Mutation

Well, of course. But the environment changed, and now we no longer need extra teeth to replace the adult teeth we were expected to lose.Mutations are benefical ultimately only in regards to environment.

Muhd,
1) First and foremost one must get past the idea that mutation means "bad, detrimental, suboptimal, etc". I think it would really be better to discuss changes and whether or not those changes resulted, as a whole, in a species persisting to present day existence.
2) Many people that post in the same vein as you try to play a game whereby you decide what is a beneficial change and what is not. A case in point is that you have been informed of Sickle Cell Anemia. Now you might make the initial judgement that this is/has been a detrimental change in DNA in a Western European environment, BUT in fact this is a change that confers survivability in the environment that the organism lives in.So, in answer to your challenge. Cut back on the "cheesy", B-rated, sci-fi movies (even though I like a few of these myself) Mutation=Change and that is it. EVERY SINGLE SPECIES you see surviving today is an example of a series of genetic/proteomic/environmental changes working in concert to assure that life continues on. It is naive of you to think that a single genetic mutation results in the difference between you and a dog....there is more than that between you and your sibling....unless maybe if you are a twin.

The Russian Smalhausen introduced a bit of difficulty in using TWO kinds of notions for Stablizing Selection, in which BOTH strengthing of a mean(distribution) & affirmation of adaptabilites into an adaptation were unified. This may be the source of said confusion.

NosyNed
"But the statment:
"Most mutations are harmful or neutral" can be true AND at the same time "Most mutations are harmful" can be false."Um...okay. How about we say this instead. Most mutations are NOT
beneficial. This "little" fact is problematic for me.The mutations that are, supposedly, "beneficial" are first off, hard to tell IF they ARE "beneficial" AND they are a RARE occurrence AND even IF they are "beneficial" they can STILL disappear or not be passed on. And, Generally speaking, MOST new mutants are lost anyways, even beneficial ones.Think about that. I have and it's giving me dame bramage.
So you're talking about a "Rare" occurrence.
That's even "Hard" to detect if it even occurred to even know if it IS beneficial.
And even IF it is beneficial it can still be lost.How many times do these hard to know rare occurrences that can be lost have to happen to result in say a wingless creature to slowly evolve a wing nub (nub as in the very early stages of a "potential" wing evolving, NOT to say that a wing WILL evolve.) ? How many years would that take before something useful like a wing has evolved and has been selected for, (let alone the wing nub being selected for)? Even with 40 Billion years, the idea that these rare occurrences can evolve into what we know of the world today is still not plausible for me. ESPECIALLY when you are talking about mutations that occurs in a genetic code that is the building block of all creatures which must have also evolved (DNA) FIRST before we can even talk about any beneficial mutations. Sorry guys, but I have a tremendous problem with that, call me Krazy. Maybe someone can do the math of taking 40 billions years times all the known species we know of and multiply the figure by "x" (carry over the 1) and come out with some general idea of how many "beneficial" mutations must have occurred to result in the species of today. I'd be interested to see some formulation of that. (Math is not my strong point)"What is the net result," you may ask. Some mutations are fatal or very bad. These mutations get eliminated immediately. Some are silent and don't count. Sometimes a mutation is definitely advantageous; this is rare but it does happen. Almost all mutations which aren't silent and which aren't eliminated immediately are neither completely advantageous nor deleterious. The mutation produces a slightly different protein, and the cell and the living organism work slightly differently. Whether the mutation is helpful or harmful depends on the environment; it could be either.""Quite often a mutation occurs within a population and then disappears because the organism had no offspring or didn't happen to pass the mutation on to its offspring; this can happen even if the mutation is beneficial."Are Mutations Harmful?I'll reiterate that the "Relevant" statement in reference to the
evolutionary process would be that Mutations are mostly NOT beneficial. Right?

Then they weren't, by definition, beneficial. I don't entirely understand how you came to the conclusion that most beneficial mutations are still fatal.The question is, did the mutation allow the organism to leave more viable offspring than the competition (that is, every other conspecific)? If the answer is "yes", the mutation was beneficial, and evolution occurs. Wings don't evolve from nubs, particularly in vertebrates. In vertebrates they evolve from arms. Show me a vertebrate with both arms and wings.I don't know how they evolve in insects, but I could probably find out from one of the books my wife has. How much time do you think it would take, then? Call me strict but I think that's an erroneous use of "beneficial". If it didn't help the organism, then there's no way to say that the mutation was beneficial. Obviously, accidents happen. Not all death is selection - sometimes you get hit by a rock or something.

You know, I can understand that it is hard to grasp what is possible. It is made harder when there are so many misconceptions.One thing you should note is that each and every individual organisms is an little experiment. Each one contains some mutations. There are, at each moment on the planet, how many individuals?I don't know but even just taking multicellular life it must be around the trillions mark. Potentially benefical mutations are only rare in that a specific indivdual has a smallish chance of having one. However, they are in absolute numbers very very common.Also the split between beneficial and neutral may be a bit too sharpe. It is clear that mutations are not, by themselves, either of those. It waits on the environment to sort out which are and are not beneficial.Another problem is the idea that the mutation has to be somehow spectaculary beneficial. It doesn't. The whole process of selection is statistical. As you point out even beneficial mutations could, by pure bad luck, not make it. But the slightest extra edge could also make the difference between more and fewer offspring too. One could claim, without good evidence, that every surviving individual has shown their specific genome to be somehow beneficial. How can you discount that?There are trillions of experiments a year. These can add up to real change pretty quickly. We see how rapidly organisms can change in a very short time in the lab. The world around us is an very large, very long running experiment.It may be difficult for you to accept what can arise out of this stew of every changing organisms but simple incredulity isn't enough to refute it. All the evidence we have says that it can and more, has happened.

Moi
"And, Generally speaking, MOST new mutants are lost anyways, even beneficial ones."Crash
"Then they weren't, by definition, beneficial. I don't entirely understand how you came to the conclusion that most beneficial mutations are still fatal."Me again...
Crash, your confusion confused me
I never said that "beneficial" mutations were fatal. I said that they can still be lost. Whether they are beneficial, neutral or obviously detrimental. So says Talk Origins.Talkorigins (Richard Harter)
"Quite often a mutation occurs within a population and then disappears because the organism had no offspring or didn't happen to pass the mutation on to its offspring; this can happen even if the mutation is beneficial."Crash
"Call me strict but I think that's an erroneous use of "beneficial". If it didn't help the organism, then there's no way to say that the mutation was beneficial. Obviously, accidents happen. Not all death is selection - sometimes you get hit by a rock or something."You are one strict customer. You might want to take this up with Mr.Harter.

Look for work done by Dr. James H. Marden and Stone Flies. I ran into this last year and found it interesting. Page Not Found | Cleveland Museum of Natural History is one site, the one I remember had an animation that was well done.enjoy.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

But that only happens when the organism dies before leaving offspring. So you'll excuse me if I took what you said to mean that even benefical mutations mostly kill the organism, which doesn't make any sense.What did you mean by "lost", otherwise? Where do you think they go?

NosyNed
"You know, I can understand that it is hard to grasp what is possible. It is made harder when there are so many misconceptions."Er...what misconceptions might that be eh? I provided a nice link to the web page I got this info from so you can check it out for yourselves.As far as what is "possible" sheesh you can purty much cover a lot of subjects in that regard, don't you think? However from the scientific data about mutations, of which talkorigins addresses, it makes that "possibility" less "probable", to me at least.NosyNed
"Also the split between beneficial and neutral may be a bit too sharpe. It is clear that mutations are not, by themselves, either of those. It waits on the environment to sort out which are and are not beneficial."Hmmm...maybe, maybe not.
Ok, well you've just managed to stack the odds more against "beneficial" mutations being passed on when you include the environment factor. I'm not saying that it isn't a factor, I'm just saying it makes the "possibility" that much more difficult, shall we say.NosyNed
"Another problem is the idea that the mutation has to be somehow spectaculary beneficial. It doesn't. The whole process of selection is statistical. As you point out even beneficial mutations could, by pure bad luck, not make it. But the slightest extra edge could also make the difference between more and fewer offspring too. One could claim, without good evidence, that every surviving individual has shown their specific genome to be somehow beneficial. How can you discount that?"Sorry, I'm not too sure what you mean. I know, for me at least, I don't think that a "beneficial" mutation has to be somehow "spectacular". I'm fine with the "idea" that they might even happen. It's the "idea" that such a rare occurrence helps the argument that a bunch of them resulted in what we see today on earth, THAT'S the problem. Is it still "possible"? I guess anything's possible, is it "probable" doesn't look that way to me.NosyNed
"It may be difficult for you to accept what can arise out of this stew of every changing organisms but simple incredulity isn't enough to refute it. All the evidence we have says that it can and more, has happened."Incredulity? Dude if I may, what's the "possibility" that you'd win a million dollar lottery? 1 in something right? Now try winning it again. What's the "possibility" that you can accomplish this? I'm not saying that it "isn't" possible. But...would it be incredulous to say that I can't accept that you could win the lottery in a lifetime, say 3 times? Even though it's "possible"? I don't have any evidence that it's "impossible", however how "probable" is it that you can accomplish this 3 times in a lifetime? You're picking a random number between 40 or 50, with 40 or 50 balls that are randomly chosen among millions of people and you have to hit the right number 3 times. Try that as an experiment. However on one condition, that you give me the winnings for the 3rd ticket, since it was MY idea in the first place. You make incredulity sound as if it's something bad. I'm simply saying that the odds are strongly against "beneficial" mutations a) happening, b)difficult to confirm (if they are) c)can STILL be lost and d) or c1) the environment can be another cause for losing them. Can it "possibly" happen, perhaps, but can it account for all of what we see today, even in 45 billion years time, I don't know but I find that highly "improbable".Like I said, I'd be interested in seeing some calculations made that gives us an "average", doesn't have to be perfect, of how many of these "possibilities" must have occurred within 45 billion years time to result in what we see today. Is that even "possible"

Beneficial alleles (This is the heading the paragraph below is under)Most new mutants are lost, even beneficial ones. Wright calculated that the probability of fixation of a beneficial allele is 2s. (This assumes a large population size, a small fitness benefit, and that heterozygotes have an intermediate fitness. A benefit of 2s yields an overall rate of evolution: k=4Nvs where v is the mutation rate to beneficial alleles) An allele that conferred a one percent increase in fitness only has a two percent chance of fixing. The probability of fixation of beneficial type of mutant is boosted by recurrent mutation. The beneficial mutant may be lost several times, but eventually it will arise and stick in a population. (Recall that even deleterious mutants recur in a population.)http://www.talkorigins.org/...intro-to-biology.html#mutationNote where he says, "The beneficial mutant may be lost several times..." but more notably how he begins the paragraph.If the mutation "disappears because the organism had no offspring or didn't happen to pass the mutation on to its offspring"...means what? You lose it right? Or should I say it "disappears". They're synonymous in a sorta kinda way don't ya think?[This message has been edited by Milagros, 04-12-2004]

Here's the error in this analogy: I don't have to win the lottery three times. Somebody here in the state does, in fact, win it nearly every week. If they don't piss all of that loot away, they pass some of the benefit on to their kids.A single organism doesn't need to "win" three times, or even once: it just has to leave progeny that wins, say, once in a thousand generations in order to pass down noticeable change. Our state lottery used to say, "$4 million ain't chicken feed!" Likewise, a lot can happen in a million years, and we know of nearly 500 millions of years just since the first vertebrates.

Can you tell me the percentage of mutations that are, in any way, beneficial? I can't calculate the odds until I know this.

I actually didn't know that.Interesting. But with so many mutations happening per organism - hundreds, usually - a two percent fixation rate is still a lot. For instance, that's two of your own mutations being fixed in the population.

At very low initial frequencies, beneficial alleles can be lost purely due to stochastic, or chance processes, even if they are under strong positive selection.KC