Gawdzilla Sama
TImeToSweepTheLeg
Creationist argument about DNA and information
- Thread starter barehl
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A friend of mine posed that question to me the other day and claimed Dawkins couldn't answer it. He also asserts that mutations can't be passed on and always either kill an organism (or cause catastrophic changes) or render it sterile.
I've always thought that the changes (or mutations if you will) that drive evolution happened during reproduction due to combination errors of the parental dna. That makes sense to me as I don't see that an organism will suddenly exhibit different traits such as a larger beak or less hair during it's lifetime. But that's actually what I think my friend is driving at to disprove evolutionary theory.
Anyone have any good links about this?
I've always thought that the changes (or mutations if you will) that drive evolution happened during reproduction due to combination errors of the parental dna. That makes sense to me as I don't see that an organism will suddenly exhibit different traits such as a larger beak or less hair during it's lifetime. But that's actually what I think my friend is driving at to disprove evolutionary theory.
Anyone have any good links about this?
That's either disingenuous or stupid. Selective breeders have often used mutations that they have found useful and bred for them.
The Long Term Evolution Experiment has had at least one highly novel mutation occurring in E.Coli
Elind
Philosopher
The most evolutionary diverse and deliberately mutated animals on the planet are dogs, probably followed by cats and chickens.
I wouldn't say deliberately mutated but there are also many neutral mutations. I can roll my tongue whilst my wife can't. The difference is gentic and hence ultimately due to a mutation but it doesn't matter either way.
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Elind
Philosopher
Ok, I rephase. Deliberately expressed mutations.
It's creationist!!!! He also refuses to acknowledge there's no difference between creationism and ID.
Thanks for the link, I'll check that out. But doubtless he'll counter with the micro/macro evolution trope.
If they accept micro evolution, then that relies on mutations.
Rincewind
Philosopher
Or goddidit?
turingtest
Mistral, mistral wind...
Their movable escape hatch to keep from ever being cornered by contradictions or specifics- a god who can do anything at all isn't going to be bound by the need for evidence of science. Which, to me, is sort of irritating- if you're going to spend your time pretending your argument is based on evidence, but end it, whenever that fails you, by resorting to a premise that needs none, it would have been more honest, at least, to start that way.
Elind
Philosopher
In a similar vein go the science deniers on AGW, except then it's not a god's will but the conspiracy by NASA and any other science organization that disagrees with them. Quite impossible to have a rational discussion because, as you say, they simply discount any recognized science if they disagree, and their disagreement is simply based on something read on a blog and if an opponent can't prove them wrong, starting from first principles in a few sentences, then it is dismissed.
I find it such a strange mental state, bordering on a form of insanity. Of course they say "back at you".
Here's a link if you are interested.
http://www.examiner.com/article/new-mann-made-global-warming-study-is-scientifically-valueless-paper
No they don't. The half truth is that 'descent with modification' does not always require de novo mutations. Recombination can greatly impact a population with no de novo mutations. This type of evolution is limited by Mendelian segregation among other things. However, it can produce significant changes of a population in a few generations.
When I say allele, I am talking about the most general concept of allele. By allele I mean a gene at a particular site on a chromosome. So I include bacteria and asexual organisms. Bacterial populations also change by recombination through lateral gene transfer.
Creationists will claim that lateral gene transfer is 'recombination', not a 'mutation'. This is only semantics since changes brought about by lateral gene transfer are every bit as much evolution as changes brought about by de novo mutation.
The scientific consensus is that ALL alleles originated in de novo mutations. Therefore, one can extrapolate that to 'evolution requires mutations. However, one can breed a subpopulation and change the gene frequency distribution without a de novo mutation changing a single allele. Introductory textbooks on evolution often present such scenarios because this is the easiest to analyze.
The Hardy-Weinberg hypothesis is that allele frequency distributions in a large population don't change without natural selection. You can't use the Hardy-Weinberg hypothesis without making the assumption that there are no de novo mutations. One of the limitations of the Hardy-Weinberg hypothesis is that it can't be valid if the rate of de novo mutation is high. Discussion of the Hardy-Weinberg hypothesis can lead some students to believe that de novo mutations can't survive. This is wrong.
What limits evolution without de novo mutation is Mendelian segregation. Breeding often requires an inbred population. However, alleles tend to segregate in an inbred population. The maximum limit of this type of breeding are lineages where each gene is homozygous. Even if such a lineage is fit, evolution can't go further than that without de novo mutations. Thus, the Creationist can cook the data by claiming that evolution can't go past the Mendelian segregation limit.
Neither microevolution nor macroevolution have a formal definition agreed on by scientists. Hence, Creationists can define microevolution as being the changes brought on by recombination and lateral gene transfer. A Creationist can also claim that neither is a mutation. Two viruses can combine to form a new virus that jumps across host species.
Macroevolution occurs by de novo mutations and recombination working together. The Creationist will claim that this is not evolution because no de novo mutation was involved. Any change that can't come about by a de novo mutation is macroevolution. So when a scientists provides an example of evolution occurring over a historic period of time, they ask to show the de novo mutation.
The Creationist can further cook the data by narrowing the definition of mutation. Many changes associated with macroevolution are thought to include gene duplication. Gene duplication is one type of de novo mutation thought to contribute to macroevolution. I have heard Creationists claim that gene duplication can't influence macroevolution because it isn't really a mutation.
They claim that gene duplication can't make a large change in gene frequencies. Obviously this isn't true, since a large change can come about merely by duplicating an allele enough times. A single gene mutation has a small effect. The accumulated effect of repeated gene duplications is huge. The allele itself is subject to other types of de novo mutations. So even if one defines mutation to exclude gene duplications, the gene duplication is still a significant variation in the Darwinian sense.
So basically it is a matter of semantics. By redefining mutation, one can reject any major change that can contribute to macroevolution. It is word game.
Rincewind
Philosopher
I agree!
Oh, but Behe has already refuted Lenski’s experiment and this particular mutation. He claimed the change isn’t a mutation and that the phenotypic effect isn’t novel.
He is wrong, of course. However, if you should be aware of the most common false arguments.
Here is the ‘its not novel’ argument.
http://sandwalk.blogspot.com/2013/12/how-do-creationists-interpret-lenskis.html
Behe
‘If the phenotype of the Lenski Cit+ strain is caused by the loss of the activity of a normal genetic regulatory element, such as a repressor binding site or other FCT [functional coded elements], it will, of course, be a loss-of-FCT mutation, despite its highly adaptive effects in the presence of citrate. If the phenotype is due to one or more mutations that result in, for example, the addition of a novel genetic regulatory element, gene-duplication with sequence divergence, or the gain of a new binding site, then it will be a noteworthy gain-of-FCT mutation.’
The argument is that because the bacteria may have lost some capability in gaining the new ability, this change isn’t really ‘novel’. Therefore, it is ‘microevolution’ rather than macroevolution. This argument leads to absurd conclusions.
The evolution of the human brain has to be considered microevolution. Natural selection has lead to a bigger brain in a bigger skull. However, humans have lost reproductive ability because of the larger skull. Labor is always hard and slow, even with a single birth. A woman can’t have simultaneous and multiple births past four without difficulty. The regulatory genes that suppress the growth of the skull have been repressed. Therefore, when humans evolved from Ardipithicus to Homo sapien, they lost FCT function.
Ceteceans (whales, dolphins, porpoises) are marine animals supposedly descended from land animals by microevolution. They swim very well in the open ocean but can’t walk on land. The mutations leading to the evolution of aquatic whales thus resulted in a loss of FCT function.
Behe also seems to have jumped the gun. The two de novo mutations that apparently lead to the new citrate metabolism were a gene duplication followed by the hijacking of a promoter from another gene. So even by his standards, the is a gain-of-FCT mutation.
http://sandwalk.blogspot.com/2013/12/how-do-creationists-interpret-lenskis.html
Behe
‘After an enormous amount of work, having sequenced the genomes of many clones along the lineages that led to the ability to use citrate, as well as lineages that never did, and testing the phenotypes of identified mutations, Blount et al. have now reported that Behe was largely right. The key innovation was a shift in regulation of the citrate operon, caused by a rearrangement that brought it close to a new promoter.’
http://sandwalk.blogspot.com/2013/12/how-do-creationists-interpret-lenskis.html
Blogger
‘It's important to recognize what the IDiots are conceding. They admit that Lenski's long term evolution experiment does lead to evolution of a new strain of cit+ E. coli. This is a gain-of-function phenotype no matter how you try to spin it differently. The new function is the result of an entirely new gene formed from the fusion of two genes, rnk and citG. This, in turn, creates a new operon where a second copy of the citrate transporter gene (citT) is under the control of a second copy of the rnk promoter.’
More evidence that a scientist should politely listen to a woo woo even when he is wrong. You never know when the woo woo has caught a half truth.
Behe is claiming that total evolution (TOE) requires the gain of a new function without loss of any other function. It seems obvious to me that this is improbable compared to the gain of a new function with loss of another function. However, the environment is highly inhomogeneous. The loss of an old function does not have the same impact all throughout any given habitat. This is why evolution usually manifests as cladogenesis rather than angiogenesis. Species branch rather than change without branching precisely because not all parts of a habitat are the same.
Elind
Philosopher
I don't know all the big words in this, but isn't it true that "functions" (whatever they may be, eyes, skin color, etc) are lost all the time, although not necessarily "lost", just not expressed?
This is incorrect. Old school breeders did not purposely 'mutate' their animals and plants. The de novo (first generation) mutations were entirely random. The mutations probably would have occurred even if there were no human breeders present.
The old school breeders selected descendants of these de novo mutations. Most of these descendants were not first generation descendants of the creature that was originally mutated. Recognizing the first generation (de novo) mutations is somewhere between difficult and impossible. The selection usually occurred generations after the de novo mutation, when the mutated gene has spread out a bit over the population.
The changes were brought about by the accumulated effect of numerous de novo mutations usually selected long after the de novo mutation occurred. The breeder has no evidence that the traits he selects came from a recent de novo mutation. The breeder did not cause the mutation. He selected the mutation.
The explosive growth of biological technology has changed that situation a bit. Now, scientist can cause a de novo mutation. Maybe the first use of controlled mutations were with the compound choline, which causes chromosome duplication. Later on scientists learned to manipulate DNA using other means.
These new methods of causing mutation are not completely random, so we shouldn't use them as typical examples of mutation. However, these techniques STILL have a random component. Furthermore, some of these techniques involve processes that are naturally occurring. So there is no reason to dismiss any sort of mutation as not showing macroevolution.
The claim that breeders mutated their material is a rhetorical trap. The Creationist could claim that such mutations do not occur without a mind intentionally forcing the mutation in a certain direction. However, this is false.
You have to be careful about terminology. De novo mutations usually occur without the benefit of direct intention. De novo mutations occur all the time, even in the same individual. The effect of most de novo mutations are difficult to detect even when the individual survives. However, they are always subject to some form of selection even when they are undetected by the human population.
So animal breeders don't select mutations. They don't cause mutations. I have seen such poor hypotheses made by even skeptical people. The reason that de novo mutations are said to be random is because there is not mind that directly influences them. Any selection process after the first generation is by definition NOT random.
Furthermore, most animal selection has until recently (last few thousand years) been unconscious. The mind of the breeder selects wide outcomes, not specific traits. A shepherd may feed a dog that chases his sheep in the right direction, for example. He doesn't select on any one sequence of DNA. Any sequence of DNA that produces the desired phenotype gets selected. Since there are many sequences of DNA that can cause the desired phenotype, the chances of selecting one such individual is relatively high.Unconscious selection is not design. The shepherd does not design the sheep dog. So until recently artificial breeding was not design in the engineering sense.
Gawdzilla Sama
TImeToSweepTheLeg
We used to swim in the ocean, fins and gills. Those features have lost their functionality. But we still have seawater in our veins. And we still reproduce by sperm and eggs, just like the fish.
blutoski
Penultimate Amazing
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Some are completely lost, although we see evidence of them. Vitamin C synthesis in humans is an example our ancestors could synthesize vitamin C, but we can't. Even if the gene was expressed, it's broken now.
You might be looking for the word 'vestigal' as well, to describe the degraded functionalities.
Again, one has to be careful with the terminology.
The organs are not the same as the function. A 'function' is something that an 'organ' does. Eyes are an organ, not a function. Seeing images is a function of the eyes. Another function of the eyes is determining the time of day by the amount of illumination. Yet another 'function' of the eye is display and communication.
A gene network can 'express' an organ. So I guess an organ can be expressed. A de novo mutation in one regulatory gene of a gene network can stop the organ from being expressed, even though most of the gene network is unchanged.
An accumulated change in the timing of a gene due to natural selection is referred to as heterochrony. For instance, a shift in the position of a gene on the chromosome can change the timing of expression so the organ doesn't grow as fast as it did in previous generations. This type of mutation involving just a shift on the chromosome can be very small. Of course, a dozen small shifts in position can make one very large shift in position.
So if the shrinking of the organ makes an organism fit in a new environment, then the organ will shrink. However, the organ is not likely to shrink until it is in a new environment where the organ causes a disadvantage.
Natural selection can maintain a 'function' in a specific environment when the function has been optimized by natural selection. However, if the organism moves out of its environment then de novo mutations will make degrade the function.
Gene networks that optimize an organ contain many genes. So any de novo mutation of one of the genes can make the organ function with less efficiency. So under some circumstances the function can disappear with relative speed.
The organ does not disappear as fast as the function. The organ does not have to work efficiently in order to exist. The anatomy can contain an organ even when the timing is such as to make the organ nonfunctional.
Elind
Philosopher
Yes, taken literally. I should have been more specific. I did not mean create mutations but select for them. Life has had billions of years to accumulate mutations and some are simply sitting in a closet somewhere waiting to be called, and probably not for the first time.