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Is information added to genome by evolution?

  1. Apr 6, 2010 #1
    Hello is is a continuation of a discussion that got started in the special relativity section but is a split-off and more appropriate here.

    The question is does evolution add information to the genome?
  2. jcsd
  3. Apr 6, 2010 #2
    The question this has brought to my mind is "what is information"? Entropy I have a better idea about. I would say random mutation does not add information it is just a random toss of the dice and the result has no particular meaning. It is only after natural selection that some random changes are "found" to increase reproductive success and other random changes are "found" to decrease reproductive success. So is there in fact any information added by the random changes. It seems in fact that entropy increases. It seems to me that it is the selection process that narrows the combinations down and "raises" the information content????
  4. Apr 6, 2010 #3
    I'm a bit rusty on Shannon information (the mathematical theory of communication), but wouldn't it say that all mutations (as noise) increase the quantity of information in the gene pool, while (natural) selection decreases entropy (as well as information)?
  5. Apr 6, 2010 #4
    I think we need two ideas gross information versus useful information. I do see that a message with noise injected takes more bits to encode but I do not see that it has more useful information. for example

    "hello there, I am fine" versus "helhdlo twhere ,c Ip am fine"

    and in the case of DNA long sections of repeats aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa that in fact code for nothing (at least that we know of).

    I guess information is just a measure of complexity how many bits does it take to transmit and does not tell us anything about is it interesting.
    Last edited: Apr 6, 2010
  6. Apr 6, 2010 #5
    The question is made more complex by the fact that we're not just one organism really, but a collection of cells. Our DNA allows ancient viral (and who knows what other) DNA/RNA/mRNA to survive. That doesn't benefit US, but from an evolutionary standpoint, WOW, those genes won.
  7. Apr 6, 2010 #6


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  8. Apr 7, 2010 #7
    Making allowances for the use of the term “evolution” where “selection” or adaptation would be more precise, yes, it can add information, and commonly does. (There are tricky, though important, classes of cases where a parasite or a creature adapted to a very convenient environment might *lose* part of its genome through adaptation, but ignore them for now.)

    But don’t forget that you can get a lot of informational negentropy from a small amount of usable thermodynamic energy. The information is of the order of the log of the thermodynamic energy. The main function of your screen from that point of view is not the energy you receive, but the heating of the room, even if you use a cool screen technology like LCD. So the amount of evolutionary information you can gain from selective effects of thermodynamic processes is *large*!

    And thermodynamic negentropy, as you know, comes cheap as long as you remember that you pay more for what you use, than what you get out of it.

    But the nature and behaviour of information from various points of view is very, very confusing. Remember that physically speaking noise is also information; information that one does not want. If you are trying to find out what someone is saying, the most glorious music is the purest noise. To an insect or bird on a windswept island, genes for flight can be (genetic) noise of the worst kind, which is why selection produces so many flightless species in islands of various kinds.

    Consider a lump of bitumen in a container. If you want it to fit the container, the task of carving it would be demanding and require a high input of information as well as energy. However, if you just leave the lump to settle in its own time, it will fit far better than you could carve it. That is information creation of sorts; it derives the necessary negentropy from the thermodynamic negentropy available from the potential energy of the height of the centre of mass of the bitumen above the floor of the container.

    Similarly organisms get the energy needed for the creation of more genetic information from their food, sunlight, and whatever else might be available in the environment. Those that fail contribute their resources to other organisms, luckier or better adapted.

    That is just a sliver of the picture, but I hope it helps.

  9. Apr 7, 2010 #8


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    Selection would reduce information. Reproduction increases the variety and then selection removes it. The two would in general be in an equilibrium balance, keeping a genome continuously adapted to its world.

    (BTW, random mutation does count as information. Meaning is something else. Although you could say that the information that is preserved via selection indeed proves itself meaningful of course.)

    Creationists incorrectly use the fact that selection reduces variety as an argument to say that novelty cannot evolve.
  10. Apr 7, 2010 #9
    There is merit to this remark, but it generalises too freely about reducing information. I should like to emphasize that it is quite possible for a new genotype, successful under selection, to contain more information than an older one. In fact it might contain all the old genotype plus something new.

    This is perfectly true, but the question of selection and adaptation is very inconsistently correlated to the amount of information gained or lost. Consider our mitochondria for example: they have lost part of their genome outright, and relegated part of what they lost to our host DNA! Part of that seems to have been because they are in the unusual situation of largely needing to minimise their footprint. Most cells, especially eukaryota, happily carry a huge top-hamper of DNA.

    Meanwhile other creatures completely dump large chunks of DNA coding for no-longer-wanted functions, although of course more frequently they just leave it lying around until it degrades or loses its meaning. This too can mean physical loss of information content. As you rightly say, there is a distinction between info & meaning. Maybe we could speak of meaning as functional information. Then there has been a loss of functional information.

    <siiigh!!!> Creationists don't seem to be up to either logic or honesty. I suppose that is why they are creationists. They claim to represent the God of Truth, and proceed to do so through error and lies. And they then claim that Darwinism is blasphemy!!!

    In fact of course, selection can entail either loss or gain of info; commonly both at once!


  11. Apr 7, 2010 #10
    Given the emerging understanding of the role of mRNA, I'm not sure we can still safely assume what genomes are "useless" and which are used. Rather, it's a matter of relative persistance, and as we interact with the environment, possible expression.

    I get the idea that some believe you can look at genomes and it reads like a book. Jon you make excellent points, akin to telling someone that they're trying to apply Euler equations to viscid flow.

    DAMN this topic is just so frusterating, especially given what Texas is doing to the textbooks so many will use. I would be doomed without the education I recieved, and now I have a "phew, lucky timing!" feel because I missed the DEGRADATION of science by religion! I could scream, or cry.
  12. Apr 7, 2010 #11
    Hi FD,

    You and a lot of other folks, and not just with RNA! Trying to work out what parts of the cell store and apply information, and in what forms, is like trying to make sense of a population of multiprocessor, multifunction, multi-connection computers with no handbook and little understanding of the operative functions.

    Plus, it is pretty obvious that some of the "junk nucleic acid" really is junk, and that some of the rest has non-obvious functions that are not closely related to any particular structure, much as we might absorb leaked oil in a mechanism either with a wad of cotton waste or wood shavings, whichever is to hand. It does not mean that the absorption is unimportant, nor does it mean that the user's manual mentions it!


    I know the feeling. The best you can do is to make sure that you are informed, that you avoid getting people's backs up, and that you are ready with answers for those willing to listen. Don't worry about those who don't want to listen; you are not doing them any favours by wasting your breath on them. Do lots of reading to make sure you are ready to deal with the curve balls that they develop. Remember that scientists don't carry curve balls (much!) simply because they don't want or need them. If they do need them it is no longer science. The anti-scientists (not only anti-Darwinists) must specialise in curve balls because they have no better weapons, no honesty, no wisdom, no humility, none of the stuff that the bible (or Q'ran, or practically any religious writings) praise.
    Unfortunately, that means that they become curve ball specialists, and hard to deal with.
    Ironically, the non-curve-ballers, the ones that simply put on anti-smiley self-righteous masks are just as hard to handle. "Can't, won't, shan't, don't" deaf-adderism is a powerful weapon.

    Think cheerful thoughts!

  13. Apr 7, 2010 #12
    Well said, and thank you Jon, you've cheered me up. :smile: For the record, if I read any more my eyes would bleed. As it stands, when I'm not reading, I listen to unabridged audiobooks. I had trouble getting to sleep around age 8 ("wait, I'm going to die someday? I CANT SLEEP!" was part of the issue) my grandfather gave me an unabridged audiobook cassette of 'Gorky Park' (I know, I know... lol) and 'Farewell My Lovely'. From there I ended up with a very VERY large number of "Old Time Radio (OTR)" such as The Green Hornet, The Shadow, Sherlock Holmes (the second book I read was a compilation of the comolete SH works... so this was BIG DEAL to a young me), and of course,

    "The Fat Man! "There he goes across the street into the drugstore, steps on the scale, height: 6 feet, weight: 290 pounds, fortune: Danger..." :rofl:

    I then had the fortune to live in Ma, USA and have access to some fantastic libraries and schools. And read... and read...
    and read...
    And then the internet, or more importantly, Mpeg Layer Three...
    did I mention that myself, and a few others set up the "techmasters" (i.e. proto IT student labour) at our highschool?

    Did I mention that we installed modems and such for faculty when they lit up their T1 lines...

    Did I mention that I snagged a drill from the Theatre workshop (where I avoided sports other than swimming and fencing), and we got some cheap network cards and setup a LAN in our dormitory. Hehhehe... Over a year before my HS would be 'wired', my friends and I were having lan parties via the holes drilled under doors and coax.

    Ahhh memories. Sorry, I've gone off on a serious tangent, but this is the first time I've been enjoined to read since I started skipping classes in 3rd grade to sneak books and read in the bathroom for hours! :redface:
  14. Apr 7, 2010 #13


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    You also have to be careful that advanced, evolved, complex doesn't necessarily mean more information.

    Mammals have relatively few genes compared to 'more primitive' (whatever that means) organisms. One reason is that they have a very constant body temperature so generally only need one chemical pathway to manufacture each protein.
    Cold blooded animals and especially amphibians often need a dozen different ways of synthesizing the same molecule depending on body and ambient temperature, environment etc. All these pathways need many more genes to code for the proteins and enzymes required.

    And of course animals that have a larval stage need 2 or 3 complete genomes for different phases of their lives.
  15. Apr 7, 2010 #14
    Whoops! :redface: :redface: :redface: I really didn't mean to come out patronising, FD!!! All I meant was that that was where to acquire your intellectual weapons and prepare to hone them! Sorry about that. You make me feel as though I were tempting an addict with an uncut sample! The fact that I was telling a local where to find the pusher is a mite embarrassing. As a member of a bookish family I can well understand the obsession. And the frustration with folks who think anything of the kind is unnecessary and uncool.

    But thanks for the heads-up! :smile:


    Ahhh memories. Sorry, I've gone off on a serious tangent, but this is the first time I've been enjoined to read since I started skipping classes in 3rd grade to sneak books and read in the bathroom for hours! :redface:[/QUOTE]
  16. Apr 7, 2010 #15
    Not to mention that twins could have different genes expressed due to environmental causes, so detrmining the utlity of a given region is not at all clear, although as Jon said, some is clearly "Junk"

    Of course, there is the question: why does that junk hang around? Did it have a use? COULD it have a use again, should environmental conditions change?

    Then, to emphasize mgb's point, think of the maladaptive/adaptive nature of SCA (Sickle-Cell Anemia). In one context you have an affliction, but don't get the "whole shebang" and you just find yourself resistant to Malaria. Clearly SCA is a mutation, of SSA actually, but it survives because of another unrelated organism. If we eliminate Malaria tommorrow, it wouldn't be junk, it would be archaic.

    Then the question of perspective arises, and the basic notion that whether or not you get expessed or not, if you're a gene hitching a ride on a whole species, you're doing pretty well.

    @Jon Richfield: I didn't take you to be patronizing at all! This is the internet, and we have to communicate to know who we're talking to after all. Telling someone to read is ALWAYS a good idea... then again... I'm biased? :rofl: I was just sharing an anecdote with someone who I thought ( and it seems I was right) would appreciate it.

    Don't worry, I'm no longer stuffing books down my pants and slinking away out of boredom. ;)
  17. Apr 7, 2010 #16
    Hmmm... Interesting point. Thanks.

    Small quibble: as you point out, having multiple active copies of pathways does typically entail extra control and accordingly more info, plus:
    Having duplicate information does entail having extra information. One measure of that extra information is the difference between the data-compressed versions of the "redundant" and "non-redundant" genomes.

    Note that I am not saying that there are compressed versions in nature, only that if one were to compress them, that would show how much information inescapably existed in the genomes in question.

    Also, another quibble: "complete genomes" is something of an overstatement surely? It would be an unusual creature that has no autosomal genes used in both the larval and adult stages. Are you aware of any work to assess the respective volumes of genes required by the different stages? It would be interesting to compare say, the genomes of Thysanura with little metamorphosis, with those of beetles of the family Meloidae with a metamorphosis of : egg, triungulin, grub (a few instars), (sometimes a diapause phase), and imago.

    I realise that there are definite requirements for the control of such complexity. I also realise, but without accepting the opinion, that some workers urge the view that successive stages of metamorphosis represent ancestor species that hybridised to form metamorphosing species. This hypothesis would be consistent with "2 or 3 complete genomes", though I accept that it is not entailed by it.

    Please feel welcome to elaborate,

  18. Apr 7, 2010 #17


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    Different pathways to create the same protein don't necessarily share any gene sequence. Just as a C++ and Java program to serve this site wouldn't necessarily have any bytes in common.

    Yes a bit - but if you have to be an egg, a caterpillar, a pupae and a butterfly you are going to use a lot more genes than a person.
  19. Apr 7, 2010 #18
    Am I the only person who finds the notion of an insect, driven by insticnt to entomb itself and then liquify and reform, really really disturbing? It's nature, and it's beautiful in a way, but the process between "caterpillar" and "butterfly/moth" is :yuck:
  20. Apr 7, 2010 #19
    Creationist Myth Exposed: "Evolution does not add information"

  21. Apr 7, 2010 #20


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    Selection of course cannot reduce information it cannot see. If a top hamper stuffed with junk does not reduce fitness, there is no mechanism operating to remove it.
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