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    Dear Mr. Dollo: You Were Both Right and Wrong
    By Michael Martinez | March 10th 2013 04:23 PM | 5 comments | Print | E-mail | Track Comments
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    Michael Martinez has a Bachelor of Science degree in Computer Science, an Associate of Science degree in Data Processing Technology, and a few certifications...

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    I read with interest the recent disclosure that several biologists suggest they have proven Dollo's Law (that biological evolution is irreversible, a 1-way path through genetic change and time) is at the very least not perfect and perhaps may simply be wrong.

    Never having taken a biology course much less one on evolutionary theory I can't say I know anything much about Dollo's proposition other than that he posed it over 100 years ago and that Richard Dawkins supposedly characterized it more as a statement about probabilities.

    Evolution is one of those fuzzy areas of science where we have collected many facts.  I remember hearing one of my history professors pre-empting near-inevitable religious arguments from his freshman students against evolution by saying simply, "We know that evolution occurs: just look at dogs.  We controlled their evolution."  The same could be said of cattle, horses, and other critters our civilization has grown up with.

    Change in species is a fact.  But does the change really have to limit itself to an everlasting bar against returning to old forms?  I can't believe all biologists really believed this.  Otherwise, why would anyone have attempted to preserve Przewalski's horse?  The population had dwindled to a small number of zoo-kept animals by the late 1950s.  Supposedly, that was too few to ensure genetic diversity, and yet today we simple lay people are told that Przewalski's horse has a pretty good chance at recovering in the wild, even to the point of building up a new genetic diversity that can sustain itself and (I'm being extrapolative here) eventually lead to sub-speciation (assuming the species lasts another 1-10 million years).

    I am reminded of the (super-volcanic) Toba Event (of about 70,000 years ago), in which (supposedly) humanity was nearly wiped out, reduced to a small number (perhaps only a few thousand) of "breeding" individuals.  We appear to have made a remarkable recovery since then (along with -- presumably -- many other species that were similarly threatened).  These kinds of genetic bottlenecks have probably happened quite often throughout Earth's timeline.  In fact, I'm sure they would have been necessary for a lot of speciation events (which, of course, were not real "events" but long periods of genetic isolation).

    But there is no going back, it seems.  As our environment changes we move forward biologically and there is no going back.  Various mass extinction events seem to indicate that even though evolution might swing back to a similar form, function, and lifestyle the actual genes won't return within any specific species.  Of course, gene-level adaptation doesn't mean that old habits cannot be reacquired, as the University of Michigan team argues based on their research.

    Life can adapt in multiple directions and that may indeed include going back full-circle.  Last year I wrote here on Science 2.0 that "Naturality does not return to a prior state, though [a Chronocity Set] S may reassemble itself into something that looks like a prior state (but with different components)".  Although I invoked the theory of evolution in that article to help describe the increasing complexity of the universe (as it changes over time) I was not aware of Dollo's Law.  Now, having read a single article that fails to encapsulate the entire debate, I cannot help but notice a strong similarity to my proposal, that change is essentially unidirectional but that change may nonetheless lead to something that looks and feels (but is not) a reversion.

    If the biologists could find a pre-parasitic ancestor of today's non-parasitic mites, would they be able to establish a 1-to-1 genetic correlation (thus showing that evolution did indeed reverse itself) in the DNA?  If such a comparison could be made, and the result confirmed, then my idealistic comparison is not really valid.  If, however, we could show that the probability of return to a precise biological (genetic) state is zero then that would provide us with a clear example of a Morphing Set in terms of biology.

    Is the genetic code of life a transformational puzzle or a transitional one?  If it is transformational then any organism no matter how complex or simple could evolve to take the precise genetic form of its ancestors.  If it is transitional then no matter how similar an evolved function is to an ancestral state there must be some distinct difference.  I see it as an Either/Or question because in a Transformational Genetic Universe the transformations alone would suffice; however, in a Transitional Genetic Universe life would be forced to find new solutions to old problems.

    My theory of Naturality cannot exist in a Transformational Universe.  And that leads me in my lay capacity to wonder if the Universe is Transformational or Transitional.  As I now understand it (thanks to a paper Hank pointed me to) the space between things is constantly expanding.  The greater the distance between any two things the faster all the space in-between them expands.  In a Transitional Universe that expansion can change but I don't think it can be reverted.  However, in a Transformational Universe that expansion might indeed revert.

    By "revert" I don't mean simple "reverse".  A reversal of expansion is a change in velocity.  A reversion is more like an undoing of what has been done.  We say that Time is unidirectional but science fiction (or maybe fantasy) is filled with stories about multi-directional time.  If we can show that Time is more than just unidirectional (in our own Universe) then I suppose that would mean that our Universe is Transformational, and the implications of such a fundamental principle are profound.  We would have to redefine our (to me somewhat vague) ideas about infinity.

    In fact, another recent article about the oldest known star in the universe appears on the surface to raise a question about our estimates of the age of the universe (although I am sure the question is really about our ability to measure age within Space and Time).  Science would enter a very interesting time if it could be shown there is indeed a star older than the known age of the universe, would it not?  That might be proof that the Universe is Transformational and that we need to redefine how we analyze and discuss Time.

    If, as according to my previous proposition, Complexity Increases Over Time, then we must be in a Transitional Universe -- whereas if Complexity Reorganizes Itself Over Time, then we must be in a Transformational Universe.  I don't see how we can have it both ways.

    Dollo's Law precedes my thoughts on Change and Changefulness.  He might have been on to something much larger than what he had in mind, even if it is all just about probabilities.

    Comments

    Gerhard Adam
    Dollo was trying to establish a criteria that would allow someone to distinguish the same traits that were separated by generations of evolution.  The point being that the same trait may reappear, but it would never occur with exactly the same configuration as previously.  Therefore it would be relatively easy to avoid confusion in being able to separate out the ancestors that had those traits versus its modern day descendants that possessed the same trait.

    Part of the problem with the claim regarding mites is that I'm not clear [nor convinced] that parasitism [at least in this case] is actually a trait.  It would seem that lifestyles are much more fluid than that, and that we need to be cautious about a kind of absolutism in thinking about traits.  It is indicative of viewing everything as being a product of adaptation.

    The primary point regarding Dollo is that certain evolutionary trajectories prevent older, ancestral options from being realized again in the same way. 

    It's actually a rather obvious point since any particular trait is subject to selection and as it changes there is no "memory" of where it came from.  Therefore even if the same type of ancestral species should emerge in the future, it would have done so with a completely different set of initial conditions, so it would be highly unlikely, if not impossible, to expect that it would possess exactly the same genes [or method of expressing traits] as its more primitive ancestor. 

    As a result, a "reversal" cannot happen, because it would require a directionality and purpose that doesn't exist.  There is no evolutionary equivalent to the "UNDO" command.
    Mundus vult decipi
    Michael Martinez
    Thanks for the clarification.  I see what you mean by directionality.  That would suggest that biological evolution is "transformational" (using my own terminology).  I just found an article from MIT in 2011 that offers "qualified support" for Dollo's Law of Irreversibility (I didn't even know that was the full name) in a study where they forced a reversal of adaptation in some bacteria (but they could not do it with much complexity).
    http://web.mit.edu/newsoffice/2011/evolution-reversed-0511.html


    I might look for the follow up study mentioned in the article.  This article raises some interesting questions about what I was planning to publish next on Science 2.0 (I wrote this article on a whim).
    Gerhard Adam
    I guess the primary problem to me is defining what is meant by reversibility.  Clearly this does occur within certain contexts.  Epigenetic factors are routinely "reset" in the germ line, so is that considered reversibility?  Plasmids in bacteria may be selectively used or discarded; is that reversibility?  Other changes brought about by epigenetics may influence several generations and then be dropped; is that reversibility?

    It seems that this is a question that lacks sufficient rigor in defining what exactly is supposed to be reversible.
    Mundus vult decipi
    Michael Martinez
    Obviously it's one thing if we guide it.  It's another for it to happen in nature.  I believe there is a breeding program in Europe that is attempting to bring back the Aurochs.  If I recall correctly, there is some controversy surrounding that program because some biologists say you might end up with a big Aurochs-like animal that is still not an Aurochs.
    If the idea is to roll back time so that we can undo the changes that have been wrought upon various species then I suppose we're dealing with Jurassic Park syndrome.  Even if we can agree on the lexical properties of such endeavors the ethical questions they raise (not to mention the practical questions) will challenge us for a long time to come.

    But what is the purpose of "rolling back the clock"?  There is no one single purpose I am sure but is it a needful thing to do?

    What are we supposed to do with an Aurochs in a Europe that is no longer covered by huge forests?
    Gerhard Adam
    I agree.  It's simply scientific silliness.  Personally I feel that biology is too poorly understood, regarding all the interrelationship of things to engage in such activities.  Just as the movie Jurassic Park portrayed, life has a way of pursuing it's own ends.

    I encounter that with people that are unfamiliar with horses quite a bit.  You tell them that the main advantage of a horse is that you have two brains instead of one when you're moving.  I also mention that this is also a disadvantage because if the horse doesn't trust you, then your brain [or desires] don't count.

    Mundus vult decipi