How can one tell that the developed throats and brain are a result of mutations?
Because that's the only observed mechanism for the introduction of genetic material into the gene pool of a population.
The alternative is that humans have always had these genes because humans were created with them, but we've never observed a mechanism that can create an organism wholesale from scratch.
Isn't it true that mutations are rather rare?
No, they're quite common. You probably have between 50 and 500 (rough estimate) mutations of your very own. Obviously they're neutral ones, or else you'd notice. Then again there's the occasional human with a noticable mutation, like a lack of wisdom teeth.
How could the evolution of a species occurred if only a few, or a single species got that genetic mutation? Wouldn't the greater population of other (birds for example) make it so that the new mutated form would never get a chance to gain into a majority
Sometimes that happens. But a beneficial mutation is one that allows that organism to leave more progeny than it's competitors. Therefore by definition the mutation will become more common because individuals with the mutation are outcompeting and outreproducing the individuals who lack it.
Remember also that it isn't "muties vs. normals." The individuals without the mutation don't band together against the individual with it. They're competing against each other, too.
Even then, isn't it a bit extreme to say that all evolution happened due to reproductive isolation (maybe you don't say this, but that's what you seemed to imply)?
All speciation happens as a result of reproductive isolation. Huh, I'm surprised you missed that; I thought I had been pretty clear about it.
Evolution is when allele frequencies change within a gene pool. Speciation separates gene pools permanently (which can change allele frequencies.) Reproductive isolation interrupts gene flow, which allows speciation to occur.
And please pardon my ignorance, but how is it that the environment determines the outcome of mutations?
By selection. Beneficial mutations are mutations that are selected for. Harmful mutations are mutations that are selected against. Of course, it's not like the environment is picking and choosing, any more than the roulette wheel "chooses" where the ball lands. Selection is just the name we give to the observation that organisms adapted to their environment tend to leave more offspring than the ones that don't.
For instance - what if you had a mutation that gave you thick, insulating fur? Is that a beneficial mutation or a harmful one? Kinda depends on whether you live at the North Pole or in Africa, doesn't it?
Adaptation occurs within one generation where as evolution, even on its smallest scale, only happens through heredity. I've had creationist friends that played word games where evolution didn't happen but "adaptation" did. Where if they really understood the definitions they would realize they didn't know what adaptation meant.
Most mutations are nuetral. Not helping or harming an organism, and this is one of the ways we trace common ancestors...by identifying these nuetral mutations.
As far as beneficial mutations...sickle cell anemia is sort of beneficial if you happen to live in an area where malaria is prevalent.
[This message has been edited by SweeneyTodd, 04-07-2004]
DC85 "This is false every Creature has some kind of Mutation.. so most are Just not Visable and don't effect the creature either way..." ------------------------------------------------------------------------
With all due respect DC85 but what you've said is not entirely true. Here's a Quote by Edward E.Max on the Talk.origins site, he clearly states that,
"While it is true that most mutations are either harmful, as suggested by the creationists, or neutral, the creationists gloss over a crucial fact: beneficial mutations do occur, though they are very rare."
Here's the site so you can confirm it yourself, I don't want to be accused of taking anyone's statement out of context. However I'm only providing this so you won't take "MY" word for it. http://www.talkorigins.org/faqs/fitness/ Specifically under the heading "1.2.1 Are all mutations harmful?"
But notice he does say that MOST ARE "harmful" or "neutral". I'm not talking about any "beneficial" ones, I am ONLY addressing your response where you claim that "This is false...." to the statement made earlier that "Most mutations are harmful".
Also DC85 , what do you mean, "most are not Visable...?" Visible to the naked eye? Microscope? Electron Microscope? The reason that confuses me is because mutations "HAVE" to be, somehow, visible otherwise, how would we even know if one occurred? Right?
[This message has been edited by Milagros, 04-07-2004]
Milagros - mutations can be, and frequently are, changes in DNA that lead to no change in the amino acid that is coded for. Thus, they are "invisible" as far as the organism is concerned: only DNA sequencing can detect them.
I Have some Problems Expressing things... Like Instead of Creature I should have used Organism and Instead of not Visible I should have said almost Undetectable... little mistakes give me problems... I Get yelled at by my Professor all the time.
[This message has been edited by DC85, 04-07-2004]
quote:Also DC85 , what do you mean, "most are not Visable...?" Visible to the naked eye? Microscope? Electron Microscope? The reason that confuses me is because mutations "HAVE" to be, somehow, visible otherwise, how would we even know if one occurred? Right?
Most mutations are neutral. Usually, this refers to mutations of the DNA in areas that do not code for a protein or are not involved with expression of a protein (eg, promoter regions). Also, neutral mutations can change the amino acid sequence of a protein but the activity and specificity of the protein is unaffected. Obviously, without sequencing the DNA or amino acid sequence of the protein these mutations would not be apparent. So yes, they are visible, but not visible with respect to the functioning of the organism, either as an increase in fitness or a decrease in fitness.
Here is a question for the fold. If a mutation causes a change in phenotype, but is neutral with respect to fitness, can this also be considered a neutral mutation? I would assume that this type of mutation would be considered neutral, but was wondering what the uber-experts thought.
It seems that it is generally agreed upon that most mutations are neutral, some are harmful, and even fewer are beneficial. It has been said that beneficial simply means that the organism can reproduce faster than its counterparts.
How might one define a mutation? I understand it is the change in allele frequencies, or something like that. What are some common day examples of beneficial mutations in humans? Do we know of any? Do mutations really occur fast enough to lend credibility to the theory of evolution? In other words, are there enough beneficial mutations to explain why humans evolved so quickly into what they are today? Aren't most mutations sterile, or unable to reproduce?
I thought that mutations more often take things away than provide new, helpful things. For example, when mutations take out teeth, that is not exactly beneficial, is it? How would such a thing help faster reproduction (if indeed that is the definition of beneficial)? It seems like when people refer to "beneficial" they mean two things: Helpful to the organism, and able to make reproduction faster and more numerous. Is this equiviating on the term?
And crashfrog, I am sorry I misunderstood. What would you say is the difference between evolution and speciation? Can evolution occur without speciation? If so, what is the organism evolving into that is new? Can there be any significant evolution within a species? Finally, are evolutions and mutations somewhat synomous, or is there no direct relation?
What are some common day examples of beneficial mutations in humans?
A few that have shown up on this very forum before: * two different mutations, one African and one West European, that appear to give near-immunity to AIDS * a mutation in Italians in a village that make the mutants nearly immune to high-cholesterol problems * a cluster of mutations which allow adults to continue to digest lactose and thereby drink milk * the hemoglobin C mutation, which, like sickle-cell, give resistance to malaria, but which usually is otherwise symptomless.