individuals; they are not identical in all their characteristics.
- Individuals with certain characteristics have a better chance of surviving and reproducing than individuals with other characteristics.
- At least some of the characteristics resulting in differential reproduction are inheritable.
- Enormous spans of time are available for slow, gradual change.
All the known evidence supports the validity of these five assumptions.
Work still in progess …
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