Why is evolutions primary mechanism mutation ?

Hello, igor.Unfortunately, it sounds like what you are being taught is totally wrong. Probably not your fault; either the text book is mistake or, more likely, the teacher's explanation of the text book is misleading.Mutations just happen. Whenever a cell divides, its DNA must be duplicated so that each new cell gets a copy. But no process is perfect; there will eventually be a mistake in the copying process -- this is what a mutation is. Mutations, copying mistakes, are simply a part of this imperfect world.If the mistake occurs in a cell that is a germ cell (say a sperm or ovum), then the entire new organism will have identical DNA with this mistake.Now this mistake may have no effect on the organism. Or it may have an effect. This effect may be bad for the organism; it might make it harder for the individual to survive, mate, and leave behind offspring (which would also have this same DNA); this organism is therefore more likely to die before breeding.On the other hand, the effect may be a positive one; it might make legs just a tad longer, for running faster, for example; it might make the spines in the fish's fins just a little stiffer so it can use them to crawl through the vegetation on the pond bottom; it might make the brain just a little larger, leader to greater intelligence. In this case, the individual will be more likely to survive and breed, and its offspring will have this same DNA.Now, over several generations, the individuals with the "good" DNA will produce a few more offspring, on average, than the individuals with the "old" DNA. Therefore, the proportion of individuals with the "good" DNA will increase, the individuals with the "old" DNA with decrease in number, and eventually, the last individual with the "old" DNA will die, and the species will have evolved just a little.Notice that natural selection is not doing anything. It is simply a word that describes the process, where genes that cause problems will cause its host to die without breeding, while genes that cause improvements will be more likely to survive and leave offspring with the same genes.The last part of this post contains a short, capsule description of the theory of evolution.

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I think that we should have spent more time on evolution....

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I recently (about two years ago) read an introductory college biology text; evolution was the central theme of the book. It began with a chapter on evolution, and everthing else in the rest of the book was tied in one way or another with evolution. The theory of evolution is the central, organizing principle of biologyl; nothing in biology makes sense except in light of evolution (Theodosius Dobzhansky).The book was about ten to fifteen years old; I had hoped that it was the beginning of a trend, and all biology texts make evolution the central organizing principle, even high school texts.

There is no single "environment". Every "environment" has many different niches available, where different organisms may use different methods to make a living.

Hi, igor.Here is the entire theory of evolution in a nutshell:1. Fact: Most breeding organisms produce more offspring than is necessary to replace themselves.2. Fact: The population of most species are not increasing.3. Conclusion: Most individuals must die before reproducing.4. Fact: Many of the physical traits of individual organisms are hereditary.5. Fact: Some traits make an organism more likely to survive and reproduce, while others make an organism less likely to survive and reproduce.6. Conclusion: From 3, 4, and 5 we can conclude that organisms with the traits that make them more likely to survive and reproduce will produce offspring with those traits, while organisms with traits that make them less likely to survive and reproduce will leave few or no offspring with those traits.7. Conclusion: A corollary of 6 is that as generations pass, the number of organisms with "good" traits will increase, while the number of organisms with "bad" traits will decrease, until eventually all individuals in the species will have the "good" trait and the "bad" trait will disappear altogether.8. Fact: New heritable traits, usually subtle, occasionally appear.9. Fact: These new traits do not appear in any predictable pattern; these traits can appear in any body part or instinctual behavior; furthermore, some of these traits are helpful to an organism's survival, and others are detrimental.10. Conclusion: From 7, 8 and 9 we can conclude that a species will slowly "improve" with time, as new helpful traits appear and as the organisms with these traits are better able to survive and produce offspring with these traits.11. Fact: There is no mechanism that is known to prevent these small, incremental changes from adding up, over time, to large changes; furthermore, there very few (if any) physical organs and instinctual behaviors in any species that do not appear in simpler versions in other species.12. Conclusion: From 10 and 11 we conclude that there is nothing that will prevent very simple, primitive living species from producing the complex species that we see around us.13. Fact: Occassionally separate populations of a species will become physically isolated from one another and cannot interbreed.14. Conclusion: From 9 and 13 we conclude that these populations will evolve independently; from 12 we conclude that these will become different species.15. Conclusion: From several interations of 14, we conclude that several species can have a common ancestor.Everything that I have labelled as a fact is a fact; these facts have been observed and verified. Everything I have labelled as a conclusion seems to me (and to most people) reasonable conclusions based on these facts. What about all of this do you not think makes sense? More to the point, what here violates any known law?I will end this post with evidence for the plausibility of evolution, and evidence for evolution having actually occurred.16. Fact: Over the course of human history, animal and plant breeders have produce a huge variety of animal and plant breeds; many of these breeds share of common ancestor, and these breeds are often very, very different from one another as well as from the ancestor.17. Conclusion: The appearance of random traits coupled with a selection process can result in evolution.18. Fact: The species can be classified in a hierarchical pattern.19. Conclusion: 15 and 18 allows us to conclude that all known species have evolved from a very few (perhaps one) ancestral species.

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But you guys don't seem to have set the ground rules on "mutation".

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This is a bit of a puzzling request... What is a ground rule?

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ausar_maat has also asked for whatever that means. Ask Yaro -- she seems to understand what he is asking.

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"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt