Have we stopped evolving.

Discussion in 'Biology & Genetics' started by Halo, Oct 15, 2002.

  1. Voodoo Child Registered Senior Member

    No, your highly deceptive, out-of-context quote actually deals with what Darwin thought was a potential problem, if you read the full quote you will see that he finds this is not an insurpassable problem.

    ad hominem

    Circular how?

    You misunderstand the dolphin odor reception thing. Dolphins have no need to detect volatile odors. Why would God put redundant DNA of this nature in dolphins? Why is it encoded in practically the same way as in some land mammals? This is not similarity of function, redundant means it doesn't function.

    Really, this discussion would better belong in pseudoscience or religion.
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  3. scilosopher Registered Senior Member

    Glad to hear I'm an appreciated contributor. I must say that although evolution is mentioned frequently in classes and seminars I attend, I am amazed at the lack of explicit treatment and discussion of evolutionary theory in my program (maybe it's presupposed - but I was a bioengineer undergrad). Seeing as I've never actually taken a class on evolution I would be interested if you could refer me to a good text for overview and introduction to the topic appropriate to one that has a fair degree of tangential knowledge and general familiarity.

    It's good to see a discussion with some interesting meat, in addition to being busy (PhD program) I had stopped visiting so much because the clutter seemed to often threaten to overwhelm most topics.

    I'm a big fan of integrative efforts of various biological disciplines as well as insights from other scientific backgrounds (my point being I think an evolutionary approach is important to understanding the way developmental systems are organized). It seems unfortunate that the excitement of the potential to apply biological knowledge to medicine has de-emphasized questions of evolution in much of the molecular biology research done (although insight into the evolutionary process would aid in portability of knowledge between organisms). Though it was also typically very one molecule oriented, which removes the necessary context required to actually consider the evolutionary potential of a gene.

    Anyways, enough personal clutter ... morphological blockage of reproduction - I certainly didn't mean to suggest it wouldn't happen. I think biological systems are such that any mechanism that would do something would occur at some frequency, but there are biases given the details. The chirality swap is an interesting one - I was thinking too symmetrically - my presupposition of morphological mechanisms being uncommon was borne on the idea that most morphological changes that would disallow the physical act of mating would typically not improve fitness and would be blocked for that reason.

    In the spider example not knowing what exactly those structures are makes any hand waving thoughts on their genetic/developmental basis difficult. I guess though, that in any creature that has complicated specialized mating structures the potential of morphological blockage is also greatly potentiated. I was thinking more of the typical rod and hole arrangement ...

    As to saltation and graduation - I'm not clear on the exact definitions, but would imagine graduation is a gradual change and would therefore guess saltation is a radical jump. So here I think it really depends on the trait to be discussed and the molecular mechanisms involved. Something like the length of a limb could be changed by the increased diffusion of a morphogen (diffusing signalling molecule controlling cell differentiation and programming) leading to an increased limb length. When it comes to generating shapes the situation is obviously more complicated and one would suppose that there can be more radical shifts. I guess my point would be the division may be an arbitrary one differentiating two possibilities given the characteristics of molecular mechanisms shaping the morphology.

    The hox genes are also relevant here. In Drosophila one can convert the haltere (which is a derivative wing like structure used in balance during flight) to a wing by knocking out Ubx a hox gene (which are all transcription factors). This leads into Carroll's main argument regarding morphogenetic evolution and hox genes - apparently there is a tendency for repeated body structures like centipedes to give rise to organisms with fewer segments that are more differentiated. It is interesting that the event comes from the differentiation of duplicated structures similar to the genetic situation of duplicated genes become differentiated in function.

    Indeed there seems to be some type of scale invariance. It happens with organisms (speciation), segments, probably cell types, genes, and sets of genes (Hox clusters are actually duplicated - there are 2 in Drosophila and more in human and mouse though I don't remember how many). All of evolution seems to hinge on copying with mistakes (edit: I should probably say changes as evolution certainly takes advantage of this so it's encorporated and the religious might attack the word usage). It's interesting to note that without fluctuations/temperature/"randomness" there would be no evolution.

    Anyways enough pontificating - some hox references (yanked from the suggested readings in Carroll's book):

    Duboule D, Dolle P.
    The structural and functional organization of the murine HOX gene family resembles that of Drosophila homeotic genes.
    EMBO J. 1989 May;8(5):1497-505.

    Krumlauf R.
    Hox genes in vertebrate development.
    Cell. 1994 Jul 29;78(2):191-201.

    Graham A, Papalopulu N, Krumlauf R.
    The murine and Drosophila homeobox gene complexes have common features of organization and expression.
    Cell. 1989 May 5;57(3):367-78.

    enjoy ... I haven't read them myself, but they looked like the best to start with (despite the need to dig up the hard copy).
    Last edited: Dec 15, 2002
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  5. spuriousmonkey Banned Banned

    development and evolution

    first of all...i would have to remark that developmental biology has mainly focused its attention on developmental biology (how surprising) and not so much evolution. I think that it is just now becoming fashionable to approach developmental biology from the evolutionary perspective. However, the process of speciation is quite a specific problem and i can't really remember ever seeing a specific paper about a developmental study on this problem.

    What is studied, however, is the gradual and non-gradual changes of structures. One of the more interesting papers (because it is in my field) shows a simple computer model of inhibitors and activators that can produce different tooth shapes (teeth are interesting, because they have such a good fossil record). In this particular paper, they show the actual morphology of the molars of the mouse and vole (a closely related rodent) and the morphology generated by the computer model. That's not it of course. If you look at the distribution of actual known inhibitors and activators then this pattern also corresponds to the one generated by the computer model. Another interesting feature is that the distribution pattern of inhibitors and activators actually preceeds the morphology (with hindsight somewhat logical).
    By changing the parameters of the model you can create different tooth types...and their intermediates (such as fossil teeth of extinct species). I also know that the model can predict quite drastic changes (for when instance a gene is knocked out).

    therefore i think you can have both...gradual and quite huge changes in the development of structures/organs caused by both gradual and major changes in the genetic code. We might then speculate that something similar is the case for developmental speciation events. A structure that is important for defining a species might change gradual or quite radical.

    I have given the yeast reference in an earlier post and there the speciation event is radical. Offspring cannot reproduce (or with great difficulty) with the parent species.

    the other reference is:

    Salazar-Ciudad, I. & Jernvall, J. (2002) A gene network model accounting for development and evolution of mammalian teeth. Proceedings of the National Academy of Sciences, U.S.A. 99: 8116-8120
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  7. paulsamuel Registered Senior Member

    reply to scilosopher and spuriousmonkey

    thanks for your replies;

    i am excited about continuing our discussion re: evolution and development.

    I thank you both for the refs. and I will get to them. However, I am off for a christmas vacation and won't have internet access 'till I get back on 1/8/02. Please don't think I am blowing off the discussion, because I am very interested in continuing it.

    I personally am only familiar with Futuyma's text "Evolution." But I am quite happy with it as a reference tool (I wouldn't recommend reading it outright, although I have found myself reading on and on without knowing it). In regards to medicine and evolution, there is a book called "Why we get sick" which is written by an evolutionary biologist (who decided to get an MD) and a full time MD. I highly reccommend the read, it's written for an educated lay person, it's extremely interesting (a fun read), and it's quick (one could finish it in a couple afternoons).

    Currently I am thouroughly enjoying reading Mayr's "The Growth of Biological Thought" which I highly reccommend, mainly because it incorporates my three passions, history, philosophy and biology. I can't remember learning so much from a single book.

    Well, good luck in your studies. Have happy holidays and a happy new year. I'll get back in 2003.

    Best, Paul
  8. spuriousmonkey Banned Banned

    general book recommendations for xmas

    this is slightly of topic i guess, but i blame paulsamuel for it all...here are my humble recommendations for xmas...

    i could also recommend Ernst Mayr's 'the growth of biological though.' I have it on my bookshelf and usually use it to look up things. But it is a bit longish and personally i could never be bothered to read it in its entirety.

    if people are really looking to put something scholastic on their book shelf you might also have a look at 'ontogeny and phylogeny', by Stephen Jay Gould. But once again, i never bothered to read it totally.

    for the non-believers in evolution i would recommend the aging 'Darwin's dangerous idea', by daniel c Dennet. Maybe then you will find out why you are so scared of evolution. This one is quite readable.

    but if you really want to read something interesting then why not give 'on the origin of species', by Charles Darwin a go. It is one of the most readable scientific books ever, and especially of this era. It is still a good read today. and definately the best book of all mentioned.

    personally i am not going to read anything scientific with xmas...I need a break.
  9. scilosopher Registered Senior Member

    Spurious Monkey - that PNAS paper looks interesting, I'll have to check it out. Glad to have someone else w/developmental expertise and interests on the site. I'll probably mix in some science reading myself, just no papers and stringent writing quality standards.

    Paulsamuel (and everyone else) - happy holidays! No worries about going incommunicado, I personally will not be very web accessible over break myself.
  10. Bienke Registered Member

    I have been woundering for a long time in actual fact we have stopped evolving. we used to race towards things like being the first to break the sound barrier the first into space the first to the moon and we did it. now i am seeing us just stand still for a very long time we have the tec and know how to do so much i just cant for the life of me understand why we cant move forward with more exploration of the unkown out there
  11. John99 Banned Banned

    But the problem is that evolution does not require nay input\interaction from the subject beyond compliance.

    Then we are confronted with the inevitable possibility...devolution or deterioration of species. I dont think we ever evolved to begin with so devolution does not concern me. Except when stupid people reproduce at alarmming rates then it could be a rweal problem//

    I am gouing to post a scenario dealing with this in the human science section, it is going to be good.
    Last edited: May 1, 2007
  12. McMicky Registered Member

    If it truly is in our genetics that we should have 6 fingers then the persons children would also have 6 fingers this would mean that there is a need for 6 fingers, cutting a finger off does not change genetics. The persons 6th finger could quite easily be a mutation.
  13. EmptyForceOfChi Banned Banned

    i would say we are getting less hairy, we are still adapting to climates, we tan and get lighter due to our enviroment, and we are getting respectively smarter,

    i would say no we are still evolving quite well, i dont like to seperate the word evolving from the term adapting. because thats all evolution really is, "adaptation to current situation"

  14. Oniw17 ascetic, sage, diogenes, bum? Valued Senior Member

    There aren't many isolated populations anymore. I think that means that we're evolving more slowly.
  15. S.A.M. uniquely dreadful Valued Senior Member

    Or not quite in the right direction.

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  16. EmptyForceOfChi Banned Banned

  17. psikeyhackr Live Long and Suffer Valued Senior Member

    Television, psychologists and now computers are being used to promote devolution.

    Knowledge is something for people to play power games with to manipulate others. The schools make the acquisition of knowledge difficult and expensive. All they need to do is create a collection of good books. They would all fit on one DVD. How expensive is it to manufacture DVDs these days.

    People don't want to make proper use of the technology.

    Teach Yourself Electricity and Electronics by Stan Gibilisco
    The Art of Electronics by Horowitz & Hill


  18. Oniw17 ascetic, sage, diogenes, bum? Valued Senior Member

    How are psychologists promoting devolution anymore than AC and global transportation(or at all?)?
  19. Ophiolite Valued Senior Member

    I appreciate that this post was made some time ago and that others have likely responded, but I could not let this malodorous staement go unremarked.

    I have little idea, and even less interest, as to where you obtained your education, but in the matter of historical geology it is so badly flawed as to be 180 proof nonsense.

    Historical geology was based upon the so called Law of Superposition, which notes that generally older rocks lie beneath younger ones. We might credit Steno with the first observations in this regard. Then it was noted that the same rock units tended to contain the same fossils. William Smith springs to mind in this regard. Then and only then was it observed that there appeared a progression of forms within these rock units that matched the age sequence revealed by application of the Law of Superposition.

    Therefore, thoughts of evolution followed inexorably from early efforts in historical geology. The only circular reasoning apparent here is the little voice running around your skull spitting vile calumnies.

    Individuals with such a disregard for the facts, when such disregard is willfull as I believe it to be with you, are guilty of mortal sin. I can forgive you, I am less certain the Creator will.

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