What exactly is "Natural Selection"?

[classical_hero]

An AiG speaker visiting a cave in Australia was told by the guide about a blind shrimp which, in that lightless environment, had ‘evolved the ability not to see’. (!)

Obviously, a mutation (genetic copying mistake) causing blindness in a shrimp living in the light would normally hinder its ability to survive. However, it would not be a handicap where there was no light, and as a side benefit, the shrimp would not be susceptible to eye infections like its still-seeing relatives.

This slight advantage is enough to ensure that, after a few dozens of generations, all the shrimps will carry the defective gene, and thus will all be blind. They have not in fact evolved any abilities, they have lost one.

A loss can be a survival advantage, but it is still a loss. The evolutionary belief demands that massive amounts of new information have arisen over time; showing how information is lost or corrupted can scarcely be said to support this belief..

http://www.answersingenesis.org/creation/v23/i3/muddywaters.asp

Is this what Evolution is about? Natural selction seems to be a losing of genetic material rather than gaing of infomation.

 

[Saga of Gemini]

Nope....men WTH?? :S

Natural selection ( in my eyes not tryng to give the actual definition ) is an excuse to try to explain why animals are like they are..however it fails to answer all the important questions "how and why did that animal do that" or "how does that explain where that animal comes from" see?

 

[Perfection]

Natural selection can account for both the addition and subtraction of information.

It accounts for the addition of information by allowing the build up of succesive mutations.

To give an abstact example let's say we have a novel new structure composed of varaiations of 10 genes, each gene has a possibility of mutating into one in four genes. Under no selection it just randomly switches from one to another and it ends up taking a very long time for an organism with all 10 mutations to develop.

However if we factor in natural selection, that is we allow those that have more "good genes" better then average reproductive success suddenly the mutations are retained throughout the generations and an organism with all 10 mutations develops relatively rapidly.

 

[classical_hero]

Natural selection can account for both the addition and subtraction of information.

It accounts for the addition of information by allowing the build up of succesive mutations.

To give an abstact example let's say we have a novel new structure composed of varaiations of 10 genes, each gene has a possibility of mutating into one in four genes. Under no selection it just randomly switches from one to another and it ends up taking a very long time for an organism with all 10 mutations to develop.

However if we factor in natural selection, that is we allow those that have more "good genes" better then average reproductive success suddenly the mutations are retained throughout the generations and an organism with all 10 mutations develops relatively rapidly.

Every time there has been a mutation, it has always taken genetic material from it, never added to it. Give me an example of a mutation that has added genetic material to the gene pool.

 

[Sophie 378]

Gene duplication. Easy peasy! As soon as you've got a duplication, mutations in one of the duplicates gives you new proteins. Either God has no imagination at all, or most of the proteins I've been studying this year have arison through gene duplication and mutations.

 

[Perfection]

Natural selection ( in my eyes not tryng to give the actual definition ) is an excuse to try to explain why animals are like they are..however it fails to answer all the important questions "how and why did that animal do that" or "how does that explain where that animal comes from" see?

Natural selection is certainly part of that explination. Certianly just saying "natural selection did it" is not a valid explination but by demonstrating how natural selection favored each step we can see how how the proposed mechanism worked.

For example this paragraph[url] on the evolution of eyes shows how incremental steps provided a selection advantage and shows how a noval feature could arise over time.

Edit:

@Classical, Sophie handled your question quite well I feel no need to add

 

[Bill3000]

I forgot the name of the segment, but there is an intron that is infamous for duplicating itself within the human genome in various places. Human diversity can be measured through the comparation of where each part of the duplicated segment exists.

An addition error is one of the most fundamental mutations, by the way.

Natural selection is only an excuse to those who do not fully understand it. This is not a loss for the shrimp, as it has no need for it. Diverting the energy from a useless function to other functions is a good advantage. It's the same type of reason why our appendix has no function anymore.

 

[Shaihulud]

Every time there has been a mutation, it has always taken genetic material from it, never added to it. Give me an example of a mutation that has added genetic material to the gene pool.

It has given feathers to dinosaurs, Wings to birds, eyes to complex cell animals and various other much more complex organelles. One reason why the shrimp lost its eyes may be the enviroment it lived in was an extreme one with scarce resources. Eyes that requires complex brain computation is a liability in this situation, thus the shrimp eventually breed out teir eyes.

The genetic information for eyes still exist in the shrimp, im pretty sure that the shrimp will occasionally spawn with eyes as a mutation. Its propably a couple of inhibitor gene or somesuch stuff that prevents the eyes from manifesting during its larvae stage. Expose the shrimp to the light and several generations later, viola! Shrimps with eyes again, assuming they don't get all killed off!

 

[Saga of Gemini]

Natural selection is only an excuse to those who do not fully understand it

Do you? explain me how does that gene loss explains me how the shrimp became a shrimp? BTW Natrual slection is undenyable we see it everyday but it dosnt explain the how something "came to be"

 

[Mr. Blonde]

For instance through junk DNA:

Our and the DNA of most species contain so-called junk DNA that is under normal conditions not expressed into proteins. Mutation can cause this DNA to be expreessed - resulting in additional proteins.

If you really want to get involved in Gene expression, evolution and the functioning of your body on a molecular level I would recommend Stryer: Biochemistry. It contains lots of proven information on the topic you don´t know too much about according to your statement.

For the records: I am working on a PhD in chemistry and I went through Biochemistry at Universitiy level so I know a thing or two about the topic.

 

[Bill3000]

Do you? explain me how does that gene loss explains me how the shrimp became a shrimp? BTW Natrual slection is undenyable we see it everyday but it dosnt explain the how something "came to be"

I don't claim to be an expert in biology. I'm a mere sophomore in my major of Biomedical Engineering. That isn't an excuse for those who try to criticize science without understanding it, however.

If natural selection is undenyable, why is it denyable to allow its logical extension?

To answer your question, the answer is that what we call a shrip is merely a anthropocentric definition of a process that does not exist rigidly. There are many different kinds of shrimp, each with their own large genetic variations. Evolution is a gradual process, and taxonomy is rather rigid in a process where the line is blurry.

I'd like to point out that the form of taxonomy I am talking about is casual taxonomy. What we call a domesticated cat to be a "cat", rather than Felis silvestris catus (Linnaeus, 1758). Casual taxonomy is not useful in evolutionary biology.

 

[Rhymes]

Do you? explain me how does that gene loss explains me how the shrimp became a shrimp? BTW Natrual slection is undenyable we see it everyday but it dosnt explain the how something "came to be"

If you take a shrimp, make it evolve during 100000 years, what do you think will happen? First, it will grow some kind of extra flipper on a mutation or something. Then some other mutation will give it an extra eye, then... then.. then... untill it cant be called a shrimp anymore.....

 

[Sophie 378]

If you really want to get involved in Gene expression, evolution and the functioning of your body on a molecular level I would recommend Stryer: Biochemistry. It contains lots of proven information on the topic you don´t know too much about according to your statement.

Stryer rocks. It's much easier to read than most textbooks. Any reputable university-level science library ought to have a few copies. Fifth edition is big and green, ISBN 0-7167-4684-0. Jeremy M Berg, John L Tymoczko and Lubert Stryer. Published 2002 by Freeman. It even has a chapter on biochemical evolution.
(I'm in the final year of a Natural Sciences degree, based on Biochemistry and Chemistry.)

 

[Tank_Guy#3]

It basically translates to survival of the fittest. Natural selection is those best suited to the environment survive, who went through the natural selection process, while those who aren't most suited can sustain, but in most cases die.

But the most simple version of this is that best suited traits live on, obsolete or traits no longer useful die out. Thus, survival of the fittest.

 

[Tank_Guy#3]

Sorry double post.

 

[FredLC]

Is this what Evolution is about? Natural selction seems to be a losing of genetic material rather than gaing of infomation.

Actually, the term "evolution" has a meaning which is misleading to most folk. A better naming, IMHO, would be "theory of adaptation".

This, because the name evolution evokes a notion of "development" which can happen, but is incidental, to the manner species relates to their environment.

The example of the shrimp here given - which is also a common issue relating to "deep water fishes", also environments without light - demonstrates perfectly well two things - the workings of the evolutionary system and the narrow-mindedness of the ones opposing it.

It's common knowledge between those who accept the evolutionary table that life has begun in the water (as, being a fluid environment, it was a much easier location for substances to flow before the first circulation systems developed), later moving, than, to dry land.

Obviously, this movement had a cost, which increased more and more as animals moved away from water. The hability to survive indefinitely in a water environment was diminishing, until the point where these animals couldn't do it anymore. From a certain point on, many had to live in land, as living in water would be fatal.

But there was also gain tp these creatures, in escaping competition to less crowded terrain, gaining the hability to move where others could not, having new sources of food. Some species learned to live under the earth where they were safe from predators, some learned to fly, there is even one which managed to become intelligent.

So, in total, all modifications meant a loss, as some caractheristic once had gets lost... but the net result is a gain, for the profit, considering the conditions met, is larger (maybe much larger) than such loss.

Eyes are a prime example. They are highly specialized external organs. Their specialization makes them very fragile and susceptible to harm and desease, and difficult to cure when somehow injuried. However the advantage they provide - to see - more than justifies the cost of having them.

If, however, they are rendered useless for the lack of light - a condition sine qua non for their functionability - than they become a drag; a useless source of pain and harm, where desease enters more easily and where both predators and preys can strike with greater success.

This leads to a diminished survival potential in comparison to other animals of the species that lacks eyes for some genetic malformation. The former disadvantage, due to a specific circunstance of the environment, becomes the new advantage. These animals, than, become more sucessful in the fight for survival, and hence, gets an increased shot at sucessfully reproducing. The rate of *blind* animals in function of the *total* animals increases steadly, until they become the norm, instead of the exception - a factor called "genetic derivation".

Although it's likely that these animals would evolve another kind of sensorial solution (which may even be less efficient *globally* than sight, but that works better in the conditions they face), let's ignore it and say they would merely become blind to handle the common misconception that "evolution means betterment".

Not necessarily; evolution merely means the sucess of the caractheristics that better fits the environment. Such caractheristic can mean a step back in relation to a more pompous previous trait, but it will be more appropriate to the challenges of the future of that particular animal considering the circunstances it have been facing.

So natural selection is so because, literally, it envolves the selection of appropriate traits in response of a pressure which comes from natural conditions (environment). It may mean loss or gain exclusively, or, more likely, both at the same time.

Does this answers the question?

Regards .

 

[classical_hero]

It might come as a shock to but before Darwin famous stated that Evolution was a result of Natural selection, there were Creationists who believed in it from a nonevolutionary way. It might shock some people but Darwin did not come up with this revolutionary thought.
http://www.thedarwinpapers.com/oldsite/Number2/Darwin2Html.htm

Francis Hitching mentioned that Eiseley had chronicled quite substantial portions of Darwin's writings
that were nearly "word for word identical between Darwin and Blyth"" although Blyth's ideas preceded Darwin's publication of The Origin by over twenty years (I do not necessarily agree with Eiseley on the strict word for word comparison, however compare this from the Magazine of Natural History in 1835, which Darwin read on the Beagle, with Darwin's earlier chapters on natural selection in his Origin).

Later on in the article here is an admission from this group that Blyth was a creatonist.

William Wells had actually written of natural selection in 1813 (as had many others, however it was Blyth's writing that Darwin clearly was impressed by during his voyage, and it was Blyth who saw natural selection in a creationist context) but Darwin claimed that he was unfamiliar with Well's writings at the time of the original publication of The Origin of Species.

If you want to see what Blyth had to say then read this. http://www.wku.edu/~smithch/biogeog/BLYT1835.htm
This is the complete work that Blyth famous wrote and it appears that Darwin copied alot of his work from.

As you can see it is clear that natural selection is neither for or against either creation or Evolution, because both have laid claims to it. Natural selection has been used from a Creationist background and Evolutionists background. Just like most things regarding Creation/Evolution, it is a they way how facts are percieved that separates the two groups.

 

[Pontiuth Pilate]

Every time there has been a mutation, it has always taken genetic material from it, never added to it. Give me an example of a mutation that has added genetic material to the gene pool.

Hox duplication.

Next time, know what you're talking about.

 

[FredLC]

It might come as a shock to but before Darwin famous stated that Evolution was a result of Natural selection, there were Creationists who believed in it from a nonevolutionary way. It might shock some people but Darwin did not come up with this revolutionary thought.
http://www.thedarwinpapers.com/oldsite/Number2/Darwin2Html.htm

It may come as a shock as well, but the notion that creatures change over time was a suspicious from the naturalists long prior to darwin, and the relevant inovation of the "The Origin of the Species" was exactly to offer a natural theory to explain this which was implied from the collected data, basically removing the need for divine intervention.

So, not many shocking news there...

 

[The Last Conformist]

The notion of "information" is pretty unhelpful when discussing genetics, particularly when the speaker doesn't deign to specify what precisely he means.

I could reproduce Dembski's "proof" that natural selection increases information, if anyone wants me too. It's kinda amusing.

As for mutations that increase genetic material, they're legio. Insertions, duplications and polyploidy are all over the place.