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#69 maikeru

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Posted 15 January 2011 - 05:56 AM

If there was a fully random change within all the genes, more can wrong than right, since even important systems would be free game for bad choices. Take any enzyme and tell me how many ways to make it worse and how many ways to make it better? Which has more options?


It is "free game" and "open," but in more ways than you realize. Evolution has a guiding hand which often takes care of "wrong" choices (note that there really is no "wrong" or "right" in evolution, I'm using the terminology to simplify the discussion)--we call it Natural Selection. Individuals (and their collective genetic package) which acquire lethal or too many detrimental mutations have natural selection selecting against them, and hence are less likely to be able to reproduce and pass their detrimental mutations onto future generations. So long as natural selection applies pressure to shape the gene pool of the population through the generations, your supposition is basically moot. In fact, because of natural selection and other factors at play in evolution, this creates a standard for surviving organisms to be well adapted, and thus increasingly successful, at what they do, which are all things reproduction, survival, and transmission and multiplication of their "fit" genes. The end result is a population of individuals carrying genes with mutations/variation who have more right than wrong.

#70 freeztar

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Posted 15 January 2011 - 09:24 AM

Paley's argument was defeated even long before Dawkins, in The Origin by Darwin.


Indeed. But Dawkin tore it up. :)

#71 HydrogenBond

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Posted 15 January 2011 - 11:00 AM

Selective advantage is dependent on the environment. If you change the environment the conditions for advantage will change. For example, extra thick fur may be an advantage in the tundra, but may not create an advantage at the equator. The extra thick fur is only one variable among dozens of other randomly changing variables. It may define fitness in an environment, but not necessarily overall fitness in terms of efficiency.

For an example, if you look at the peacock, natural selection and breeding favors males with large colorful feathers. Theoretically, even a peacock with regressive internal body systems, as long as he can look good and sing the right song, he will have selective advantage. The peacock is not suitable for making sure the most fit genes move forward through natural selection. Yet if does well since in his case natural selection is more of a secondary variable.

If there is enough internal checks and balances, natural selection can be based on a show of color.

#72 CraigD

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Posted 15 January 2011 - 11:52 AM

The role of gene “mixing” vs. mutation in evolution

Not exactly. What I was trying to say, a completely random model for mutations, would lead to the extinction of life. Therefore evolution does not follow this schema, since extinction is not the case. I am not denying evolution, rather I do not fully accept a fully random bio-chemical mechanism.

HBond, I believe you have the incorrect impression that the only way inherited traits of biological organisms change from generation to generation (which is precisely what the term “biological evolution” means) is due to mutations.

As Wfwfq noted, evolution (of plants and animals, I should qualify) is mostly by chiasms, the mixing of parents’ genes to form a genetically unique new child, not mutations, random and usually inconsequential or non-beneficial changes to parents’ germline genes.

In short and rough analogy, evolution is more a process of remixing the same genetic “words” than of introducing new words. Because most observable traits – appearance, behavioral predisposition, etc. – depend on many genes, this mixing of un-mutated parents’ genes produces traits not seen in either parent.

Even many organisms that reproduce by cloning have mechanisms for “mixing” genes among individuals (termed “horizontal gene transfer”), so their evolution is still more mixing driven than mutation driven.

Examples of clonally reproducing species that have a lot of LGT are bacteria, a very successful collection of species which exchange genes very promiscuously via plasmid exchange. Examples of clonally reproducing species that don’t have a lot of LGT are ameoba, where each species can realistically be considered not a succession of parent-child generations, but the same, very long-lived, individual.

The blind car builder does not reflect the evolution we see. The cell would not have evolved proof reading enzymes if life had random in mind. There is an advantage to less random or this mechanism would not have evolved.

I hope you can see from this explanation, HBond, that the random mixing of mostly un-mutated parents’ genes does reflect the evolution we see, and explain why “proof reading” functions in gene transcription enzymes (eg: DNA polymerase) are consistent with random (vs. artificially or “intelligent”) processes described in theories of evolution. There is advantage to less random mutation (which transcription factors like DNA polymerase assure) yet also advantage to lots of random mixing, which chiasma and LGT assure.
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#73 Qfwfq

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Posted 15 January 2011 - 12:53 PM

Indeed. But Dawkin tore it up. :)

nah darwin put it into a mill and reduced it to an impalpably fine powder

at that point, no chance of tearing it up :roll: :P :hihi:

:dog: Wf wf wf wf, qrrrr....

#74 maikeru

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Posted 15 January 2011 - 08:59 PM

Selective advantage is dependent on the environment. If you change the environment the conditions for advantage will change. For example, extra thick fur may be an advantage in the tundra, but may not create an advantage at the equator. The extra thick fur is only one variable among dozens of other randomly changing variables. It may define fitness in an environment, but not necessarily overall fitness in terms of efficiency.

For an example, if you look at the peacock, natural selection and breeding favors males with large colorful feathers. Theoretically, even a peacock with regressive internal body systems, as long as he can look good and sing the right song, he will have selective advantage. The peacock is not suitable for making sure the most fit genes move forward through natural selection. Yet if does well since in his case natural selection is more of a secondary variable.

If there is enough internal checks and balances, natural selection can be based on a show of color.


When it comes to evolution, efficiency and perfection are relative.

#75 Rade

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Posted 18 January 2011 - 09:53 PM

I request that this thread post be blocked. We have moved well past the OP question about why vertebrates do not have red blood cells that reproduce. Hydrogen Bond has not posted any new questions about red blood cells for many days, he now shifts the topic to creationist arguments against evolutionary theory. The last 10+ posts now deal with basic evolutionary theory, not red blood cells.