SNAKE! ahhhh, it’s a snake!
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Is there a GQ scoreboard for speed of posting thought-out responses, nether snarky nor stichomythic?
I nominate this one.
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So the organism can be “intelligent” enough to design this elaborate switch mechanism . So you are saying :
A> The organism can actually - Analyse what the problem actually IS
B) Determine or select a workable solution to the problem
C) Turn the corresponding switch on in the genetic sequence
Mangetout earlier predicted that steps A and B are impossible or are in conflict with evolution theory. Who is right ?
Agreed random mutation is a much simpler theory. On one end is random and the other end is totally directed - can the truth be somewhere in the middle ? Is there evidence to rule this out ?
So say there are 100 possible mutations. And we observe that all of these possible mutations occur with the same frequency ? Where can I read such a paper ? ( - I have access to all major journal (Sciencedirect and the like) ) - so feel free to cite.
That sounds like the physicists who knew about the wave nature of light saying, so far there’s no suggested mechanism for light behaving like a particle. Agreed, but is there data showing that it can be ruled out ?
Agreed. But do you admit that the role of selection will be minimal in the first 6 hours ? Besides, genetists could always design an experiment to reduce or eliminate the effect you described. Just like Mendel selected pea plants for a particular reason and the fruit fly is chosen for some of the same reasons. (i don’t remember the exact reason but they were chosen to reduce this sort of noise in the experimental measurement).
Me, of course 
(and, in this case, also Mangetout).
No, the existence of such a switch doesn’t require intelligence. It too can be the result of a random process. No analysis by the organism required. Think of it this way: Let’s assume that in order to be “well adapted” to Environment 1, the organism needs to have genes a particular chemical pathway that first produces chemical A, then modifies it into chemical B, then modifies it into chemical C. C is the important product that makes the organism adapted to Env 1. Unfortunately, C is maladaptive in Env 2.
So, you’ve got a bunch of organisms that have genes that produce A, modify it into B, then modify that into C. We’ll call those three genetic sequences Ga, Gb, and Gc. Who knows if that’s the best way to get to chemical C, or even if C is the best way to be adapted to Env 1, but that’s how they currently are.
Now you move them to Env 2. They are no longer thriving, but they’re surviving. Some mutations occur. One of them, by chance, happens to screw up Ga. It’s no longer producing chemical A. All of a sudden, the entire set of Ga, Gb, and Gc are no longer doing anything. I mean, Gb would be happily converting chemical A to chemical B, but there’s no A around. So it is effectively switched off. That organism and its descendants are no longer stuck producing a maladaptive chemical, and they thrive, quickly taking over Env 2.
If you later put the descendants of that mutated organism back into Env 1, they might adapt very quickly. Because, while it took a long process of slow random mutations and selections to originally evolve the Ga, Gb, Gc sequence, it’s still lying dormant in their DNA, and it’ll take only a single mutation to turn it back on.
None of this requires the organism being at all intelligent. It only requires that information is accumulated in the organism’s genetic code.
I don’t think I agree with that (though I don’t know the answer). My impression is that the worse the mutation (in the maladaptive sense), the quicker it is to be weeded out. If something really critical goes wrong, the potential new organism is going to fail fast and hard. It’s the very slight changes that are going to take lots of generations to show. A mutation that makes your skin darker is, over time, going to help your ancestors not die from skin cancer quite so much. A mutation that makes your hemoglobin produced incorrectly so that it doesn’t bind to oxygen properly isn’t even going to make it through gestation.
I’m not saying it’s impossible, I’m saying that it doesn’t appear to exist on our planet, and the stumbling block is that in order for a problem-solving procedure to have a good chance of getting it right first time, there needs to be analysis of problem and consideration of solutions.
Massive trial and error is another approach to problem solving that works - and is the mechanism by which evolution works.
If mutation is directed, what, other than something which can functionally be described as ‘intelligent’, could be directing it.
The solution to any given problem cannot be ‘obvious’ to the genetic machinery of an organism.
A short-necked giraffe is hungry, because its taller peers are outcompeting it for leaves on the tall trees - how can its genome know that the solution to its hunger is to increase the length of the neck?
There’s actually a simpler way to look at this - let’s stick with the giraffe example (whilst acknowledging it to be a bit of a caricature)…
Short-necked giraffe is hungry, how useful is it to this animal even if it does (somehow) analyse the problem, (somehow) conclude that the solution is to produce longer-necked offspring and (somehow) modify its own germline genes to predispose its offspring to have longer necks. How does that help?
The other giraffes that have longer necks have already solved the problem, and are consuming the resources necessary to promote their own reproductive success.
Let’s look at your simple case. Say the short necked giraffe in previous generations had learned to mutate (turn on a particular switch) in response to temperature increase. Does it avoid doing this mutation knowing it may not be useful in this case ? Or does it still keep trying all random mutations ?
What in previous generations it had learnt that “mutating” a certain way leads to size increase. Does it try it ?
How can it had “learnt” anything? There is no known mechanism for such learning, no evidence that any such learning ever took place, and not even a theory for how it might occur.
You can replace everything you say with magic. If you can do that you don’t have science. You need to demonstrate how your scenario is minimally compatible with science first before you wave your arms and say that giant effects have happened.
No. It’s too busy dying.
Here’s how it may have learnt - see this post :
[QUOTE=iamthewalrus(:3=]
Instead of re-evolving the whole sequence, the switch could simply mutate to on,
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[QUOTE=Mangetout]
No. It’s too busy dying.
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On the contrary, any organism when stressed produces more than the usual mutations in their progeny. Please read though the posts.
[QUOTE=Mangetout]
You can replace everything you say with magic.
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Based on the several posts about creationism, intelligent design, magic etc., I am feeling like this question has been a subject of reverse bias. At no point have I mentioned any subscription to any beliefs of mine. I am a strong supporter of science and an engineer by profession.
Scientific theories get modified / adapted all the time when new data comes up or a particular aspect of the theory cannot be explained. It is in this spirit that I am asking this question - the goal here is not to prove the evolution theory is wrong - quite the contrary. The goal is the establish if random mutations are necessary for evolution to work and if it is actually observed.
No, that post says nothing of the kind. Read the full context. I have bolded significant sections.
Directed mutations are not explained in the way you have stated. iamthewalrus(:3 went out of his way to refute that.
If what you are saying is equivalent to Creationism, then you are advocating a Creationist explanation. We are explaining that Creationism is wrong for exactly the same reasons you are wrong. I do not have to make any statements about your beliefs when I find your words making the case for me.
They are and they are. There has been no disagreement on this other than what you have written.
Demonstrably false. The changes induced by selective breeding are a good counter-example.
[QUOTE=iamthewalrus(:3=]
One way that the adaptation would become more rapid is that the genetic sequence for some adaptation is still present in the organism, but is turned off by a simple genetic switch.
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Please read this. This clearly suggests that the organism is not trying things at random but is choosing to try something it had learnt in the past.
[QUOTE=Mangetout ]
No. It’s too busy dying.
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Okay - but is there any evidence to show that the only strategy it follows is to produce random mutations ? Is there evidence that it does not favor previously learnt mutations (or turns on/off a particular adaptation) for size or suppresses previously learnt adaptations for higher temperatures.
[QUOTE= Exapno Mapcase]
Directed mutations are not explained in the way you have stated.
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I am not trying to prove directed mutations. I am really asking is whether mutations are really random - you know has anyone ever performed a randomness test ? And it looks like there is no data anywhere to answer this question.
I haven’t been following this thread carefully, because I have other sites I go to when I feel like banging my head against a brick wall, but I noticed this, and it’s absolutely not true. Mutation rate is, except in a few exceptions, constant regardless of stress level. Unless, of course, the stress consists of exposure to mutagens.
This is also incorrect. You’re confusing mutation with selection. Selective breeding cannot induce specific, desired mutations. It can only select them when they arise. The original mutations are still being produced at random. Note that this is exactly equivalent to what’s happening in natural selection, except that in selective breeding, we can select very strongly for or against specific traits.
I read the posts about mutation rate and was curious, so I googled. Here’s an interesting little tidbit about it:
“A key property shared by all of the underlying models is the assumption that the mutation rate is constant, although it has long been recognized that mutation rates vary between and even within taxa [1,12]. However, there is intriguing evidence not only that the mutation rate is variable within groups but that the variation in mutation rate is correlated with fitness, such that low-fitness individuals have higher mutation rates.”
I just read a little further and found this about stress:
“However, in a very poor environment, death is certain in the absence of a beneficial mutation that confers high fitness in that environment. Individuals with high mutation rates are more likely to “find” that beneficial mutation. Thus, natural selection will favor inducible mutation rates, which are low under normal conditions but greatly increased under stressful (i.e., low-fitness) conditions. Adaptive mutation remains controversial, but there is evidence from E. coli that the stress-induced mutation rate differs consistently with certain ecological circumstances [15].”
Not at all. A mutation is a change, that’s all. Selective breeding demonstrably changes a creature.
No, it doesn’t.
All it says is that if a random mutation happens to “flick a genetic switch” re-activating an existing sequence that had formerly been useful but later had become “turned off”, the resulting adaptation will be faster than re-evolving the whole sequence from scratch.
That doesn’t suggest that the organism is in any way aware that it has this inactive genetic sequence available to it or that it’s deliberately trying to flick any genetic switches to re-activate the sequence. Merely that if the organism does happen to re-activate that sequence by a random genetic mutation, the adaptation process will be quicker.
Speaking as someone four years into a Biology PhD, no biologist working today would agree with you. A mutation is a change to the DNA sequence of the organism. Those are absolutely random. This being the entire point of the question, it’s best to be clear.
Selective breeding relies on randomly generated mutations, and then selects which phenotypes will be allowed to create the next generation. Hence the name “selection”.
You want evidence that something doesn’t happen?
The thing you’re proposing has the same kind of logic to it as the herbalists Doctrine Of Signatures.
Why would any kind of condition happen to provoke a set of mutations that happen to be beneficial in coping with that condition?
The information about what an organism needs to do, genetically, to be able to resist (for example) heat, is not contained in heat. There isn’t a mechanism to recognise and grasp a solution, and there isn’t a solution to be grasped.