lordcheesehorn

Delta 1212, thank you! Why? Could there not be a slight influence from the environment, a weak magnetic pull, or ‘a very small difference in initial starting conditions leading to a drastically different outcome’, if you will? Could you explain how biologists can be sure that their models match what we see? Let’s say it took x years for a wasp to evolve an extremely complex set of venoms and behaviours required to stun a caterpillar and bury it for its eggs to feed on. How can biologists be sure that it only requires random, survival-selected incremental mutations to get from one behaviour to another in x? Are you sure that there is no proposed mechanism for cells [responding to the environment] and influencing genes? I’m sure I’ve read in a couple of places that this might be possible – I forget where now [and will investigate forthwith]. Nevertheless, surely it is theoretically possible that a hitherto undiscovered mechanism in the cell might be able to influence (again, influence, not flat out write) genetic code? No, I’m not. I’m asking whether the speed, direction and handling of the car might not necessarily be entirely down to what’s in the engine. Another question, if you have a moment. Bit off topic: but how do developing cells know what to become? I’ve read that biologists do not yet know how a cell in a foetus knows to turn into, say, a nerve cell in the thigh, develop precisely all the architecture required to do its job and set up shop in just the right place… that this info cannot possibly stored in the genes. Any thoughts?

Overtone: thank you for your long answer. Line one. Chaos theory, as far as I understand it, often describes systems comprised of many individual elements which seem to be behaving randomly, and yet, as a whole, or viewed from a different perspective, exhibit some kind of order. Can you explain how you have ruled out any kind of order in mutating genes or any kind of environmental influence? Line two. I am intrigued about ‘recent genetic engineering advances [that have] provided us with the first known instances [of “successful” genetic change]’. Can you elaborate? Also, you say you ‘have observed none of the predicted patterns specific to environmentally guided genetic alteration.’ Is not the outstanding appropriateness of just about every organism to its environment a sufficiently compelling reason to assume that the environment has some impact on genetic evolution? From what you say, I gather that we have not ruled out some means for the environment to influence mutations. I am not suggesting that there are no such things as random mutations. What I am endeavouring to understand is if the environment might have some means of influencing genes, or if cells might have some means of genetically responding to the environment. I gather that science has not found such a mechanism, but I am also starting to think it has definitely not ruled out that it might be there. All further thoughts welcome.

One arguing that the environment influenced mutations would surely point to the extraordinary aptness of just about every living creature on earth for its particular situation.

Thank you. I understand this, but can you (or anyone) tell me what evidence there is that successful adaptations in the wild are due to random mutations and not through some mechanism (genetic or otherwise) that responds to the environment?

So... Can anyone help? I now understand how we might be able to rule out successful adaptations in the lab being caused by survival-selected random mutations, but how have we ruled this out in the wild? What evidence is there that successful adaptations in the wild are due to random mutations and not through some mechanism (genetic or otherwise) that responds to the environment?

Sorry to repost this – just that I didn’t get an answer to my final question in this thread. Mostly, I think, because the question changed and because of my imprecise (or, at best, non technical) use of the world epigenetic. I now understand how we might be able to rule out successful adaptations in the lab being caused by survival-selected random mutations, but how have we ruled this out in the wild? What evidence is there that successful adaptations in the wild are due to random mutations and not through some mechanism (genetic or otherwise) that responds to the environment? Many thanks for your time.

Thank you for this clarification. Kind of clarification, its a bit misty to me... what would you suggest as a pithy dictionary definition? Inheritance through either meiosis or mitosis (as opposed to what...?)? The dictionary in question is the Oxford Shorter. Before you despair, words are famous for having multiple definitions. Could you explain why your definition is incompatible with the simpleton’s version? And finally, you seem to know what you are on about, if you could find time to read through the thread, I’d love your view on the question I am (or have ended up) asking.

My understanding was ‘resulting from external rather than genetic influences’ – that’s what the dictionary says, and that’s how I have always understood it. Not being a professional Biologist I am not surprised to find that my understanding is imperfect. If you are able to enlighten me as to my misuse of the term above (without, if possible, condescension), I would be most grateful. I am seeking strong evidence that successful mutations in the wild are not influenced by the environment.

My mistake then. I thought it meant ‘non-genetic’ – meaning from the organism, the environment, martians, anything not the gene. What does it mean then? How do we know this? If its through lab-study, then perhaps the environment (a lab, rather than the vivid and complex wild) will not be having a positive influence? And how do we know that even with most mutations being either neutral or slightly deleterious in their effects the environment or the organism isn’t influencing the creation of the non-deletarious ones? Is this not what we find? In actual life, rather than in the lab? How have we ruled out that successful mutations in the wild aren’t influenced by the environment? Thank you for your time. I’ll be back tomorrow. Hope you chaps are still here.

I see... but I still can’t see how any of this rules out the hypothesis (or even significantly affects its unlikelihood) that the environment / context / phenotype is pushing (albeit gently) gene-mutation in one direction rather than another. How? How can we be sure, or sure enough? A lot seems to ride on this, for me at least. (Many thanks again for your time. Late here. Have to go to bed now. Will pick this up later and hope you stick around for a day or three. This matter very important for me.)

I see - I think.... So its something like this: the bacteria are artificially mutated. Let’s say there are ten bacteria and ten possible mutations a bacteria can have (I suppose there are millions, but for the sake of argument) and each bacteria has one of the ten. They are then placed in an environment which selects for the survival of one of the mutations (lets call it mutation x). The one that has that mutation x survives and the others die. Is that it? Or something like it? If it is, I understand what you are saying, but I don’t see how this experiment rules out Lamarckian-influenced mutations in the wild... In the wild organisms do not always (or even ever?) move from one situation to a completely different situation with a set of genes to tackle the new situation, but exist in a changing context that they must change to adapt to. What rules out the hypothesis that, for example, a horse’s efforts to eat from taller and taller trees influences its gene mutations towards long-neck varieties? I have another, far crazier hypothesis, but I’ll leave it here for now. Many thanks for your time on this. One other thing, what do you think of this?

Thanks... but either a) I don’t understand your answer or b) I didn’t phrase my question properly. I fear a)... What proves that it is random mutations that select for survival rather than the influence of the context / environment / phenotype / organism or anything else? Seems to me that in the case of the experiment you mention there is no proof that, in the wild, such bacteria couldn’t mutate towards survival-friendlier states under the pressure of a changing situation? What proves that eyes evolved entirely through random mutations and not through some mechanism whereby the gene responds to the environment somehow?

Hello. I would like to know what solid evidence there is that successful genetic modifications are caused by random survivial-selected mutations and not through the epigenetic influence of the organism or the environment. Many thanks for your time.