2011-11-12

Monkeys, Typewriters and Evolution

by Neil Godfrey
The Blind Watchmaker

Probably most people curious enough to read a blog like this will know well enough already Richard Dawkins’ answer to the creationists’ analogy of the probability of monkeys typing the works of Shakespeare being used to debunk the idea of evolution.

But for the benefit of the random reader (as remotely likely and also possible as 2 monkeys with two typewriters typing two 2 character words — don’t forget punctuation keys, spaces, capitalization, numbers, etc) who has not encountered what is probably the simplest rebuttal of all of this “works-of-Shakespeare-typed-by-a-million-monkeys-at-typewriters” analogy, here is evolutionist Richard Dawkins’ rebuttal. He kind of substitutes weasels for monkeys as the main focus of attention, and then switches their roles from actants to objects, but no matter. The point is to demonstrate something real by means of a real (i.e. legitimate) analogy, and monkeys can still be kept in there as the behind-the-scenes typists.

So if we postulate that the primary mechanism of evolution is natural selection, then we will understand that natural selection favours certain genetic configurations over others. Those particular configurations that it favours for survival will be more likely to survive than the others. This is the classical model of the theory of evolution.

So with a nod to rationalwiki here is Dawkin’s monkey (sorry, WEASEL) analogy:

So much for single-step selection of random variation. What about cumulative selection; how much more effective should this be? Very very much more effective, perhaps more so than we at first realize, although it is almost obvious when we reflect further. We again use our computer monkey, but with a crucial difference in its program. It again begins by choosing a random sequence of 28 letters, just as before:

WDLTMNLT DTJBKWIRZREZLMQCO P

It now ‘breeds from’ this random phrase. It duplicates it repeatedly, but with a certain chance of random error – ‘mutation’ – in the copying. The computer examines the mutant nonsense phrases, the ‘progeny’ of the original phrase, and chooses the one which, however slightly, most resembles the target phrase, METHINKS IT IS LIKE A WEASEL. In this instance the winning phrase of the next ‘generation’ happened to be:

WDLTMNLT DTJBSWIRZREZLMQCO P

Not an obvious improvement! But the procedure is repeated, again mutant ‘progeny’ are ‘bred from’ the phrase, and a new ‘winner’ is chosen. This goes on, generation after generation. After 10 generations, the phrase chosen for ‘breeding’ was:

MDLDMNLS ITpSWHRZREZ MECS P

After 20 generations it was:

MELDINLS IT ISWPRKE Z WECSEL

By now, the eye of faith fancies that it can see a resemblance to the target phrase. By 30 generations there can be no doubt:

METHINGS IT ISWLIKE B WECSEL

Generation 40 takes us to within one letter of the target:

METHINKS IT IS LIKE I WEASEL

And the target was finally reached in generation 43. A second run of the computer began with the phrase:

Y YVMQKZPFfXWVHGLAWFVCHQXYOPY,

passed through (again reporting only every tenth generation):

Y YVMQKSPFTXWSHLIKEFV HQYSPY

YETHINKSPITXISHLIKEFA WQYSEY

METHINKS IT ISSLIKE A WEFSEY

METHINKS IT ISBLIKE A WEASES

METHINKS IT ISJLIKE A WEASEO

METHINKS IT IS LIKE A WEASEP

and reached the target phrase in generation 64. m a third run the computer started with:

GEWRGZRPBCTPGQMCKHFDBGW ZCCF

and reached METHINKS IT IS LIKE A WEASEL in 41 generations of selective ‘breeding’.

There is a little macro or whatever at http://rationalwiki.org/wiki/Dawkins_weasel#cite_ref-1 where you can see this evolutionary process in action for yourself. One time I tried it I almost thought I saw only 7 iterations (i.e. generations) to complete the process. But obviously that is the sort of “luck” that defies anything we might expect in the real world. So try it again and see how many times it takes more than 70 iterations to achieve the goal!

I think this scientific response to the creationist analogy has more persuasive power than any efforts by befuddled theologians (e.g. James McGrath on Exploring Our Matrix) who are offended enough to modify the analogy to have monkeys use mere 4 key typewriters!

The Dawkins’ explanation is from his book The Blind Watchmaker

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  • 2011-11-13 09:03:49 UTC - 09:03 | Permalink

    Computational science has developed the sort of evolution thought up in the monkey typewriter scheme…but it is guided by algorithms judging the ‘fitness’ each generation by some at least vague idea of what is desired as the end result. A computer is no smarter than a monkey, and its random alterations of letters is no more brilliant. But if it has an algorithm to guide it…it can do exactly what we expect. Funny that the only way evolution can be modeled computationally is as a guided process. I think that ought to tell us something.

    • 2011-11-13 09:12:11 UTC - 09:12 | Permalink

      The “guiding” mechanism is natural selection. A nervous system that produces sensitivity to light may have a survival advantage over one without that — and as this sensitivity improves right through to the eye of an eagle or octopus so does its advantage. That is the “guiding mechanism” — enhanced chance of survival.

    • 2011-11-13 14:39:57 UTC - 14:39 | Permalink

      Rey: “But if it has an algorithm to guide it…it can do exactly what we expect.”

      The algorithm is meant to simulate an environment that confers an advantage on the “offspring” that fit certain criteria.

      Rey: “Funny that the only way evolution can be modeled computationally is as a guided process.”

      There’s nothing funny about it. The “guided process” simulates a natural advantage. The virus colony in my nasal passages right now have evolved to outsmart my immune system — at least for now. And they’re making me miserable.

      However, there was no intelligent process that caused them to mutate this way; it’s simply how nature works. In a computer simulation, we simulate a natural system in which certain gene combinations have an advantage. (By advantage, we mean: “They get to reproduce.”)

      Rey: “I think that ought to tell us something.”

      What’s that supposed to mean? Rey, this isn’t hard. Try to stay focused. Ready? OK, here goes. In each generation there are random mutations. If one of those mutations happens to confer an advantage, they survive. In each successive generation, these gene combinations are passed on.

      Rey: “…but it is guided by algorithms judging the ‘fitness’ each generation by some at least vague idea of what is desired as the end result.”

      The “desired end result” is simply part of the experiment. It is an artificial goal. In nature there is no goal other than survival. The only end result that counts is whether you reproduce and that your offspring survive and reproduce. If not, “Game Over.” If your offspring happen to be able to survive the next plague, then you’re one of the lucky ones. If they don’t, then they weren’t fit to survive. They might have been prettier. They might have been smarter. But only the organisms that happen to survive get to reproduce.

      • 2011-11-13 17:25:00 UTC - 17:25 | Permalink

        Would the monkeys or a computer ever arrive at shakespear without a guide? Say the guide was a natural selection, just a check that the words were real words. They still would never arrive at shakespear. They need more of a guide than that. And so does evolution. Monkeys still exist. It wasn’t survivability that turned monkeys into humans, since monkeys can survive just fine. Survivability is not the guiding principle in evolution.

        • 2011-11-14 08:57:39 UTC - 08:57 | Permalink

          Monkeys still exist. It wasn’t survivability that turned monkeys into humans, since monkeys can survive just fine.

          Monkeys did not turn into humans and I have never read a text about evolution that says they did. The idea of “turning into” another species misses the whole idea of evolution. There is no point at which anyone would be able to say, Ah ha, this is where species y begins or starts to grow out from species x, or here is where species x begins to ‘turn into’ species y. The fossil tree represents markers millions of years apart. If it is only over vast time spans that we can notice differences it is misleading to say that x turns into y. One might equally say that species y is one of the variant shapes and structures of species x adapted to survive through major environmental shifts over eons.

          • Evan
            2011-11-15 02:24:04 UTC - 02:24 | Permalink

            Neil, all that you say is correct. But if we looked at the common ancestor that modern humans and modern monkeys share, we would say that it was a monkey. I have no problem with this, but some people seem adamant that we didn’t arise from monkeys, and it seems obvious to me that in the vernacular sense of the term we obviously did.

            • 2011-11-15 07:07:39 UTC - 07:07 | Permalink

              My comment was an attempt to address Rey’s very specific reference to monkeys where he was arguing that monkeys exist today as monkeys and for that reason it can be said that they did not “turn into” humans.

      • Evan
        2011-11-15 02:22:10 UTC - 02:22 | Permalink

        Tim, actually, the virus is pretty benign, it is simply using your nasal passages to propagate itself. It is your immune system itself that is making you miserable …

        • 2011-11-15 05:18:50 UTC - 05:18 | Permalink

          To quote Don Martin, “It isn’t the pain — it’s the pressure of the drill on the exposed nerve.”

  • 2011-11-14 01:54:01 UTC - 01:54 | Permalink

    > “Survivability is not the guiding principle in evolution.”

    I wouldn’t call it a “guiding principle,” because evolution is not guided. However, survivability is a primary driver of evolution. Since there is an overwhelming amount evidence against your assertion, you might want to provide some counter-evidence of your own. Please note that “I don’t understand how” is not evidence, nor does it even count as an argument.

    Just saying you can’t imagine human labor building the Great Pyramid of Giza doesn’t mean it didn’t happen that way, nor does it prove that aliens from another world came down to help. And just because you can’t imagine, as Dennett describes it, thousands of little cranes doing the heavy lifting of evolution, that doesn’t mean skyhooks exist.

    • 2011-11-14 01:55:48 UTC - 01:55 | Permalink

      [Note: That comment should have appeared under reyjacobs' comment in which he mistakenly says monkeys turned into humans.]

  • rey
    2011-11-15 13:23:16 UTC - 13:23 | Permalink

    “Just saying you can’t imagine human labor building the Great Pyramid of Giza doesn’t mean it didn’t happen that way, nor does it prove that aliens from another world came down to help.”

    Maybe the mythical monkeys that turned into humans built the pyramids.

  • Otishpote
    2011-11-15 15:49:22 UTC - 15:49 | Permalink

    The example given by Dawkins is very weak. It isn’t measuring fitness at each step, but is simply measuring similarity to a predetermined ad hoc goal. It is a good initial step in explaining how evolution may take advantage of parallelism. But, it doesn’t really succeed at demonstrating how (or even the mere fact that) evolution actually works.

    Teams of computer scientists and engineers have come up with radically more impressive computer simulations of evolution.
    http://www.eecs.harvard.edu/~rad/courses/cs266/papers/koza-sciam03.pdf

    Using what are called “genetic algorithms”, researchers have been able to produce designs for new patentable devices. It is not known in advance how, or even if, the computer will successfully solve the problem it is given – which is simply to design some device that meets (or comes closest to meeting) certain desired specifications. Often the computer does solve the problem quite brilliantly. In several cases the evolved devices turned out to work significantly better than any previous design from human engineers trying to solve the same problem. And the evolved designs often have complex features that require intense study by the scientists involved just to understand how they work. That demonstrates conclusively that evolution can be creative, finding novel and often complex solutions to problems. That is a particular point that many creationists have a problem with.

  • Otishpote
    2011-11-15 15:49:49 UTC - 15:49 | Permalink

    It is also worth pointing out that the contrast between intelligent design and evolution is to some extent a false dichotomy – as both fundamentally involve analogous processes. Both randomly try variations on a ideas to see if one of the new variations works better than the starting idea. The one significant difference between physical evolution and intelligent design by humans is simply that physical evolution tests each variation in the real world; intelligent design saves resources by testing most of them in a virtual mental world, and only expending the resources to make physical models of the ones that seem most promising.

    I find it interesting and illuminating how many seemingly simple human inventions have taken many years and many steps to get to their current forms. For example, in chapter one of “The Evolution of Useful Things”, Henry Petroski details how it took hundreds of years for the table fork to come to have the particular form it most commonly has today.

    • 2011-11-15 16:29:39 UTC - 16:29 | Permalink

      The problem I have with your statement is that people who champion intelligent design have in mind a particular designer, namely the God of the King James Version of the Bible.

      > The one significant difference between physical evolution and intelligent design by humans is simply that physical evolution tests each variation in the real world; intelligent design saves resources by testing most of them in a virtual mental world, and only expending the resources to make physical models of the ones that seem most promising.

      [...intelligent design by humans...?]

      This “mental world” would apparently exist in the infinite mind of God, who guides evolution with his mighty hand and outstretched arm. Apparently, he designed bacterial flagella to give us a sign that he cares about the important things in this world. And what does the all-powerful creator of the universe seek to draw our attention to? Starvation? War? Disease? Misery? Injustice?

      Of course not. It’s irreducible complexity. http://www.talkorigins.org/faqs/behe.html

      If this is what God thinks is important, then either we were created by a psychopath or it’s all horseshit. I prefer to think that it’s all horseshit.

      • Otishpote
        2011-11-16 00:16:41 UTC - 00:16 | Permalink

        >The problem I have with your statement is that people who champion intelligent design have in mind a particular designer, namely the God of the King James Version of the Bible.

        Your comments are irrelevant to what I wrote. Didn’t the context, the examples I gave, and my explicitly clarifying “by humans”, each make it clear that I wasn’t referring at all to creationism? I was leaving God out of it, since I prefer to talk about reality not fiction, and since mention of God was immaterial to the discussion at hand: ways of demonstrating that natural selection and similar processes have creative power.

        Anyway, I was merely pointing out, that in a way, variation and selection is behind creative processes even outside of biology, giving a specific example of human artifacts such as forks.

        >This “mental world” would apparently exist in the infinite mind of God.

        No. Not if by “this” you mean to refer to anything I was discussing in my prior comment.

        If an omniscient God existed, it would transcend any form of mental processing. It would not need to think through, figure out, or make up its mind about anything. Since it is presumed to already know everything, there is never anything left for it to figure out.

        • pearl
          2011-11-16 04:32:51 UTC - 04:32 | Permalink

          Just as the term “intelligent design” can evoke different connotations for different people, so can the word “creative”. P. J. Bentley addressed some ideas in ”Is Evolution Creative?”

  • Dr Mohammed A. Azzam
    2011-11-16 08:12:18 UTC - 08:12 | Permalink

    The problem is that the random phrase “WDLTMNLT DTJBKWIRZREZLMQCO P” does not possess any filtering mechanism built in, survival or otherwise! Nor the weasels on the keyboards! Once you postulate such a guiding mechanism, not to mention a target phrase, you have already conceded ID!
    Please note that Dawkins used the term “target phrase”!

    • 2011-11-16 10:35:11 UTC - 10:35 | Permalink

      Dr. Azzam: “…does not possess any filtering mechanism built in, survival or otherwise!”

      Nor does the phrase possess any innate ability to reproduce. It’s what we call “an experiment.” It simulates the natural world.

      Dr Azzam: “Once you postulate such a guiding mechanism, not to mention a target phrase, you have already conceded ID!”

      Ummm… No. The external constraints mimic environmental pressures. The reproduction phase simulates sexual reproduction in nature. The random mistakes represent natural mutations that occur in each generation.

      It would be senseless not to have any experimental constraint on what survives to reproduce. That’s the whole point of the experiment. However, since this seems to be a stumbling block for people, consider this experiment:

      http://www.newscientist.com/article/dn14094-bacteria-make-major-evolutionary-shift-in-the-lab.html

      Note that the researchers were simply observing the changes of the bacteria over many generations. They didn’t plan for the E. coli to start eating citrate; it just happened. This newly acquired trait conferred a distinct advantage, such that “the citrate-using mutants increased in population size and diversity.”

  • Dr Mohammed A. Azzam
    2011-11-17 08:59:16 UTC - 08:59 | Permalink

    To Mr Tim Widowfield;
    (1) It turns out that Dawkins himself acknowledged my point:
    As Dawkins acknowledges, however, the weasel program is an imperfect analogy for evolution, as “offspring” phrases were selected “according to the criterion of resemblance to a distant ideal target.” In contrast, Dawkins affirms, evolution has no long-term plans and does not progress toward some distant goal (such as humans). The weasel program is instead meant to illustrate the difference between nonrandom cumulative selection, and random single-step selection.
    http://en.wikipedia.org/wiki/Infinite_monkey_theorem

    Simply put, if evolution has no long-term plans, then the weasel analogy falls apart, because it is based on a “target phrase”. Dawkins should have come up with a better example.

    (2) I see no motivation by survival or natural selection in “E. coli learning to eat citrate”. In fact, 31,000+ generations in the experiment did very well without lemonade!

    • 2011-11-17 11:06:47 UTC - 11:06 | Permalink

      Dr: Azzam: “I see no motivation by survival or natural selection in ‘E. coli learning to eat citrate’.”

      They were not “motivated.” Lamarckianism is dead.

      Ah, but there was “natural selection.” The population that inherited this lucky mutation did in fact prosper. They gained an advantage because there was more for them to eat.

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