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Superfluous genes

  1. Jan 12, 2006 #1
    May one add to Darwin's theory the possibility that we do not use most of our genes to adapt at every generation, but may pass down a large proportion of "superfluous genes," acting towards statistical survival for our progeny, even into the distant future, but not expressed in the environment until then?

    For instance, imagine a trait such as the ability to think in four dimensions. This unused trait may have been passed down from the onset of Homo Sapiens Sapiens. Its application was fulfilled only in the 20th century, when a decendent realized the study of spacetime, helping them adapt to apply science.

    Can you believe that the majority of genes are not used for the immediate survival and likewise adaptation of the individual, but mostly for the probabilistic welfare of future generations? This genetic majority is obsolete as current genotype, but does provide enough probability of vitality to benefit potentially many hundreds of generations to be. Is it the body of an entire lineage that determines whether each link benefits from this virtual chain of ancestral DNA?
     
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  3. Jan 13, 2006 #2
    If I understood you correctly, I don’t agree completely with you.

    That kind of approach is definitely way how bacteria use many of their genes and genome. They have a bunch of stuff and tools they carry with them in genome, just like a Suisse army knife, and they don’t use all those tools/genes all the time, but they are prepared for many different situations.

    But at higher animals and men, there is no such direct correlation between one gene and one specific function. We are 99.8% identical with chimps, and they aren’t thinking about 4-dimensional space time. We got this great complexity standing between our gene and its product, complex regulatory machinery, complex combining machinery, complex gene interactions…
    Example, let’s take FOXP2 gene, responsible for our speech, chimps can’t speek. But hey chimps have that FOXP2 gene why don;t they speek? They have different pattern of FOXP2 expression... sad for them, or maybe lucky :)
     
  4. Jan 13, 2006 #3

    Monique

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    I don't know what you mean by "probability of vitality to benefit potentially many hunderds of generations to be". It sounds like an argument as "someone put those genes in us so that 10 generations from now we can benefit from it".

    I can tell you that there are redundant genes, with overlapping functions, and genes that only get expressed in certain situations, like during a response to a fungal infection. Such genes must be used from time to time, otherwise they'll mutate and lose their function (they wouldn't be conserved).
     
  5. Jan 14, 2006 #4
    I'm not sure if I agree. A gene that doesn't contribute immediately to our phenotype in a positive way has a much lesser chance of being "selected" for future generations (conversely, it has a better chance than one that contributes negatively).
    A genetic mutation would be much more likely...
     
  6. Jan 15, 2006 #5

    selfAdjoint

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    Things are not actually that tight. Look up Neutral evolution, the accumulation of small random changes that are not subject to selection for one reason or another. It happens.
     
  7. Jan 15, 2006 #6

    Monique

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    But if the mutation affects the gene is a deleterious matter, it won't be selected agains if the gene is not active and so it will be lost faster than a gene that is essential.

    You can look at homology between species and find genes that have an extraordinary level of conservation, while others have not been conserved. Using this homology between species you can also find out what parts of the gene are essential for its function and what parts just act as a filler.
     
  8. Jan 15, 2006 #7
    I agree, but we must understand that these so called superfluous genes are there for a reason. Nature abhors a vacuum. Exons, introns whatever you want to call them, they're there to provide DNA with the ability to find novel solutions to evolutionary "surprises". Junk DNA: no such thing IMHO. otherwise why is it there? And we also share 50% of our DNA with a tomato: it's not the similarities that matter it's the differences.
    We evolved speech by standing up, controversial but probably true; you get an opposable thumb you make more complex tools, with more complex tools you can hunt a wider variety of animals, but only if you have the ability to comunicate new ideas, so you use this dexterity to invent gestural language more complex than a Chimpanzee is capapble of this leads to using sounds if someone can't see you, eventually you need more complex sounds and of course your varied diet encourages greater slection of abilities that lead to this, essentialy the diet increases brain power by being mutually beneficial) you eat more fish and mamoths you have more fats and protein to develope brain power, you then have an ability to use this experience to further your skills, this eventually leads to complex sounds, and your cave paintings become more rich and detailed, showing more complex behavioural patterns, this leads to even more complex behavioural patterns which leads to language becoming evolutionary wise more viable. We now have the ability to pass on knowledge much more efficiently than before and so language is selectively beneficial, eventually we develope sounds and vowels, this leads to writing to convey meaning, or symbols which inevitably leads to more expression of ideas, which inevitably makes language beneficial; we now understand much more than we would otherwise if we relied on simple behavioural examples. this leads to a proper symbolic system and speech system, which inevitably leads to language and writing beyond pictoral symbology. This leads to an ability to pass on information, and thus extends our lives beyond simply the ability to hunt and kill. Now age has a significant ability to pass on information and is selctively very beneficial, so we live longer.
    Soon someone finds a way by trial and error of farming, agriculture becomes more prevalent and this is spread by our new language skills, now we need not be nomadic, we can settle and store the food we need for the winter months. And on it goes. all harkens back to that ape that stood up.
    There's a really good reason why we have so much junk DNA, and the answer is self evident.
     
    Last edited: Jan 15, 2006
  9. Jan 16, 2006 #8
    I agree with Schrödinger's Dog. There is no such thing as "junk-DNA", because according to the theory of evolution (which I do agree with, STRONGLY) a species adapts to an environment by mutations over many generations and evolves into the optimal organism for that certain environment. Carrying around a heavy load of DNA which doesn't do anything at all wouldn't be in much favor of Darwin's theory now would it?

    I think that is the same as if a puma would have oak-trees growing out on its back for thousands of generation without any mutations pushing its species towards getting rid of them oak-trees.

    ANYHOW, I don't agree with Loren Booda:

    This "unused DNA" which we have, consisting of transposable elements etc, has definitely a very important function; maybe a space for mutations, maximizing the amount of mutations during recombination etc etc to favour mutations. However, I don't think we have genes stored in this DNA for future use, that would be a bit against the theory of evolution... Because if we had a load of genes which would give us super-abilites (like thinking in higher dimensions), they would have been set to business a long time ago :-)
     
  10. Jan 16, 2006 #9
    Aside: consider the efficiency of either information stored in overlapping genes, or different physical structure dictating different functions from similar sequences of DNA?
     
  11. Jan 17, 2006 #10
    I tend to somewhat agree with Laura Booda for this reason: recently when I read a national geographic it mentioned this interesting quirk chicken farmers encountered. In order to get the most breast meat they continually interbred chickens with the largest breasts, however instead of the population exsisting without variation, repeatedly, chickens they did not want, popped up, regardless of their breding. Therefore, as long as I am interpreting this right, species have the ability to retain variation in their population regardless of breding. This suggests to me further that the DNA contains vast amount of variations, that a species needs to survive or chickens may just be weird.
    -Scott
     
  12. Jan 17, 2006 #11

    Monique

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    That would indicate that a recessive allele resides in the population, when two of those alleles get together (if the allele frequence is low, this won't happen often) you get a different phenotype, although the phenotype of the parents was homogeneous.

    There is a story in the bible about black and white sheep, one guy wanted to have the black sheep, since they were higher in number and agreed to give the other guy all the white sheep. The white sheep bread true and only bred white sheep, whereas the black sheep sometimes produced white sheep and so he had to give them away. I'll look up the source tonight.
     
  13. Jan 17, 2006 #12
    OK humans have evolved quite rapidly in terms of a species the more rapid it's evolution and change in it's behaviour I think the more new genes it has the more new genes the more junk DNA surely and this in turn has lead to more mutation and so it goes on. This junk may of been in our Genes but at some point it had value evolutionary wise and so it payed to increase the amount of Junk DNA?

    Here's an idea? DNA likes to randomly swap genes at some point, wouldn't it sometimes randomly swap with a junk part of the DNA, if it only swapped with the good parts they're likely to lead to configurations that already exist, but by swapping with useless parts it's more likely a novel mutation may occur, 9 times out of 10 the mutation would be useless but or sometimes harmfull which would tend by diversity to quickly end this mutations persistence. If that mutation was of benefit though, it would help with fitness.

    Now if we have more junk does this not increase the pool for random mutation and by incresing help our evolution, this in turn leads to increased evolution which in turn lead to more junk DNA which in turn leads to more mutation which in turn leads to etc etc. Not sure here quite how often junk DNA is used in mutation but it's an idea?

    More likely to be true however was something I read in a magazine that junk DNA helps to preserve genes that are almost hard wired and need very little change making them less suseptable to mutation. I can't remember exactly how this was the case, I'll have to fish the article out from somewhere?
     
    Last edited: Jan 17, 2006
  14. Jan 17, 2006 #13
    National Geographic would not have mentioned it if it was not significant. Besides I do not think you understood me. I know that populations have dominate and recessive genes, but the chicken farmers stated that according to the current theory dealing with dominate and recessive genes, "We should have run out of variation by now." I am not sure of the details but they were suggesting that there was some mechanism within the chickens DNA that could produce variation besides the strait forward dominate and recessive genes.
    -Scott
     
  15. Jan 17, 2006 #14

    Monique

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    I didn't see the National Geographic story so I'm not sure what happened there. Maybe there was a strong in-utero selection for embryos without the particular mutation, the chicken would have to be less fertile for this hypothesis to hold up. Btw, the story I mentioned is Genesis chapter 30 where Jacob agreed to tend the flock of his father in law Laban and as payment was allowed to keep the speckled and spotted for himself (who says there's no genetics in the bible :wink:).
     
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