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From David Tyler: How do computer simulations of evolution relate to the real world?

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The premier computer tool for simulating evolutionary processes has the name Avida. Researchers have reported studies on the evolution of complexity, altruism, changes to genetic architecture, and even the evolution of sex. Avida can be used to illustrate numerous concepts and mechanisms of Darwinian evolution and it has achieved a reputation as a platform for carrying out evolution experiments with digital organisms. As someone who has used simulation as a research tool, the question I have always asked (but to which I have struggled to find a satisfactory answer) concerns validation. It appears that Avida authors have made little or no attempt to cross-validate digital evolution with biological evolution. They have not attempted to move out of their virtual reality world by drawing attention to empirical experiments that give credibility to their conclusions. So how does Avida relate to the real world? At last, a paper has appeared which appears to ask similar questions:

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8 Replies to “From David Tyler: How do computer simulations of evolution relate to the real world?

  1. 1
    ScottAndrews says:

    Mutations that influence fitness by approximately 20% or less come to be dominated by random genetic drift. Mutations that affect fitness by 7.5 – 10.0% or less are entirely invisible to selection in this system.

    This is a significant point. Long-term evolutionary changes (new body plans, new organs, new behaviors, etc.) are supposedly accumulations of tiny incremental changes. But is it realistic to suppose that any one of those incremental changes by itself is going to affect selection?

    Perhaps a field mouse carries a modification that ever so slightly lengthens its forelimbs. Who-knows-how-many mutations later and its descendants could be bats.

    Allowing for the questionable assumption that the initial modification is somehow beneficial – perhaps it can run slightly faster – how much more likely is that mouse to survive and reproduce than any other mouse in the population?

    The darwinian narrative says that a modification is beneficial, gets selected, and so on. But the examples used in practice involve a single change with a clearly defined benefit, such a change in beak size that enables a bird to access the available food supply. It’s all-or-nothing. The bird lives or starves. Individual bacteria are killed out by an antibiotic or are not.

    But all of evolution cannot be explained by such all-or-nothing events. Rather the term “differential reproduction” indicates that individuals with varying traits experience greater success than those without them.

    But going back to new body plans, organs, and behaviors, what specific incremental genetic changes resulting in differential reproduction can be identified that led to such large-scale evolutionary changes? And what reasons can be identified for why they were selected? Identification of any such instances are essential to attributing large-scale evolutionary changes to series of incremental ones.

    Some will argue that individual mutations resulting in differential reproduction are observable. But how can these be related to large-scale evolutionary involving significant new forms and functions? Both individual mutations and significant variations are observed, but what, if anything, connects them?

  2. 2
    PaV says:

    I’ve worked with the “ev” program, and just like with Avida, they use a selection rate of 1.0. I think there are options which allow a lower selection rate; but when it’s lower than 1.0, nothing happens.

    These digital evolutionary programs give an unrealistic picture of supposed evolutionary dynamics.

    Thanks to the authors for their analysis.

  3. 3
    Upright BiPed says:

    Evolutionary algorithms suffer the same flaw as evolution itself, they simply assume what must be demonstrated – the rise of recorded information. The assumption persist because we wouldn’t want physical evidence to distract from the promotion of worldviews based on physical evidence.

    This deformity in logic is, of course, vigorously defended.

  4. 4
    steveO says:

    The Avida paper references this one:

    The frailty of adaptive hypotheses…

    In this paper are listed some evolutionary myths and alleged realities.

    Examples:

    Myth:
    Evolution is natural selection
    Reality:
    Natural selection is just one of four primary evolutionary forces

    Agency is not listed as one of the forces. Tut tut!

    Myth:
    Natural selection promotes the evolution of organismal complexity
    Reality:
    There is no evidence at any level of biological organization that natural
    selection is a directional force encouraging complexity…

    I wonder if a depth of gratitude is owed to the ID scientific community for this particular reality check?

    Now here’s another:

    Myth:
    Microevolutionary theory based on gene-frequency change is
    incapable of explaining the evolution of complex phenotypes.
    Reality:
    No principle of population genetics has been overturned by an
    observation in molecular, cellular, or developmental biology, nor has
    any novel mechanism of evolution been revealed by such fields.

    I’m having problems parsing this one let alone accepting it as reality! Can anyone shed light here?

  5. 5
    Petrushka says:

    I wonder if a depth of gratitude is owed to the ID scientific community for this particular reality check?

    I don’t know, but Gould wrote an entire book about this about thirty years ago. I’m sure you know which one I’m talking about.

  6. 6
    steveO says:

    Would it be much trouble for you provide some quotes from this book that dare not speak it’s name, showing where and how Gould demonstrated that:

    There is no evidence at any level of biological organization that natural selection is a directional force encouraging complexity…

    Thanks!

  7. 7
    Eocene says:

    PaV:

    “These digital evolutionary programs give an unrealistic picture of supposed evolutionary dynamics.”
    =====

    Absolutely true and the major hurdle for them is their own intelligent designing fingerprints imputing information based on their own biased imagination. If you actually look at the site’s own explanation of how it describes itself, it really says it all. If they can’t explain passed their own intelligent imput, any arguments about what is and what isn’t are totally a waste of time. These programs ONLY work the way they want because as they admit, it only works because it has pre-designed goals and fitness functions which were breathed into the program by intelligent designers. The only thing truly going on is the misuse and abuse of intelligence itself.

    Introduction – WHAT IS AVIDA?:
    http://www.krl.caltech.edu/avida/manual/intro.html
    “The population adapts to the combination of an intrinsic fitness landscape (self-reproduction) and an externally imposed (extrinsic) fitness function provided by the researcher.”

    Notice the TIERRA coding system isn’t any better:
    http://life.ou.edu/tierra/whatis.html
    “The Tierra C source code creates a virtual computer and its Darwinian operating system, whose architecture has been designed in such a way that the executable machine codes are evolvable…the machine code can be mutated (by flipping bits at random) or recombined (by swapping segments of code between algorithms)”

    There it is again. Admitting it is designed by the intelligence of the researchers. Unless they can explain past their own cheating and hijacking of intelligent designing concepts that they continually make fun of, yet plagerize without reservation, any further discussion is a worthless effort.

  8. 8

    “they simply assume what must be demonstrated”

    This is a very critical point. In particular, the famous Avida paper that received so much attention (which we have been discussing on another thread) was primarily an exercise in circular question begging (in addition to all the lesser, but perfectly valid, questions about whether it accurately reflected biotic reality, etc.)

    http://www.uncommondescent.com.....darwinism/

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