Why is evolutions primary mechanism mutation ?

It doesn't have to be a "positive mutation", and if the mutation is in the zygote, then it will end up in all the cells in the whole organism.I can see what you mean about the animals mutating things that they seem to already know how to use. Usually, however, the mutations are so small that animals don't need to learn anything new, and if they did, they would have dealt with their mutation since their birth so they would be used to it. As an example, look at dogs. There are all sorts of dogs, with huge variation in size and shape, so much so that if I had to compare, say, the skulls from a greyhound, a chihuahua, and a bulldog, I might think they belong to different species. All this variation is caused by mutations, and then people selected for traits that they liked. Despite all this variation, dogs don't have any anatomy that they don't know how to deal with.Here is another example of a mutation. These cats are members of the Scottish fold breed. Their ears are folded backwards due to a mutation in just one gene, and people think its cute so they bred lots of them. The mutation probably occured sometime around 1961, because that is the year in which the first cat with folded ears was discovered. This change isn't an incredibly large change, just enough to be noticeable, but it doesn't affect the cat in such a dramatic way that it prevents them from reproducing.

I'm not trying to be mean but it might be a really good idea to actually read some biology text books if you want to be able to discuss these concept intelligently.At the moment it sounds like you haven't got the first clue about either molecular biology, genetics or how evolution is supposed to operate. It is all very well for people to address individual misconceptions and mistakes but unless you have some fundamental grasp of the concepts involved this sort of discussion can't really go anywhere.Of course if you did have that sort of fundamental grasp you wouldn't have to ask such ridiculous creationist strawman based questions anyway.Perhaps rather than re-reading about scientific creationism you should use some of the books available at NCBI in order to find out something about the subjects of genetics and molecular biology.TTFN,WK

If you want to learn more about evolution, I recently read The Blind Watchmaker, by Richard Dawkins. It is fairly long, but very interesting, and much easier reading than many textbooks. Dawkins has amazing talent in writing and does an excellent job of explaining how natural selection works, arguing that the Darwinian version of evolution is the only theory that can acceptably explain life on Earth. The Blind Watchmaker was a national bestseller. He has written other books as well, but I haven't read any of them yet. You should look into reading something by him.

These questions arose from reading biological textbooks. Keep in mind that the school system does not give a satisfactory explanation of evolution. We are told that natural selection decides what must mutate and it is successful. I am asking why it chooses this random factor as its mechanism.

Well, if so, you're being told wrong stuff.There is no plan to evolution, no goal or direction.Mutations happen all the time and in every single organism.Natural selection is simply a description for the environment, where we and every other thing lives.

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Aslan is not a Tame Lion

If it is a description of the enviorment, then why aren't all animals the same? If natural selection decides this depending on the enviorment then why do some animals hibernate and migrate?

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If life wasn't meant to be lived then why is there death?

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.

Because we don't all experience the same environment. In addition, since mutations are random, there can be many that are still successful.This message has been edited by jar, 09-14-2005 03:23 PM

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Aslan is not a Tame Lion

But mutations can only occur so often. You are lucky to get one good mutation every say 1 billion years. When it moves in a positive direction you have evolution. When it moves in a negative direction you have entropy. You speak of copying DNA but that is embryology.

Not at all. Mutation happen all the time. You yourself probably have twenty or thirty or more mutations.This message has been edited by jar, 09-14-2005 03:31 PM

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Aslan is not a Tame Lion

You are referring to inheritance. That makes very little sense.

No, I'm saying that mutations are actually not very unusual. They happen all the time.

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Aslan is not a Tame Lion

I they happen all the time they would still happen today. Seeing as how scientists have said evolution can not be observed, I fail t see how that is possible.

But mutations are seen today.There are several that are sweeping through the human population right now. There is one that seems to provide all the benefits in malaria resistence of sickle cell but without the draw backs.Kinda exciting.

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Aslan is not a Tame Lion

Yeah, I remember in high school, my biology teacher practically called me a creationist when I told her she was wrong and that modern humans didn't evolve from Neanderthals. They gave me a really cursory description of natural selection, and didn't spend much time on it at all. I realize that there is a limited amount of time in the school year, but I think that we should have spent more time on evolution and less on stuff that we will forget right after the test, like memorizing all the enzymes and chemicals in photosynthesis. I guess the teachers aren't allowed to make their own curricula though. Florida isn't famous for its stellar school system either.But getting back on topic, I think the reason your teacher said that is because the environment tends to "choose" certain individuals as more fit than others, where fitness is determined by the number of viable offspring the organism produces. She might have misunderstood something about natural selection. Mutations occur more or less randomly. They occur all the time. It isn't a rare thing at all. They are simply products of an imperfect copying system. All the errors lead to variation within a population. As time goes on, some individuals end up with the ability to produce more viable offspring than others. These individuals are said to be more "fit". They pass on their mutations and eventually the whole population is full of these "fit" genes.You mentioned in another post that this sounds like it would make animals all the same. There are a few factors that prevent this, but the most important one is the environment. The environment is always changing, so what may work today might not work tommorow. If an area is invaded by a new plant species that outcompetes some native plant, the way kudzu outcompetes practically everything, animals dependent on the native plant may have to adapt to eating the new plant. Any that can't eat it will just starve to death or get sick and die from that or get eaten by something that likes to eat sick herbivores.Imagine a petri dish with millions of bacteria living in it. If you add an antibiotic, the bacteria will die. However, if only one out of those millions of bacteria has a mutation that lets it survive with the antibiotic, then it will start its own colony and all its offspring will probably also be resistant to the antibiotic. You could also add only a small amount of the antibiotic. Maybe some bacteria can deal with a little bit, but others can't. Then you could keep breeding bacteria that are stronger and stronger, until the antibiotic is useless for killing bacteria. But if you picked out a new antibiotic it might kill them all off.This is a simple example of a changing environment. You started out with bacteria that aren't resistant, and you end up with resistant bacteria. So selection didn't determine what has to mutate, it just picked out a particular individual who got lucky and had mutated.