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 Post subject: The Greatest Show on Earth, by Richard Dawkins
PostPosted: Thu Aug 04, 2011 11:15 am 
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A workmate has offered me his copy of Richard Dawkins' "The Greatest Show on Earth" to read. I haven't read a Dawkins book from cover to cover before, but I've had cause to read excerpts of them and some of his essays, and my experience to date has given me little cause to think that Dawkins will produce a compelling argument in this book. In my view, Dawkins argues poorly: he often rants and ridicules his opponents when he should be building his own case. Even so, Dawkins is arguably the foremost contemporary spokesperson for philosophical materialism (and the things that fall under its umbrella, such as atheism, evolution, and scientific rationalism), so I'm going to accept the challenge presented by this book.

I'm a creationist, as anyone who peruses any of my writing is likely to know already, but I'm also a believer in John Stuart Mill's idea that we only gain a true and proper appreciation of our own points of view when we acquaint ourselves with the views of our ideological opponents -- not via our own teachers, who interpret and accompany the interpretation with counter-arguments, but directly, from those who believe the things in earnest. I therefore read this book with the honest intention of hearing the views of a well-versed ideological opponent: a giant of the field, generally well respected amongst his ideological peers, and whose sincerity is beyond question. Dawkins really, really believes in Evolution, and he's eminently qualified to talk about it.

I will document my thoughts as I go, because past experience and a brief foray into this book tell me that I disagree with Dawkins very frequently -- and also agree with him on occasion. I won't attempt to refute any evidence that he presents -- I'm interested in hearing his take on the evidence, after all -- but I will be critical of his reasoning. Dawkins is a man who prides himself on his rationality, so it's only fair to hold him to a high standard in that regard. In fact, his entire approach to the issue practically demands such intense scrutiny -- but more on that subject as it arises in his book.

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 Post subject: Chapter 1: Only a theory?
PostPosted: Thu Aug 04, 2011 12:30 pm 
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Dawkins spends the first few pages of his book talking about (a) an imaginary group of people who deny that the Roman empire existed, and (b) a real group who deny the Nazi holocaust as a Zionist fabrication. He then invites us to consider evolution deniers as roughly equivalent to these other folks in terms of their own irrationality and their nuisance value to right-thinking people who just want to get on with the job of teaching history. On p.7 he states his intention to use the term "history-deniers" for those people who deny evolution. On p.8, he says "the history-deniers themselves are among those that I am trying to reach in this book."

I note that Dawkins has chosen to open his presentation of the evidence for evolution by ridiculing those who deny it, and inventing a wholly unnecessary and uncharitable name for them. "Evolution-deniers" would have been quite adequate as a term, but apparently it fails to convey his contempt sufficiently. If this is his idea of "trying to reach" someone, then his diplomacy skills are wanting.

From pp.4--8, Dawkins brings the views of religious leaders into the picture. His main point is that certain very prominent religious leaders embrace the theory of evolution, and yet a significant portion of the general public (e.g., "more than 40 per cent of the American population") denies that humans evolved from other animals, instead holding to a supernatural creation in the last ten thousand years. Based on this observation, he coins another term for history-deniers: "40-percenters". He also admonishes the religious leaders in question to be more explicit in their teaching that biblical concepts such as Adam and Eve and original sin are not literally true.

I somewhat agree with Dawkin's call for frankness from religious leaders, but it's off topic (nothing to do with evidence for evolution), so I'll leave it. The persistent popularity of creation theory among the general populace is also interesting, but similarly off topic.

On pp.8--9, Dawkins states his position on certain propositions. Although he has not yet reached the first piece of actual evidence in his presentation, he wishes us to know up front, for example, that "the evidence for evolution is at least as strong as the evidence for the Holocaust, even allowing for eye witnesses to the Holocaust." This is a very strong claim, and I will be expecting justification that his evidence is of a better quality than eye witness testimony once the evidence is actually presented. As to the proposition that "evolution is a fact", he says, "no reputable scientist disputes it, and no unbiased reader will close the book doubting it."

I note in passing that these claims have logical implications, namely: "if you are a scientist who disputes evolution, then you are not reputable; if you read this book and still doubt evolution, then you are not unbiased." In other words, Dawkins has given fair warning that he has already passed judgement on me as a reader: I will either be in agreement, or considered "biased".

I also note in passing that all material so far has been a preamble: there is no argument or reasoning to analyse yet. As a matter of style, I think this preamble would have been better spent constructing a high-level overview of the evidence: some mention of fossils, experiments, and whatever else he plans to introduce as evidence. Inventing derogatory names for your opponents only appeals to those who already share your antipathy towards them.

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 Post subject: Re: Chapter 1: Only a theory?
PostPosted: Thu Aug 04, 2011 4:48 pm 
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On pp.9--13, Dawkins draws a distinction between two meanings of the word "theory". One is a weak sense, suggesting a mere speculation; the other is a strong sense, suggesting explanatory sophistication and significant connection with experienced phenomena. To make the distinction clearer, he uses "hypothesis" for the weak sense of theory (p.10), and coins the word "theorum" (to rhyme with "decorum") for the strong sense (p.11). This is a variation on the mathematical term "theorem", and he compares and contrasts his hypothesis/theorum distinction with the similar mathematical conjecture/theorem distinction. The primary point of contrast is that mathematical proofs (which promote a conjecture to a theorem) are formal constructs which are unattainable in science (p.13). Even so, he suggests that "theorums" are established when they are "supported by massive quantities of evidence, accepted by all informed observers, undisputed facts in the ordinary sense of the word." (p.13)

As part of this explanation, Dawkins offers the "Heliocentric Theory of the Solar System, the theory that Earth and the other planets orbit the sun," as a good example of the strong sense of "theory", or a "theorum". This it may be, but what of the Geocentric Theory which it replaced? Should we deny it the status of a "theorum"? Most people think of it as a religious position rather than a scientific one, but it was both, as is the case with the Theory of Evolution today (a point which Dawkins has already raised by citing religious support for the theory). The Geocentric Theory seems to qualify for the strong sense of "theory" quoted on p.9, or perhaps we should say that underlying theories about the elements of earth, water, air, fire, and ether explained the common-sense observation that the heavens moved in circles around the static Earth.

The problem with granting Geocentricism the status of "theorum", of course, is that these days nobody believes a word of it -- well, nobody that I know of. Geocentricism and its associated implications went from being "supported by massive quantities of evidence, accepted by all informed observers, undisputed facts in the ordinary sense of the word" to, well, the exact opposite of that. And it wasn't new evidence that brought about this change, but rather a reinterpretation of existing evidence along with a lot of new experimentation which was suggested by the new model.

I don't profess to have a deep understanding of the Copernican revolution, but it seems a conspicuous omission to talk about the Heliocentric Theory of the Solar System without mentioning the theory that it overthrew and the scientific revolution that it represented. Dawkins' discussion of hypothesis versus theorum invites a very black and white view of things: we have a term that means "pure speculative conjecture" and another that means "common-sense fact". What of the middle ground? Isn't this a spectrum? And don't things which seem like indisputable common-sense facts sometimes get thrown out? This isn't just an obscure philosophical point or appeal to a deceptive Cartesian demon, and scientific revolutions and paradigm shifts are not simply cases of non-science being replaced with science.

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 Post subject: Re: Chapter 1: Only a theory?
PostPosted: Fri Aug 05, 2011 8:17 pm 
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On pp.13--16, Dawkins talks about the meaning of "fact", and the difference between eye witness testimony and scientific inference. This is important, because it is a clear first step towards supporting his earlier (p.8) claim that the evidence for evolution is better than the evidence for the Holocaust, the former of which necessarily lacks any kind of eye witness testimony. His approach is to emphasise the fallibility of eye witness testimony (p.14), and he supports this claim by reference to a particular experiment by Daniel J. Simmons at the University of Illinois.

In this experiment, the subjects are told that they have a task to perform: they will be shown a video of some people with basketballs, and must count the number of times the balls are passed. When the video is over and the counts are collected, a surprise question is added: "how many of you saw the gorilla?" The majority of participants deny that they saw any gorilla in the video, but on replaying it, a person in a gorilla suit can be clearly seen walking into the middle of frame, beating his chest, and walking out the other side.

Dawkins concludes (p.15), "eye-witness testimony, 'actual observation', 'a datum of experience' -- all are, or at least can be, hopelessly unreliable," and "careful inference can be more reliable than 'actual observation'". He grants the concession that "inference has to be based ultimately on observation by our sense organs," but asserts that "direct observation of an alleged event (such as a murder) as it actually happens is not necessarily more reliable than indirect observation of its consequences (such as DNA in a bloodstain) fed into a well-constructed inference engine."

I take issue with Dawkins' interpretation of the experimental result. It's not that he's wrong about the fallibility of observation and testimony, and the potential reliability of inference, but rather that he ought to be expressing doubt about the scientific process on the same grounds that he disparages eye witness testimony.

The subjects in the experiment are informed up-front that their job is to count the number of times that the balls are passed. As a result of this, they focus on the balls and counting the passes, and this is why they can miss something as conspicuous as a man in a gorilla suit walking through the frame. They see the man in the gorilla suit quite readily when told to relax and not count. The process of science is similar: before becoming a practising scientist, those entering the field are given extensive education on accepted theories ("theorums"), how to conduct experiments, how to operate the associated equipment, and so on. In other words, they are pre-conditioned to perceive the data in a particular way -- much more thoroughly and extensively than the people who are told to count the times that the balls are passed around. As a consequence of this, we should expect -- with a high degree of assurance -- that a great many "gorillas" are present in plain view of all the world's best-trained scientists, and they can't see them precisely because they've been expertly trained to look at something else.

It's quite possible that any given eye witness could be mistaken about what he saw, no matter how emphatically he asserts the veracity of his testimony. Similarly, we should understand that when a competent scientist explains his evidence, he does so with the benefit of significant expertise, but we should be very wary if he claims that the data allow no other interpretation, no matter how emphatically he asserts it. He may well be right -- or he may have failed to notice a gorilla. We ought to expect scientists to have blind spots in areas which are not core to their models because of their training and expertise. To put it another way, it is prudent to doubt the testimony of a scientist who says "there are no gorillas here" if gorillas are not a part of his scientific model.

I grant Dawkins some of his point regarding the fallibility of eye witness testimony, but he hasn't looked at scientific inference through the same lens. To the extent that we accept this "gorilla" effect as a problem, I think it has more particular implications for science than it does for testimony in general. This does not render science useless, but it means that we must take into account the theories to which a particular scientist subscribes when judging the reliability of his testimony.

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 Post subject: Re: Chapter 1: Only a theory?
PostPosted: Sat Aug 06, 2011 11:25 am 
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On p.16, Dawkins emphasises the importance of "proper scientific inference" to his argument: he intends to show "the irrefragable power of the inference that evolution is a fact." (I'll save you a trip to the dictionary, since I've already been there myself: "irrefragable" is a synonym for "irrefutable" or "indisputable".) He points out that most of evolution is either history or too slow to observe, so direct observation is not an option, but that we can piece together the events of the past in the manner of a detective by looking at the physical evidence.

I have some slight reservations about these remarks. Does Dawkins intend to demonstrate the potency of "proper scientific inference" in some way? What qualifies an inference as "proper" and "scientific"? Does he plan to cover these issues? If he does not, then it is going to seriously undermine whatever evidence he presents later in the book. It's not possible to scrutinise an argument if it consists of "observable facts X, Y, and Z imply conclusion C by process of proper scientific inference" when the inner workings of "proper scientific inference" are not known. Ideally what we need is a precise definition of the scientific inference machine, plus a few good demonstrations that the inference process works reliably in circumstances where the conclusion can be independently verified. In other words, we need to be able to check the machine against cases where we already know what result it should produce.

I guess we'll need to be on the lookout for this kind of information later in the book: it is not present in Chapter 1.

On pp.16--18, Dawkins makes a few more remarks about the hypothesis/theorum distinction, and how there is not an unbridgeable chasm between them. He points out that many theorums begin as hypotheses, citing the theory of continental drift as an example. He also says (p.17), "the fact that some widely held past beliefs have been conclusively proved erroneous doesn't mean we have to fear that future evidence will always show our present beliefs to be wrong." This is, perhaps, a nod to the fall of Geocentricism, or other theories like it. He goes on to say, "people used to think that the sun was smaller than the Earth, because they had inadequate evidence. Now we have evidence, which was not previously available, that shows conclusively that it is much larger, and we can be totally confident that this evidence will never, ever be superseded." He goes on to say that Evolution and the Heliocentric theory have also reached this level of certainty.

While I personally agree that it's inconceivable that any new evidence could arise to contradict our belief that the sun is bigger than the Earth, we don't have a clear cut set of conditions which establish this objectively. By this, I mean that you can ask around, and see if anyone thinks that any possible evidence could arise to make them change their mind about the relative size of the Earth and sun, and I expect that all the coherent answers would be "no", but this merely establishes group consensus on an interpretation of the evidence. Clearly this kind of group consensus is not what Dawkins has in mind, because there are plenty of people who disagree on the truth of Evolution. Of course, Dawkins has already made it clear that evolution is a consensus belief among reputable scientists, but if denying evolution is enough to automatically make a person "not reputable", then this is just a circular argument -- an elaborate way of saying "evolution is a consensus belief among scientists who believe in evolution".

We need a more objective way to measure the certainty of a theory, but Dawkins has not as yet given any clear description of it.

There is another (more obscure) problem with the idea that sufficient evidence can establish a scientific theory permanently. I don't think it's a terribly important point in the current context, so I'll try to keep it brief. Scientific theories come with an ontology -- a set of terms which describe things or properties of things that are supposed to exist. In the question of whether the sun is bigger than the Earth, we can see that the very question assumes the existence not only of the sun and Earth, but of a property called "size" which can be measured in some way. This, in turn, assumes some kind of geometric system of measurement. Most of us think in terms of Euclidean geometry when we think of geometry at all, but it's not the only game in town. Furthermore, we tend to think of "size" as an independent property, not dependent on where the object is, for example, but this isn't a given either. Relativity says that size changes with velocity (or acceleration, or something -- I'm not a physicist), so if we take relativity into consideration, then the answer is "sure, the sun is bigger than the Earth at the moment, but we could (in principle) make the Earth bigger by accelerating it to near the speed of light."

The point is that even when a statement seems absolutely certain, given the evidence, a new scientific model can arise which uses a different ontology, and in which something like "size" has different properties. The point is that even when the answer to a question seems absolutely certain, sometimes a new model comes along which makes the whole question look wrong.

On pp.17--18, Dawkins describes the elevation of Evolution from hypothesis to theorum, noting that it was indeed a questionable theory when Darwin first introduced it, but that it has now risen to the level of "fact" (in the informal sense). From this it is fairly clear that Dawkins recognises that "hypothesis" and "theorum" are the opposite extremes of a continuum (rather than one of two possible classifications), but as yet he has still only alluded to the middle ground. I'm still on the lookout for more detail about this progression, because it is important to his assertion that there can be such a thing as a "theorum", and that Evolution is one. In particular, if this is a valid model of scientific knowledge, how do we measure the position of a theory on the hypothesis/theorum continuum?

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 Post subject: Chapter 2: Dogs, Cows and Cabbages
PostPosted: Sun Aug 07, 2011 11:11 am 
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Chapter two of The Greatest Show on Earth is primarily about two subjects. It starts by asking (and answering) why it took so long for there to be a theory like evolution, which treated all life as universally interrelated rather than as groups of separate and distinct entities (pp.21--27). The chapter then goes on to talk about gene pools, variation, and selective breeding (pp.27--42). As with chapter one, chapter two contains no evidence for evolution as such: at the very end of the chapter, Dawkins says that this is still a "softening up" phase, and that chapter three will continue along the same lines.

It's not clear to me why Dawkins wants to introduce the first of these topics into the discussion at all. What is this speculation about the history of science supposed to achieve? Perhaps it's intended as a pre-emptive strike against those who might think that if the evidence points as clearly to evolution as he says it does, then we should have figured it out long ago. Whatever the case, he may use the ideas presented here to support arguments presented later in the book, so I'd better give it critical analysis rather than declare it off topic and skip over it.

In framing the question, Dawkins suggests that Darwin's view was a revolutionary one, or he at least makes no mention of similar ideas significantly prior to Darwin. Rather, he points to Plato's philosophy of ideal forms (or "essentialism") as the main driver of non-evolutionary thinking. On p.23, he says (citing Ernst Mayr), "the reason Darwin was such an unconscionable time arriving on the scene was that we all -- whether because of Greek influence or for some other reason -- have essentialism burned into our mental DNA."

Contrary to Dawkins, the Internet Encyclopedia of Philosophy's entry on the History of Evolution says, "Evolution is not so much a modern discovery as some of its advocates would have us believe." (I think it's safe to consider it a credible source of information on Ancient Greek thought: this is a peer reviewed source, not Wikipedia.) A small excerpt goes a long way towards rebuffing Dawkins' presentation, so I reproduce the following extract from the first paragraph of part one.

Quote:
Anaximander is often regarded as a precursor of the modem theory of development. He deduces living beings, in a gradual development, from moisture under the influence of warmth, and suggests the view that men originated from animals of another sort, since if they had come into existence as human beings, needing fostering care for a long time, they would not have been able to maintain their existence. In Empedocles, as in Epicurus and Lucretius, who follow in Hs footsteps, there are rudimentary suggestions of the Darwinian theory in its broader sense; and here too, as with Darwin, the mechanical principle comes in; the process is adapted to a certain end by a sort of natural selection, without regarding nature as deliberately forming its results for these ends.

This is only a small sample of particularly mechanistic theories: there were other theories of gradual development besides, but they postulated a kind of purpose-driven development. In any case, the idea that man arose from animals is an ancient one. Granted, this kind of developmental history was never the dominant idea until Darwin presented his argument for it, but the idea has been available for a very long time. It's not clear that this long-term lack of popularity matters to Evolution as a scientific theory, though, one way or the other. So long as Dawkins doesn't rely on this "predisposition to essentialism" claim as the basis for something else further down the track, I think we can safely ignore it as an irrelevant side issue.

There still remain a couple of issues that need to be addressed, however. On pp.23--27, Dawkins invites us to imagine an excursion up the (maternal) ancestral tree from a modern rabbit, back to an ancestor shared by rabbits and leopards, and then back down again to the modern leopard. The concept itself is straightforward enough (if you grant the truth of common ancestry for the sake of argument), but there are still a couple of associated remarks which bear comment.

The first of these comments is that Dawkins presents an adamantly gradualist illustration of the process. The upward change (toward the common ancestor) is characterised as "steadily and imperceptibly", and then the downward change (towards the modern leopard) happens "slowly, by imperceptible degrees", until "eventually without ever noticing an abrupt change of any kind, we arrive at a leopard." This thought experiment is followed by four points, the fourth of which simply re-emphasises the gradual nature of the process.

Why is Dawkins so adamant that this process must be imperceptibly gradual? Leopards have spots, and rabbits don't, and I'm trying to decide what sort of transition I should be imagining between the two. A gradual and imperceptible darkening of the spots and lightening of the non-spots? That's not really gradual, since it requires both ends of the transition to technically have the same kinds of spots, merely at different contrast ratios. Perhaps we would do better to imagine the transition as a change in pattern size, starting with it being so big on the rabbit that it is essentially a single spot, then becoming smaller through the transition such that the number of spots increases. I find it simpler to suppose that there was a sudden "spotty" mutation that happened somewhere in leopard ancestry: a conspicuous change between mother and child. Must every change be slow and imperceptible?

Dawkins hasn't told us why his adamant stance on gradualism is important yet, so we'll just have to file that question away for future reference.

The other issue I have is on pp.26--27 where Dawkins talks of "immutability of species" as though it were derived from the philosophy of essentialism. I think this puts the cart before the horse. The immutability of species -- or of something slightly more general than a species, perhaps -- is an observable phenomenon. You don't need to be remotely "essentialist" in your outlook to experience biological boundaries between different kinds of animals. Dawkins is about to spend a lot of time talking about selective breeding, and if there's one thing that selective breeding has taught us, it's that X comes from X, where X is the kind of thing you are breeding, be it dogs, pigeons, cattle, or whatever. No amount of pigeon-breeding is going to get you a dog, or even a duck.

Now, I realise that Darwin invites us (as does Dawkins) to imagine this process continuing without limit over vast quantities of time, but actual experience gives us reason to think that there are boundaries that can not be crossed. Dawkins will discuss some of these in upcoming pages, such as the length of the dog's snout (p.36). "Immutability of species" is a scientific-sounding but not very accurate way of describing this phenomenon: the experience is better summarised as, "variation exists, but has limits". If you happen to be an essentialist, you will see this as perfectly compatible with your views: no real form matches the ideal, but no real form can stray too far from its ideal. (Perhaps this is why essentialism has been so popular, historically: simple compatibility with experience?) On the other hand, this phenomenon is readily experienced whether or not one is inclined towards essentialism, and it takes a lot of special pleading on Darwin's part to persuade us that these apparent limits can be breached.

My objection here is that Dawkins makes it sound like "variation has limits" is an idea derived from pure philosophy, divorced from reality. It isn't, and we would do well to remember this. When the time comes, we must demand a good argument as to why our experience (of variation having limits) is misleading, and we should not let Dawkins dismiss the evidence with a simple claim of "predisposition to essentialism".

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 Post subject: Re: Chapter 2: Dogs, Cows and Cabbages
PostPosted: Thu Aug 11, 2011 1:29 pm 
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Moving on to the subject of "sculpting the gene pool" (as the subheading says), Dawkins remarks (p.27) that "cabbages are a vegetable affront to essentialism and the immutability of species." They may be that, for certain values of "essentialism" and "immutability", but they are still examples of variation within limits, as discussed above. The degree of variation is quite remarkable, to be sure: who would guess that broccoli and Brussels sprouts are related in more ways than just the reaction that children have to them when encountered on the dinner plate?

Given this immense range of variation, it's perhaps surprising that cabbage and lettuce aren't related (at least, not in the verifiable way that cabbage and broccoli are). You'd think that a basic cabbage and a basic iceberg lettuce would have more in common than cabbage and broccoli, just to look at them, but apparently not. You can breed cabbage into broccoli, but you can't breed it into lettuce. You might be able to produce a more lettuce-like cabbage if you care to try, but it will still be a cabbage, not a lettuce.

Dawkins is emphasising the variation -- fair enough -- but don't let that distract you from the fact that we experience variation within limits. There's a difference between "immutable" and "variation within limits" (given a sufficiently strict meaning of "immutable"), and we mustn't be lulled into accepting "variation without limits" (one of Evolution's ultimate claims) by simple refutation of a strict "immutable".

From pp.27--39, Dawkins talks about genes, gene pools, and selective breeding, particularly of dogs. This is provided as background information -- groundwork for future arguments and interpretation of evidence. On p.28, he says, "the main point I want to draw out of domestication is its astonishing power to change the shape and behaviour of wild animals, and the speed with which it does so." This seems like a fair characterisation of the facts. The "speed" of which he speaks is measured in generations, of course, but most animals reach sexual maturity much more quickly than humans, so striking results can be obtained in substantially less than a human lifespan, given the appropriate animals.

On pp.29,32 Dawkins uses the analogy of a deck of cards to illustrate the discrete nature of genetic information. The points he raises (primarily contrasting it with the analogy of blending paints) are fair and reasonable, but I have a slight nit to pick. On p.32, he says, "if we take a long view across many generations, we see all the rat genes on the island being mixed up as though they were cards in a single well-shuffled pack: one single pool of genes." Strictly speaking, this isn't true: the relative frequency of cards in a deck doesn't change, whereas the relative frequency of genes does, even if only at random. He goes on to mention gene frequency on p.33, so the deck of cards is just a slightly sloppy analogy -- not something that needs to be emphasised as misleading.

What is misleading, however, is his claim (p.33) that, "when there is a systematic increase or decrease in the frequency with which we see a particular gene in a gene pool, that is precisely and exactly what is meant by evolution." Precisely and exactly? Back on p.17 he referred to "the fact of evolution (all living things are cousins)", which is a meaning of "evolution" significantly removed from "systematic change in gene frequency". Clearly his own usage of the term is not so precise or exact as he claims, and we must scrutinise his use of the word on a case by case basis to determine which meaning he intends.

Overloading a word like "evolution" with multiple distinct meanings like this can lead to equivocation, where the sense of a word is changed mid-argument, with logically fallacious results. Dawkins would probably like us to accept that "systematic change in gene frequency" is exactly the same as "all living things are related", but we require evidence for this proposition, and must not be tricked into accepting it simply because he uses "evolution" as a term for both things.

On p.35, Dawkins says, "breeds of dog with very short legs, like basset hounds and dachshunds, acquired them in a single step with the genetic mutation called achondroplasia, a classic example of a large mutation that would be unlikely to survive in nature." Granted that the particular mutation would not likely survive in nature, it does show that sudden mutation is possible. I questioned earlier whether the leopard might not have acquired its spots suddenly in its ancestry. The sudden acquisition of spots due to a mutation might provide a camouflage benefit, or at least be neutral, thus allowing the new trait to be passed on. I note this primarily because Dawkins has been quite adamant about gradualism (as discussed earlier), and we need to be on the lookout for evidence against it (or at least a lack of decisive evidence for it) in his own data.

In summarising the lessons learned from the domestication of dogs, Dawkins says (p.37), "the changes are so large -- the differences between breeds so dramatic -- that you might expect their evolution to take millions of years instead of just a matter of centuries." Note that the evidence is contrary to the expectation: you would only be surprised by the data if you already believed that change was imperceptibly slow and gradual. The lesson to be learned from dog breeding is that significant change is possible in a short time, if the raw genetic material is already present and just needs to be sifted out.

Dawkins goes on to say, "if so much evolutionary change can be achieved in just a few centuries or even decades, just think what might be achieved in ten or a hundred million years." The belief that more time will allow for proportionately more change is based on the assumption that change can occur without limits, but the data already presented by Dawkins here contradicts that assumption. We've seen discussion of dogs' snouts, which are already bred so short as to produce respiratory problems, and so long as to limit the abilities of puppies to suck their mother's milk. Selective breeders like to push these traits to the extreme, and experience shows that pushing the limits tends to result in health issues: pedigree dogs are often associated with particular ailments which are related to their selected traits.

By way of illustration, imagine a dog in a field, restrained by a long, sturdy rope that is firmly held at one end by a large tent peg in the middle of the field. This dog has plenty of room to move, because its tether is a long one, but once it reaches the limits of its tether, it will hurt itself if it tries to press on any further. The dog gene pool is a lot like that: there is room for enormous variation in size, build, behaviour, fur, and so on, but you reach a limit as to what can be achieved, and you generally start to introduce complications the harder you push the boundaries. To suggest that more could be achieved given more time contradicts our experience with selective breeding. Analogously, the dog in the field may be able to move quite quickly from place to place inside his boundaries, but we can't extrapolate that movement beyond those bounds: extra time isn't going to get him anywhere new, no matter how much you give him.

Dawkins needs to demonstrate that these boundaries can be overcome, otherwise his extrapolation is meaningless. File this requirement away for future reference.

On the other hand, I approve of Dawkins' emphasis that selective breeding is primarily a genetically subtractive process (p.37). This is an important point to make, particularly given that it is an aspect of evolutionary theory that has required revision since Darwin's original work. Selective breeding (artificial selection) can only work with the available gene pool: it can't add new features to it. That is not to say that gene pools are permanently fixed, however: new variations can arise through mutation, but this must be clearly distinguished from the subtractive "selection" mechanism.

On pp.39--42, Dawkins talks about "biomorphs", and quite a few other terms that he puts in quote marks because they are analogies, not literal terms. These involve computer-generated drawings of various things which can resemble organisms, or organically-produced artefacts like shells. He introduces these "for the purpose of illustrating the power of artificial selection, even in an extremely over-simplified computer environment." (p.41) This may have been his primary intention, but there is another important idea presented here which warrants some attention: the distinction between "genes" and "embryology".

Dawkins here uses both terms ("genes" and "embryology") in a non-literal, analogous sense to describe aspects of his computer programs. The "genes" are a set of values which are modified randomly to generate the "offspring" of the pictures. The "embryology", on the other hand, is the fixed computer code which interprets those "genes" and converts them into pictures. In computer science terms (where I have my qualifications), the "genes" are "variables", and the "embryology" is the "algorithm". Dawkins uses different "embryologies" (algorithms) to produce different kinds of picture, e.g. one for trees, and another for shells. No amount of artificial selection is going to produce a satisfactory-looking shell if you are using the "tree" program.

It strikes me that this distinction provides an interesting insight into the limits of genetic variation -- although it's clear enough that Dawkins does not intend us to interpret his results that way. Even so, consider the dog: its genes allow for a wide amount of variation in its properties, but the underlying "embryology" (as Dawkins calls it) is essentially geared to producing dogs. No amount of selective gene-shuffling turns a dog into a cat, despite having the same basic quadruped-with-tail structure. Similarly, broccoli and cabbage have the same "embryology", because gene shuffling can get you from one form to the other, but cabbage and lettuce have a different "embryology".

Dawkins, of course, asserts that all living things are cousins, and with the right amount of mutation (not just selection), a dog could become a cat. Taken at face value, however, his computer programs tell a different story. There is variation, yes, but also a distinction between kinds of programs. He has chosen to emphasise the variation; I think it only fair to point out the equally prominent limitations of the process.

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 Post subject: Chapter 3: The Primrose Path to Macro-Evolution
PostPosted: Mon Aug 15, 2011 5:12 pm 
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Chapter three (pp.45--82) is titled, "The Primrose Path to Macro-Evolution", but it doesn't cover as much territory as the name might suggest. Macro-Evolution (being large scale change) lies beyond the end of this particular primrose path: the chapter itself only takes us from the concept of Artificial Selection to Natural Selection, via some intermediate steps. As was mentioned in the previous chapter, selection (whether artificial or natural) is a primarily subtractive mechanism, so it's only part of the evolutionary process, and can not produce macro-evolution on its own.

The first step on the path is the relationship between insects and flowers (pp.46--54). Many flowers rely on insects to carry pollen, and so insect behaviour can have a selective effect on flower breeding.

On p.47, Dawkins says, "sunflowers, like all brightly coloured flowers, owed their very existence to selective breeding by insects." He goes on to say that this is generally true of "probably all the flowers that are coloured anything other than green and whose smell is anything more than just vaguely plant-like," with the caveat that the selective agent may have been some creature other than an insect. I'm wary of this claim, since he seems to be letting one or more evolutionary assumptions enter into the discussion without making it clear that he's doing so.

The picture he's painting here makes sense if we think of it as a macro-evolutionary process in which all flowers started out green and not particularly fragrant, then underwent mutations which added various scents and colours. It would remain to provide evidence that history actually matched this hypothesis, but it seems at least possible if you grant all the necessary mutations.

If we're discussing straight selective processes, however, then all the necessary genetic variation must already be present. In the absence of selective pressures, variation would form a bell-like distribution around whatever set of traits is median for that kind of organism. It's not at all clear that the median for flowers is either "green" or "scentless" as a general rule. Indeed, it's difficult to extrapolate backwards as to what these flowering plants would have looked like in the absence of insect involvement, since they'd cease to reproduce at all without insect involvement.

I think Dawkins has got a little ahead of himself here. There is selective interaction going on here, but it's too great a stretch at this point to be claiming that insects are responsible for all fragrances and all colours other than green.

On p.49, Dawkins says, "plants have an energy economy and, as with any economy, trade-offs may favour different options under different circumstances." He calls this an important lesson in evolution, which is fair enough, but it pays to bear in mind that it's also an important lesson in engineering. What he calls a selective influence may also have been a design trade-off.

On p.50, Dawkins notes that Darwin and Wallace made certain predictions about the existence of moths which they expected to find on the basis of the existence of orchids with certain properties. Dawkins says, "this little example gives the lie, yet again, to the allegation that evolutionary science cannot be predictive because it concerns past history." Presumably the "yet again" refers to work outside this book, because this is the first such example of prediction that I have seen, but what about this prediction makes it an example of evolutionary science? Granted, the scientists in question were the first of the evolutionists, but were they applying evolutionary theory to make the prediction?

So far we've seen two definitions of "evolution". The first was, "the fact of evolution (all living things are cousins)" (p.17); the second was systematic change in gene frequency (p.33). The current example of an evolutionary prediction has no obvious relationship to either of these ideas. The basis of the prediction is the observation that moths feed off the orchid nectar, and this in turn pollinates the orchids: where we see an orchid, we expect to see a matching moth. We do not gain any additional insight from the belief that the moth and orchid are related by ancestry, nor do we need to consider the effects of changes in gene frequency to understand the moth/orchid relationship. It's not even clear that belief in the proposition "God made moths and orchids" would impact the reasoning behind the prediction. The prediction was made by evolutionists, sure, but it's not at all obvious that it was a prediction of evolutionary science.

On p.53, Dawkins says of the moths and orchids, "each side could be said to have domesticated the other, selectively breeding them to do a better job than they previously did." While it's clear that the two species share a mutually beneficial relationship, there's nothing in evidence so far to suggest that it was ever any other way. Again, Dawkins has allowed macro-evolutionary beliefs to enter into his description prematurely.

What we can say about these two species from a purely selective viewpoint is much more limited. In particular, we can say that the limits of variation in the moths will be imposed on the orchids, because even if the orchids have the genetic capacity to produce wider variations, those variations which are incompatible with the moths are not at all likely to reproduce. Humans, engaging in selective breeding, could cause these hidden traits to be expressed (just as they do with dogs) because they are not subject to the limitations imposed by the moth/orchid relationship.

On p.53 he also speaks of insects 'breeding' flowers for beauty (with 'breed' quoted to signify non-literal usage), flowers breeding the insects for pollination ability (no quotes), and insects breeding flowers for high nectar yield. Aside from the dubious personification, these statements are also problematic in that the selective process is assumed to work purely on the grounds that it is beneficial.

In particular, I don't see how the flowers are breeding the insects for pollination ability: an insect that can feed off the nectar gets its feed whether or not it also does the right thing with the pollen. Perhaps we could say that the plants are breeding themselves for pollination ability, since if they fail to get their pollen on the moth, they won't reproduce. Alternatively, we could just drop the personified causal agency altogether and observe that orchids which are good at pollination will produce more offspring than those that aren't, pretty much by definition. The selective process puts downward pressure on poor pollination techniques, but it's ludicrous to suggest that insects improved the pollination process through their selective activity. Selection requires that pollination must have been "good enough" at the very outset.

The idea that insects are breeding flowers for high nectar yield is misleading in its use of personification, and the problem is compounded by what Dawkins says next: "it is in the flowers' interests to ration their nectar." Again, the personification clouds the process rather than clarifying it: there is no active decision-making going on, nor is there any awareness of "interests". Flowers and insects don't have interests: they just have behaviour. The point is that too much or too little nectar is likely to have a detrimental effect on the flower's reproductive chances: produce too little, and the insect population will crash for lack of food (or the ones which favour some other food source will take over); produce too much, and the insects won't visit as many flowers. Insects, on the other hand, benefit only from richer food sources: any insect which is better at finding high energy food sources has more spare time and energy to devote to mating.

These selective pressures are at least what we would expect, based on common sense and knowledge of the moth/orchid relationship. As good scientists we should test the expectations against reality somehow. File that requirement away for future reference, because this chapter is only about explaining natural selection, not experimentally testing it.

Other than that, try to penetrate Dawkins' use of personification and isolate the actual raw selective pressures. Such pressures are not always precisely aligned with the metaphoric "interests" of the organism, so it's an important distinction.

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 Post subject: Re: Chapter 3: The Primrose Path to Macro-Evolution
PostPosted: Tue Aug 16, 2011 3:56 pm 
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On pp.54--55, Dawkins talks about sexual selection, or "selective breeding by females of males". The primary example given is the pheasant, but the same kind of thing happens in many other species. As before, however, I have a problem with the way that Dawkins (a) spins a macro-evolutionary tale around the phenomenon without supporting evidence, and (b) uses terms which suggest intention and purpose which actually distract from the raw selective mechanism.

The macro-evolutionary tale that he spins here is essentially the same that he told earlier, about flowers being all green and scentless until insects selectively bred them for colour and scent (p.47). In this case, the assertion is that male pheasants were once "dull brown creatures", and females selectively bred them for increased colour, until we have the colourful males we see today. There is nothing in evidence to suggest that pheasants have ever undergone such a transformation. Dawkins is getting ahead of himself again: this kind of claim should come much later in the presentation, accompanied by physical evidence. The subject in question here is sexual selection, and there are observable examples aplenty he could cite -- so why does he use a macro-evolutionary just-so story?

The other problem is that he takes as given the fact that females prefer colourful males. It's not at all clear why we should take this as given. In fact, if we suppose that the behaviour might be subject to variation, then we have a form of mutually selective influence which produces a very different outcome. To see what I mean, suppose that Dawkins is right about males being drab in the past (although possessing the necessary genetic variation for colourful plumage), but that only some females prefer colourful males. In the absence of other influences, the tendency will be for the ratio of colourful males to match the preferences of the females. Of course, if the females' preferences leave them with fewer breeding opportunities, then that will put downward pressure on hens with that preference. The presence of colour in the males also produces its own downward selective pressure in terms of increased exposure to predators. The exact outcome depends on a lot of variables, but we would expect a balance of colourful and plain males, with the ratio depending on those variables.

Of course, we don't see a balance of colourful and plain males: we see colourful males and plain females, so apparently females really are hard-wired to prefer the colourful males. The presence of such hard-wired traits is not great evidence for evolution, however, where everything must come about gradually and with natural cause. It raises a question as to how the trait came to be, and why it won't budge any more. The other curious thing about the situation is that females are uniformly drab, and males are uniformly gaudy. This means that the trait has a special property: it is carried in the chromosomes which govern gender. The association of "gender" and "colourfulness" can't be produced by selective breeding: it's a product of the way that the genes are stored. In other words, natural selection can't really explain why colourfulness is a gender-specific trait.

It strikes me that this combination of features makes decent sense from a design perspective, however. Let us take it as given that Dawkins is right about gaudy colours creating an increased exposure to predators. Aside from impressing the human audience with the display, why design males for increased risk? And why hard-wire the females with a preference for the gaudy colours so as to ensure the colours don't degenerate in the face of mutation? The species as a whole can usually afford a certain amount of loss in its males without impacting its reproductive capacity, because one male can fertilise numerous females -- although that kind of behaviour is not always a given. In any case, colourful males which manage to dodge predators despite their conspicuous plumage are clearly the right kind of stock for the survival of the species: more so than the ones that get caught, or simply blend into the environment. In other words, the genetic arrangement is designed to imbue the species with selective preferences that maintain the quality of the species.

You can probably see why it's important that the behaviour of the females be more or less hard-wired to prefer colourful males. If it were not so, then a mutation which reduced colourfulness would quite easily become established in the population, and the quality of camouflage would become a much more important survival trait in a male than speed, strength, and cunning, all of which are traits that we would want to preserve as a matter of design.

I don't expect anyone to come away from this particular argument convinced that evolution is wrong and creation is right, but I hope you can see why I'm disappointed with Dawkins' presentation of sexual selection as a mechanism, particularly as it relates to evolutionary theory.

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 Post subject: Re: Chapter 3: The Primrose Path to Macro-Evolution
PostPosted: Mon Aug 22, 2011 2:33 pm 
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On p.56, Dawkins cites the example of canaries, which have a selective interaction based on song. He says, "one could also say that females are selectively breeding males to become better and better at singing." Again, this is based on the tacit assumptions that (a) the singing was not so good in the past, and (b) that improvement can happen without limits. If we eliminate those assumptions, then it would be more accurate to say that the selective interaction serves to maintain the quality of song. As Dawkins points out, we have attained more remarkable variations in song through selective breeding, but the built-in sexual preference is sufficient to maintain the general quality of song without human intervention. We must also bear in mind that improvements can involve trade-offs in a limited budget of resources (e.g. p.49 and also later on p.69), and there may well be a point of diminishing returns in song improvement which acts as an upper bound on the selective process in nature.

On pp.56--59, Dawkins talks about a crab, Heikea japonica, which may or may not be an example of selective influence. This crab is a popular example of selection in action, but Dawkins is ultimately doubtful whether the example is legitimate. The first thing to note is that just because a plausible "just so" story can be framed around physical facts like these, it doesn't make the story true: it may just be coincidence. The other thing to note is that we don't seem to have a good way to distinguish between the "selective influence" and "mere coincidence" explanations in a case like this. Dawkins ultimately sides with the "mere coincidence" explanation, partly because of an argument that fishermen would not interact with the crabs in the required manner for selective influence, but mostly because he thinks humans are simply inclined to see faces in random patterns.

This strikes me as pretty weak science. Has nobody done an investigation of the actual practices of the fishermen? How about experimenting with selective breeding of the crabs? Why settle for all this speculation? But even if we could establish that the fishing practices and innate variability of the crabs were compatible with the "selective influence" explanation, mere compatibility is not enough to demonstrate a causal relationship, only the possibility of one. Is "gut feeling" really the best tool we can bring to bear in choosing between these explanations? That usually means deferring to one's prejudices, which is a grossly unscientific activity.

Moving on to better examples (not involving human selection), Dawkins speaks of cases where predators pass up (or just miss) prey opportunities "because of a resemblance to something sinister, and where the resemblance is certainly not due to chance." Technically, of course, it is due to chance in the evolutionary scenario, albeit chance with the additional direction of natural selection. Here again, Dawkins is going to talk about selective processes as though they were able to add useful features to the organism, despite the fact that he's already told us it's a primarily subtractive mechanism on its own. Mutation is required to provide new features, and this subject has yet to be properly introduced. It's misleading to combine the two here and present it as though natural selection is responsible for the new features.

Thus, when Dawkins talks about the caterpillar with a rear end that looks like a snake (pp.59--60), there is a tacit suggestion that natural selection is somehow responsible for the similarity. As we've seen, however, the caterpillar species must already have the genetic material which renders it capable of resembling a snake before natural selection can select it. In this case, it's not clear that there is any variation in the species with regards to this feature (no variation is mentioned), and if all members of the species have the same snake-like marking, then there is no actual selection going on within the species in that regard. Dawkins asks, rhetorically, "have bird eyes, then, been breeding insects for their resemblance to unpalatable or venomous models?" We must bear in mind that the answer is only "yes" when there is already enough variation in the species that some members will look more unpalatable or venomous than others, and it won't push the resemblance beyond those pre-existing bounds. So although there is a sense in which the answer is "yes", there is also a sense in which the answer is "no". Also, it would be nice if Dawkins would cite some experimental data which measured the effectiveness of this disguise. We can agree that it sounds like a good idea, but it's a poor substitute for actually measuring the selective advantage.

Next, Dawkins gives the example of the angler fish and its lure, suggesting that "the small prey fish are 'breeding for' more and more appealing lures". Again, Dawkins overlooks the fact that selection only works within the available genetic range, leaving the impression that indefinite improvement is possible. In this case, I also find the selective mechanism to be rather dubious. Sure, an angler fish endowed with a particularly poor lure may starve to death (p.61), or lack the food necessary to produce eggs, but once the lure is "good enough", I don't see that improvements in it offer much selective advantage. There is, after all, only so much food that one can eat, and there's no advantage in attracting more food than you can consume. It's not even clear that the lure itself plays a major role in determining the availability of food: prey needs to come within range of the lure before the lure has a chance to work, and the effectiveness of the lure is just a percentage figure describing how much of the available prey was actually attracted to it. This effectiveness can't exceed 100%, and there are diminishing returns on improvement as it nears 100%. Dawkins cites no figures or experiments which might settle this matter by measuring the selective advantage.

On p.63, Dawkins reaches the most general formulation of natural selection, which he pithily summarises as "non-random survival of randomly varying hereditary equipment." Here we must be a little cautious of the meaning of "random" in context. Strictly speaking, we would still call survival in the wild "random", because better equipment does not guarantee survival relative to one's less-equipped peers: it merely improves one's chances of survival. This is all that's needed for natural selection to work, but we should bear in mind that it works by creating a bias in a random process, not by introducing a non-random process. Similarly the "randomly varying hereditary equipment" is only "randomly varying" within the genetic bounds imposed by the parents, so there is an element of determinism in this random process, particularly in the sense that it won't add genetic features not already present in the parents.

On p.66, Dawkins makes the claim that artificial selection is the kind of experiment that one would perform in order to test the hypothesis of Natural Selection. This is an interesting claim, if it is true, because it would make Natural Selection a hypothesis which was already supported by a huge amount of experimental data at the time the hypothesis was formulated -- a hypothesis already supported by prior experimentation. Usually science happens the other way around: a hypothesis is formulated which is compatible with the known data, and then tests are performed on things implied by the hypothesis, where the outcome of the test is not yet known. I don't view this as a problem for Natural Selection -- I just think it's worth noting that a hypothesis can come either before or after a related experiment.

The bigger question here is whether Dawkins is right about selective breeding being an appropriate experiment for testing the hypothesis of Natural Selection. I've lamented the lack of experimental data supporting his various natural selection scenarios so far, and I suppose this is his answer to that objection: artificial selection provides all the confirmation we need. This is not, however, the kind of experimental support I wanted. Artificial selection definitely is relevant, and provides us with very important insights into what is and isn't possible with selective mechanisms, because the selective process can be as targeted and extreme as possible. It allows us to push selection to the limits, and it shows that variation is qualitatively possible. What we still lack is a quantitative measure of natural selection: a measurement of the selective effects of particular environmental pressures. Artificial selection can not provide this kind of information: we need experiments involving controlled environments where the actual reproductive process is left to nature. We might selectively breed the initial population for the experiment, as one of the experimental parameters, but we must then sit back and observe the effects of natural selection for a number of generations. Presumably the effects will not be as rapid as artificial selection, and will therefore take longer, but many organisms have reproductive cycles short enough to permit practical experimentation in this regard.

Evidently, Dawkins does not see it this way. He goes on to cite two more examples of artificial selection (pp.67--68) which corroborate what we already know from previous examples: namely, that traits which exhibit variation can be selectively bred to increase or decrease the trait. In relation to one of these examples -- rats and tooth decay -- he goes on to discuss the question of why the initial population of rats has relatively poor teeth compared to what can be achieved with selective breeding (pp.68--70). His main line of reasoning is "the lesson of trade-offs" (p.69), which was also mentioned in the discussion of plant pollination. This is a reasonable line of investigation, but it's a shame that he sees no reason to back the idea up with research, instead saying, "I don't know the details, but I am confident that it will be costly, and that is all I need to assume." While I agree that the concept of trade-offs is very important, knowledge of the concept does not eliminate the need for experimental data, it merely gives us a framework for understanding the data -- an idea of what to look for, and what the figures mean.

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 Post subject: Re: Chapter 3: The Primrose Path to Macro-Evolution
PostPosted: Wed Aug 24, 2011 4:17 pm 
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Now that natural selection has been fully introduced, Dawkins returns to the subject of dogs (pp.71--76). On pp.71--73 he describes a theory "most clearly articulated by Raymond Coppinger" which claims that the initial stages of dog domestication (from the wolf) were brought about by natural selection rather than selective breeding. Although plausible, it is another just-so story. The observation that dogs don't revert to wolves when left to go feral is supposed to support this theory somehow, but it's not clear to me why this is the case, particularly if the competing theory is that dogs are the result of artificial (rather than natural) selection. The difference between artificial and natural selection wouldn't necessarily result in a different outcome for feral dogs.

Dawkins goes on to cite a very interesting study by Dimitri Belyaev in which he selectively bred foxes for tameness by measuring their tolerance for human proximity (pp.73--76). After a mere six generations, they had produced some foxes they classified as "domesticated elite", which were actually eager to establish human contact (p.74). In thirty to thirty-five generations, these elites comprised seventy to eighty percent of the population (p.75). Surprisingly, the foxes also developed a number of other dog-like traits, even though the selection process considered only tolerance for human proximity (p.76). Dawkins explains that this phenomenon is called "pleiotropy" and is caused by genes having more than one effect. He emphasises its importance.

The information obtained from the fox experiment is truly fascinating, but I don't see that it supports the theory that wolves took the first steps towards becoming dogs via natural (rather than artificial) selection. After all, what we see here is that an enterprising breeder, capable of capturing and breeding wild foxes, was effectively able to breed "dogs" out of them in six generations. This despite the fact that foxes have not gone through any intermediate self-domestication via natural selection (in the manner of Coppinger's theory). Perhaps some ancient wolf-fur trader managed to capture wolves and breed them in captivity, and wound up performing a similar selective process -- breeding the wolves which were easiest to handle, and killing the others for fur -- thereby inadvertently producing the dog. I don't see why this is any less credible than the idea that it was a process of natural selection.

What's most interesting, from my perspective, is that the fox genome already contains the variation necessary for dog-like properties -- it's just been hidden all this time. This strikes me as anomalous for evolution. Dawkins wants to explain the wolf-to-dog transition in terms of long, slow, natural selection, but as I've repeatedly pointed out in my criticism of this chapter, selection of any sort can not add new features. Whether or not the wolf-to-dog transition was a product of natural or artificial selection, the genes which produce a "dog" instead of a "wolf" must have already been present at the start of the selective process. This is exactly what we see with the fox experiment: much to everyone's surprise, the foxes not only became tamer, but a "dog" emerged which had been lurking in the fox genome all along.

On pp.77-80, Dawkins returns to the subject of flowers, particularly orchids, and gives more examples of strange and fascinating relationships between these orchids and various insects. On p.80 he says, "the intimate relationship between flowers and their pollinators is a lovely example of what is called co-evolution -- evolution together." This may be his take on the matter, but he hasn't taken the opportunity to explain how the data support this assertion -- in fact, he doesn't even mention natural selection explicitly. I have a problem with this, because when I look at these weird and wonderful orchids, and their tight working relationship with particular insects, it looks a lot like they were designed for each other. In fact, if you wanted to design life and make it look conspicuously like it was an act of design, not a gradual evolutionary process, creating a lot of tight, specific inter-dependencies between species (e.g. orchids and insects) would be a good way to go about it. Well, you'd think it would, but apparently not. Suffice it to say that on the face of it, all these "intimate relationships" pose challenges for evolution to explain, and there's no explanation given at this time -- just the term "co-evolution" to describe the kind of evolution that must have happened (if it happened at all).

In closing the chapter (pp.81--82), Dawkins invites us to extrapolate the kind of change that can be wrought through selective breeding back over much longer periods, thus picturing macro-evolution. The subject of the age of the Earth is to be discussed in the next chapter, so I won't object to the time element, but as I've already pointed out, such extrapolation assumes that indefinite change is possible. This is a problem that Dawkins hasn't acknowledged yet, not even in passing as something that he will address later. Our experience with dog breeding suggests that although dogs can vary greatly, there are still limits to the variation. I have no trouble at all imagining that those limits persist no matter how long they are pushed, and there's nothing in evidence so far to challenge that expectation.

This chapter has introduced the concept of Natural Selection in full detail, but the treatment of its relationship with Evolution has been lacking. I understand that Natural Selection is one of the key mechanisms to Evolution, but Dawkins has let other mechanisms sneak into his examples without proper introduction, inappropriately leaving the impression that the example did nothing more than demonstrate the effects of Natural Selection. Selection of any sort is a subtractive process (something gets to pass on its genes, something else doesn't), and we can't extrapolate a subtractive process over long periods and expect to add new features, yet this is what he invites us to imagine. All the real-world examples of selection we've seen are subtractive, even if the results are surprising, such as finding dog-like variation within the fox genome. For evolution to occur in the sense that Dawkins presents it in his closing remarks, it must have an additive component. We already know that "mutation" is supposed to fill this role, but the evidence has yet to be presented for it as a mechanism.

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 Post subject: Chapter 4: Silence and Slow TIme
PostPosted: Sun Aug 28, 2011 3:26 pm 
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Chapter four covers the subject of measuring time via two particular mechanisms: tree rings (dendrochronology), and radioactivity (radiometric dating). Fossils are also used as an accessory to radiometric dating. Because I'm limiting my criticism to those aspects which can be addressed by an educated layman, criticism of this chapter will be relatively short. There is, no doubt, much more that an expert on these subjects could say, but I will leave such counter-arguments to the experts, dwelling instead on the deficiencies of the argument from the perspective of the intended non-expert audience. There is also a fair bit of background information in this chapter which I need not address.

The opening part of the chapter, from pp.85--88 is background information on the nature of clocks, on which I have no comment.

On pp.88--91, Dawkins introduces tree rings as a dating mechanism. I have several reservations about his argument. First, note that he claims that this mechanism is accurate "literally to the nearest year" (p.88). I expect to see some real-world examples of this accuracy, where an event with a date that is already known is dated using tree rings, and the tree ring date produces the correct result. Dawkins, however, presents no such examples. Given that there are various factors which can accelerate and retard growth (p.88), isn't it possible that a transient condition such as a local flood could temporarily accelerate growth, producing a ring in a much shorter time frame? Dawkins' assertion about the accuracy of the method seems to be based squarely on the assumption that rings are generated at the precise rate of one per year, but this assumption remains unfounded: no evidence is presented to support it, and the reader has no way to judge how true it is.

There is a similar issue with the question of matching separate wood samples to produce overlaps which allow for dating beyond the lifespan of a single tree (pp.89--90). Intuitively speaking, this seems like a pretty good approach, but I'm not happy about relying on intuition when deeper analysis is possible. Unfortunately, Dawkins does not mention anything about the statistical reliability of the matching process, which should at least be amenable to mathematical analysis. An error in matching could produce a severely inaccurate result, so it's important that we have some measure of statistical confidence in the match.

On p.90, Dawkins says that "dendrochronology in practice takes us back only about 11,500 years." This is, I understand, based on his previous assumptions about rings exactly corresponding to years. I note that the assumption would not need to be off by much -- maybe a factor of two or three -- to fit within a biblical time-scale. Even if we grant the accuracy of the assumptions for the sake of argument, trees dating back 11,500 years can hardly be considered compelling evidence either way in answering whether those trees were a product of creation or evolution: it only tells us that they had already evolved into or been created in that form at that time.

Dawkins mentions in passing some related dating mechanisms (p.90), which I also note in passing are based on similar assumptions of events being strictly annual.

The remainder of the chapter (pp.91--107) deals with radiometric dating (punctuated occasionally by snide remarks about creationists). Pages 91--96 are background information on atoms and radioactive decay, on which I have no particular comment. On p.96, a couple of important points are introduced. One is an explicitly stated assumption: the assumption that none of the daughter product (argon-40 in this case) is present in the initial conditions. The other important point is that only igneous rocks are amenable to dating in this manner.

On the subject of initial conditions, Dawkins says (p.97), "at the moment when molten rock solidifies, there is potassium-40 but no argon." I find this to be a surprising claim. If there is potassium-40 present, then it is decaying into argon-40 at the usual rate, regardless of whether the surrounding rock is solid or molten. I wouldn't expect individual atoms of argon to just bubble out of molten rock -- molten rock is pretty thick stuff, and my experience with bubbles is that their mobility is somewhat proportional to their size. When molten rock containing potassium-40 solidifies, I would therefore expect to find some argon-40 already present. This might be reduced in the case of a lava flow with a lot of exposure to the atmosphere (giving gaseous argon a chance to escape), but not so much when the rock was formed underground.

It could be that my understanding of the process is simply lacking, but it's Dawkins' job to ensure that he presents the appropriate evidence. One way to address this issue would be to take freshly solidified rock (where "freshly" is measured on the potassium-40 scale of billions of years), such as any volcanic rock produced in recorded history. It should be possible to analyse such rock and show that its argon-40 content is nearly zero (relative to its potassium-40 content). If it is, it raises the question as to where all the argon-40 went, but that's a different matter. It might also be interesting to see if there is any difference based on the type of rock: obsidian and pumice are both volcanic rocks, but the former is glassy, whereas the latter is full of bubbles. Unfortunately, Dawkins cites no such controlled tests, so we have no idea how good the assumption is.

On pp.97--101, Dawkins describes the relationship between igneous rocks and the geologic column, which is a model of the earth's sedimentary rocks based on fossils and other factors. He starts with the observation that "fossils are almost never found in igneous rock," but rather in sedimentary rocks. He mentions in passing that sedimentary rock is "gradually laid down on the floor of a sea or lake or estuary", and "the sand or mud becomes compacted over the ages and hardens as rock". Similarly, "corpses that are trapped in the mud have a chance of fossilizing." This description of rock formation and fossilisation is presented as given, which I find problematic, because it already assumes long ages and gradual processes -- which is exactly the sort of thing that this chapter is trying to prove. It's poor logical form to let a thing you are trying to prove become an assumption you make (it's called circular reasoning), so Dawkins really ought to present evidence to back it up. It's not obvious to me how one might go about that in this case: after all, if something occurs "over the ages," how does one experiment with it in a relatively fleeting human time frame? Still, the argument hasn't quite become circular yet: we may proceed with caution, bearing in mind the long-age assumptions that have been introduced.

On pp.97--98, Dawkins notes that sedimentary rocks can't be directly dated, due to their mixed composition. Instead, he suggests that the best we can do "is to use the dates of igneous rocks found near sedimentary rock, or embedded in it." There are two points to note about this. First, the problem that he cites with dating sedimentary rock has a partial loophole: we can safely assume that all the particles in a sedimentary rock were solid when the rock formed, so the date of any given particle will be older than the date of the sedimentary rock as a whole. This means that any date measurement of a sedimentary rock provides an upper limit on the age, rather than an age estimate. That's not as useful as an actual age, but it still has its uses, particularly as a cross-checking mechanism. I haven't heard of this technique being used in practice, however. Maybe it won't work -- but if that's the case, then the dating process isn't quite as simple as Dawkins has made it out to be.

The other point to note is that the argument is progressing based on the gradualist, long-age assumptions I noted earlier, bringing it closer to circularity. In order to date the sedimentary rocks on the basis of nearby igneous rocks, we must rely on gradualist assumptions: the idea that the earth has (as a general rule) been accumulating its rock layers slowly and gradually, so that things physically near each other in the rocks are close to each other in the temporal sense as well -- minus various exceptions where they aren't, for whatever reason. Dawkins' assertions about the age of sedimentary rocks is thus based at least in part on assumptions of gradualism, which in turn implies long ages, so by the time you've decided that the age of igneous and sedimentary rocks are related, you've already decided that the ones near the bottom are millions of years older than the ones near the top. To be fair, this isn't a hard and fast rule: there are possible arrangements of rock where one or the other clearly came first, and the igneous rock could therefore act as an upper or lower limit on age (if we grant that it can be dated accurately), but Dawkins is not being this conservative in his application of dating.

In discussing the geologic column, Dawkins notes the similarity of various layers around the world (p.98): "they are recognisably similar to each other, and they contain similar lists of fossils." When this is interpreted in the light of gradualism and long ages, it implies that each layer is a long period of time, and that each layer contains fossils representative of the globe during that era. Thus, Dawkins says (p.99), "long before we knew how old fossils were, we knew the order in which they were laid down, or at least the order in which the named sediments were laid down." Where one layer is physically on top of another layer, this isn't a controversial statement -- although even in those cases there may be cause to plead that the layers have been subsequently altered (p.99) -- but when rocks in one area are deemed to be older than rocks in another area due to indirect layering relationships, gradualism is a key assumption.

On p.99, Dawkins makes a pre-emptive strike against an accusation of circular reasoning: strata are identified by the fossils they contain, and the ordering of the fossils is evidence for evolution, but he says that this is not a circular argument. I agree that this is not circular, but both aspects rely on a prior assumption of gradualism and long ages. It is the relationship between gradualism and age determination which presents the danger of circularity: gradualism implies long ages, so if you reach a conclusion of long ages based on gradualist assumptions, you've merely concluded what you already assumed.

On pp.99--100, Dawkins asserts that the fossil record provides evidence for evolution on the basis that "certain kinds of fossils, for example mammals, appear only after a given date." I think that calling this "powerful evidence for evolution" is a little over the top. Aside from any other objection, it's a very superficial analysis of the data: there's a lot more to evolution than animals not appearing in the fossils before a certain date. Sure, it's one of the things that you would expect if long-age evolution were the correct explanation for the fossil record, but it's only one isolated fact. There may be a little cherry-picking going on here in the presentation of the evidence (as we will see shortly).

Another point that Dawkins makes on p.100 is that the fossil record could have been other than it is, and this leaves evolution vulnerable to falsification. "At any moment somebody might dig up a mammal in Cambrian rocks, and the theory of evolution would be instantly blown apart if they did." This is, I think, less impressive than he makes it sound: the general structure of the fossil record was known to Darwin, and he shaped his theories around it. One hardly needs to be an evolutionist to feel safe in predicting that we will never find a mammal in Cambrian rocks: we have a long history of not finding them there, regardless of any theoretical basis for the fact. Anyhow, I seriously doubt that most evolutionists -- Dawkins included -- would abandon the theory just because of one anomalous fossil.

On pp.100--101, Dawkins takes a little time out to ridicule creationism. I'm really not interested in hearing about creationism from Dawkins, because I can feel quite sure he won't present it in a flattering light. Even so, turn-about is fair play, so I'll take the opportunity to apply some of the criticism he levels at creationism against his own argument to see if it fares any better. He analyses a "head for the hills" flood theory of the fossil record and finds it wanting because he would expect to see "a statistical tailing off of mammals as you move down through the rocks," as opposed to the sudden introduction that we actually see.

If evolution (and geological gradualism) were true, we would not expect to see particularly distinct species in the fossils at all: we would expect a kind of biological continuum from bottom to top. Darwin understood this, and recognised that this is not what we find in the fossil record. He suggested that the anomaly was a product of the imperfection of the fossil record, or our incomplete study of it. These days the disconnect between the expectation and the facts has been around for so long that nobody seems to care about it any more, so perhaps I should raise a similar but distinct issue.

Less controversially, we expect to see species that exist on earth present in the fossil record during the time that they exist. We don't see mammals in Cambrian rocks, so Dawkins takes it to mean that they didn't exist then. Similarly, dinosaurs only exist in a particular range of rocks, and Dawkins takes it to mean that they evolved and then went extinct. What, then, of something like the fish called the coelacanth, which vanished from the fossil record 65 million years ago (by current evolutionary measures), but is still alive and well today? The coelacanth is not an isolated incident, either: that kind of anomaly is common enough to have its own term -- a "Lazarus taxon". Dawkins is willing to dismiss "head for the hills" flood theory on the basis of missing mammals in the Cambrian period. If that's the kind of standard we're applying, then we should reject the theory that the fossils show the history of life on earth because of "Lazarus taxa", such as missing coelacanths.

I think it's obvious that Dawkins applies different standards to different theories. We don't have to care, so long as we focus on criticising his pro-evolution argument, and don't take his anti-creation rhetoric too seriously.

On pp.103--106, Dawkins addresses the subject of carbon-14 dating. Carbon-14 is different to other radioactive isotopes used for dating in that it has a relatively short half-life, and is constantly produced from nitrogen in the upper atmosphere. There isn't much new to add here. Carbon dating has its own set of assumptions, and although Dawkins defends them as reasonable and assures us that everything has been verified as accurate, there is no evidence along the lines of taking an arbitrary bit of wood off a tree and demonstrating that it has a zero date, or such like: we just have to take Dawkins' word for it.

In closing the chapter (pp.106--107), Dawkins takes a moment to reiterate and emphasise that all the dating methods are in agreement: that "different clocks agree with each other -- within the expected margins of error." He applies the terms "confidence" and "agreement" liberally to the methods. The emphasis is necessary, he says, because of the "history-deniers" who constitute such an upsetting portion of the population. All this assertion of reliability is no substitute for actual evidence of reliability, however. The chapter has been primarily about describing the dating mechanisms rather than giving evidence of their reliability. Such background information may be a necessary part of the presentation, but the purpose it serves is to allow the audience to understand the significance of the evidence. The mechanism itself is not the evidence.

Dawkins also takes a particular swipe at history-deniers who suggest that rates of radioactive decay may have been different in the past. He calls this a glaring case of special pleading, "and it glares even more when you have to make mutually adjusted special pleading claims for each one of the clocks separately." I'd have thought it rather obvious that no such individual treatment is necessary. If the rate of radioactive decay were to be ramped up universally for whatever reason -- doubled, say -- then the clocks would still continue to agree with each other: they'd just be running twice as fast. Dawkins, however, wants us to "think of the amount of contrived and complicated fiddling with the laws of physics that would be needed in order to make all the clocks agree with each other."

I'd be more willing to take Dawkins' word for the reliability of his supporting methods if it weren't for this obvious and severe bias in his evaluation of things. This chapter has thus served largely to galvanise my scepticism and demand for independent evidence -- evidence which is sorely lacking in this chapter.

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 Post subject: Chapter 5: Before Our Very Eyes
PostPosted: Wed Sep 07, 2011 2:21 pm 
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In chapter five, Dawkins discusses a number of examples of evolution, and spits more venom at history-deniers. The examples are a mixed bag: some are controlled lab experiments, others are measurements in the wild; some involve human intervention, some don't; and a wide range of organisms are considered. The common thread is that some kind of measurable change occurs, so evolution is said to happen "before our very eyes".

Before I commence analysis of the chapter, I'd like to briefly reiterate the two definitions of evolution we've seen so far. The first was, "the fact of evolution (all living things are cousins)" (p.17); the second was systematic change in gene frequency (p.33). In this chapter, the examples of evolution will be strictly the latter kind, although some of the examples differ from what we've already seen in the book in that they involve mutation as well as selection. It's not always clear when mutation is involved and when it isn't, but we'll deal with that problem as it happens. Bear in mind also that creationists (in general) deny the so-called "fact" of evolution -- that all living things are cousins -- but not the idea that gene frequencies can change. Dawkins hasn't reconciled these two definitions of evolution yet: I gather that he considers them to be one and the same thing, but this is only the case if change can happen without limits, and we've yet to see evidence on that front.

The first example in the chapter is that of elephants and their tusks (pp.111--113). Elephants have been hunted for their ivory tusks, with hunters obviously preferring to bag the biggest set of tusks available. This hunting acts as a form of selection, putting downward pressure on tusk size (which -- I presume -- varies naturally in the population). Dawkins says (p.111), "all other things being equal, we might expect an evolutionary trend towards smaller tusks as a result of human hunting, but we'd probably expect it to take millennia to be detectable." Given the rapid results we've seen with artificial selection, why would we expect it to take millennia? I think this expectation is just born of the "long and slow" thinking that gets drummed into us as part of our basic training in evolution, and I think it's a good thing that Dawkins is undoing some of that with his examples.

Whatever the case, the actual data shows a fairly rapid and unmistakable trend towards smaller tusks (p.112). Dawkins notes that we shouldn't leap to the conclusion that it's an evolutionary change (as per definition two -- a change in gene frequency). Such a change can be a purely environmental change, for example. In this case, however, there is at least some reason to think that it is the work of selective pressures on the gene pool. It would be nice if we had some way to be sure, but all we have is the records of tusk sizes. For his part, Dawkins is "inclined to take seriously the possibility that it is a true evolutionary trend." Let's grant for the sake of argument that it is. So what, really? It seems to be an example of selection -- not exactly natural, not exactly artificial, but selection even so. We've seen quite a few examples of that already, and this one doesn't add any new considerations.

On pp.113--116, Dawkins cites the examples of the lizards of Pod Mrcaru. Five pairs of lizards were transported from Pod Kopiste to Pod Mrcaru, and the descendants of those lizards exhibited a significant dietary shift relative to their ancestors. Here, once again, is an example of rapid change: the differences in this example accumulated in thirty six years. This is one of the examples where the mechanism is not at all clear, however: there is no indication given as to why the lizards changed from primarily insectivore to primarily herbivore on the new island. Perhaps this reflects the balance of available food on the new island? We aren't told -- not even speculatively.

We also aren't told whether this kind of variation is innate to the species or not. Maybe the species is flexible enough that it has variation to suit different kinds of diets like that, and thus the genome gravitates to whatever balance suits the environment at the time by process of natural selection. That's a remarkably flexible genome if that's the case -- and it seems the most likely explanation, because the alternative is that the herbivore gut features came into existence by random mutation in that time frame. If new structural features could arise through mutation in such a short time frame, we'd be doing it in the lab on a regular basis, and we wouldn't need millions of years for large-scale evolution.

Mind you, it's not entirely clear from Dawkins' description how much change has actually taken place. Talking about the structural changes in the lizard gut, he says, "although caecal valves don't normally occur in Podarcis sicula and are rare in the family to which it belongs, those valves have actually started to evolve in the population of P. sicula on Pod Mrcaru." Started to evolve? As in only partially? Such vagueness makes analysis precarious. Still, I'd be prepared to believe that these lizards are descended from some ancestor in the same "family", taxonomically, which had fully functional caecal valves. It's possible that some of the genetic variance has been lost through selective pressures which favour insectivores, and what we're seeing here is the "as vegetarian as they get now" variation -- kind of like what you might get out of dogs if you started with chihuahuas and selectively bred them for bigness.

The vagueness of the example aside, I don't see that it presents a problem for creationism -- except perhaps a caricatured "nothing ever changes" creationism. I think it most likely that we're just seeing selection in action again -- no mutation. If it happens to be mutation in action, then that's potentially embarrassing for creation theory, but also just as potentially embarrassing for evolution -- specifically the "slow and gradual" part -- because it's so rapid, happening over a mere eighteen or nineteen generations (p.116).

On pp.116--133, Dawkins discusses a set of carefully controlled lab experiments on forty-five thousand generations of E. coli bacteria. Much of this text simply recounts the experimental process and results, and I'll assume that the reporting is fair and accurate, limiting my criticism to Dawkins' interpretation of those results. This is a significant part of the chapter, and Dawkins calls the results "distressing to creationists", so it demands a certain amount of attention to detail. Note that forty-five thousand generations would take around a million years for humans, so this experiment is somewhat comparable to a million years of human evolution (p.119). Note also that in this case there is no question that both mutation and selection are taking place.

One of the major trends seen in this experiment was an increase in the size of the bacteria. It's not clear why this is the case, but the experimental conditions (which involved a glucose-rich environment) evidently favoured the bacteria with a larger cell volume. The initial population had a cell volume of around 0.4 units, and the offspring varied from 0.6 to around 1.0 units. Most of the increase happened "in the first 2,000 or so generations" (p.123), after which it started to plateau. The differences between the experimental colonies indicate that the increases happened in different ways (via different mutations) in most cases, but colonies Ara+1 and Ara-1 had the same kinds of changes in 59 genes (p.124). Dawkins says (pp.124--125), "this is exactly the kind of thing that creationists say cannot happen, because they think it is too improbable to have happened by chance." Note that I do not trust Dawkins' reporting of creationist beliefs: he is a hostile source, and provides no citation. I'm only interested in his argument as to how the data supports evolution.

On that front, Dawkins says (p.126), "the data are at least compatible with the idea that the evolutionary change that we observe represents the stepwise accumulation of mutations." This is a relatively conservative claim, and I will grant it in part. My primary objection is that the experiment shows diminishing amounts of change over time: the data suggests migration to a new equilibrium rather than onward-and-upward progress, with further mutation producing diminishing returns. In short, the problem is that the data suggests that there are limits to the amount of mutation that can accumulate. This "evolution before our very eyes" (p.126) thus qualifies as evolution in the sense of Dawkins' second definition -- systematic change in gene frequency (p.33) -- but it still only shows E. coli becoming E. coli, so I can't agree that it lends any support to "the fact of evolution (all living things are cousins)" (p.17). There is no grounds to suppose that change of this sort could accumulate to produce, say, something other than a bacterium.

On pp.126--131, Dawkins discusses a second result of this study -- one which is an exception rather than a common trend. The Ara-3 culture underwent a significant change at around generation 33,100, resulting in its ability to use citrate as a nutrient source, which is something E. coli can't normally do when oxygen is also present (as was the case). Experiment suggests that this new ability was a compound effect of two independent mutations, neither of which was advantageous in isolation -- "like the 'irreducible complexity' of creationist propaganda" (p.128). The mutation took a very long time to appear because the probability of both mutations happening at once in the same organism are vanishingly small, and neither is under any selective pressure to become widespread. Even so, it appears that one of the necessary mutations did become widespread purely by chance in the Ara-3 culture at around generation 20,000 (p.130) -- presumably because it was present in an organism which had acquired another unrelated beneficial mutation. With the culture so "primed", the second mutation would yield its beneficial effect if it were to occur, which it did in this case at around generation 33,100.

Dawkins' conclusions in relation to this experiment (pp.130--131) are mixed, and a little confusing. He says it shows evolution in action -- which it both does and doesn't, depending on which of the two definitions of "evolution" you use, for the same reasons as in the immediately previous discussion. He says it shows "new information entering genomes" (p.131), but he hasn't defined what "new information" means in the context of a genome, and it's not possible to judge this claim without a clear indication of what it means. He also says it undermines the creationists' "central dogma of irreducible complexity". I'd let this pass as an irrelevant attack on creationism, but it seems to imply a converse: the idea that independent compound mutations are not a hindrance to evolution. This idea I consider to be in stark contradiction to the presented evidence, and a matter of some significance, so I will explain what I mean in detail.

The general idea of "irreducible complexity" is that some systems require some number N of components in order to function at all, where N is greater than one. Remove any one of the N components, and the system ceases to operate at all. This mutational advantage was an example of irreducible complexity in the sense that it involved two independent genetic mutations, and removing either of the mutations would remove all the benefit. Dawkins isn't explicit about why he considers the experiment in question to be a refutation of irreducible complexity (rather than a demonstration of it), but I surmise that the argument goes something like this: "irreducible complexity is supposed to render the mutation impossible without a designer, and this experiment demonstrates otherwise." If that were the argument, then this experiment would be a refutation of it, but I have a different understanding of irreducible complexity in the context of mathematical probability.

In the context of mathematical probability, Dawkins' model of evolution is composed of a random component -- mutation -- and a probabilistic component -- natural selection. (Artificial selection is a deterministic process, like deliberately placing a die with the six-spot facing up, whereas natural selection is a biased random process, like loaded dice which are more likely to land with the six-spot facing up.) In the case of an irreducibly complex compound mutation, selection can not provide its biasing advantage until all components of the mutation are present; the mutations themselves must arise purely by chance. It can happen in stages, as was the case in this experiment, but it is still a purely random process.

It should be immediately clear from the experimental data that a two-part irreducibly complex compound mutation of this sort is significantly less likely than any simple one-part mutation: most of the advantageous one-part mutations had happened in most of the colonies within a few thousand generations, but only one of the colonies acquired the two-part mutation in the full 45,000 generations covered by the data. There is a good mathematical reason for this: components of the advantageous mutation are unlikely to become widespread in the culture unless they are fortuitously accompanied by another mutation which provides a selective advantage. This requirement for independent simultaneous mutations makes progress significantly less likely than any single simple mutation. Even if a component of the compound mutation becomes widespread using this mechanism, it's just as likely that the mutation will be lost again in the reverse process -- mutating back the way it was in combination with some other advantageous mutation. There's no bias to drive this process in the desired direction.

For an irreducibly complex compound mutation which consists of only two independent mutations, this isn't an insuperable barrier, as we've seen experimentally, although it does retard the process immensely. The last mutation in the chain is relatively easy; the ones leading up to that point, however, decrease the probability of the compound mutation more or less exponentially. I don't intend to conduct an extensive review of the mathematics here: the problem should be relatively obvious to anyone acquainted with probability, and this is not the appropriate venue for an extensive tutorial on the subject for those that aren't. Suffice it to say that there's a good reason we only see one example of a two-part irreducibly complex compound mutation in this experiment, and a corollary of that is that we don't see any three-part (or more) irreducibly complex compound mutations. Two-part compounds are hundreds or thousands of times less likely than their single-part cousins; each additional part is likely to make the total mutation thousands of times less likely again, meaning that tens or hundreds of millions of generations would be necessary to produce an example of a three-part mutation with any probability of success. This poses a severe problem for human evolution, where a reproductive cycle on the order of twenty years doesn't leave room for hundreds of millions of generations on the currently accepted evolutionary time-scale.

My mathematical analysis of this problem has been fairly shallow, and I don't intend to make it any deeper here. Dawkins presents this evidence as though it obviously undermines the allegedly creationist "dogma of irreducible complexity". I merely wish to give a rough outline (in more detail than Dawkins, I might add) as to why I think it does the exact opposite of that. He presents this evidence as though it were a devastating blow against creationism, but it appears to me (based on the above line of reasoning) to point in exactly the opposite direction. You can judge for yourself whether or not his argument makes sense; for my part, I'm further convinced that change has practical limits, and that this constitutes evidence against the idea that all life is related by common ancestry -- unless Dawkins can present evidence of a viable chain of mostly single-step mutation between all life forms.

On pp.132--133, Dawkins briefly discusses antibiotic resistance in microbes. This is an example of both mutation and selection, similar to what has just been discussed with the E. coli experiments, only not as controlled. Once again, it is a clear-cut example of systematic change in gene frequency, but lends no particular support to the hypothesis that all life is related. Antibiotic resistance is not a recognisable step towards becoming something other than a bacterium, and the kind of mutation which produces antibiotic resistance tends to be a disadvantage when antibiotics are not present (which is why it's not a common trait in a typical environment), so the mutation could hardly be called an unqualified improvement. That same observation may also stand for the strain of E. coli that gained the ability to consume citrate: there may have been a trade-off involved which constituted a disadvantage under more typical conditions -- but we have no experimental data to answer the question.

On pp.133--139, Dawkins discusses research on guppies, conducted by Dr John Endler. The results of this research are in line with the results of other selection-oriented experiments, discussed earlier in the book. The dominant genetic traits of the population are affected by the presence of predators, the quality of camouflage, and the sexual pressures of the females that prefer conspicuously patterned males. Dawkins describes the rate of change as "staggeringly fast, by evolutionary standards" (p.139). Presumably this is because the population already contained all the necessary genetic variation, and the primary driving force behind the change was selection rather than mutation. A corollary of this is that the changes "raced ahead at a speed comparable to that achieved by artificial selection of domestic animals" (p.139). Again, this is a clear example of systematic change in gene frequency, but there is no evidence that the guppies are doing anything but vary within the usually observed range of the guppy genome, so there is no evidence here for the hypothesis that all life is related.

In the last few pages of the chapter (pp.139--141), Dawkins breaks from the main subject of the chapter to briefly discuss fossils and their living relatives. This appears to be in preparation for the next chapter, although I have not yet read it, and the title doesn't give away much. In any case, Dawkins remarks that evolution "can be both very fast -- as we have seen in this chapter -- and, under other circumstances, as we know from the fossil record, very slow." Fossils haven't been discussed in detail at this point, so I consider his claim that we "know" evolution can be slow to be a forward-looking statement at this point -- one which he will substantiate at a later time. Suffice it to say that Dawkins notes that there are fossils which bear little difference to their extant counterparts, despite being far apart on the evolutionary time-scale. He also mentions the coelacanth, which I raised as being a problematic "Lazarus taxon" in the previous chapter, so perhaps the issue will be addressed soon.

On the subject of evolution happening rapidly, I'm a little surprised that Dawkins doesn't explain some of the mechanics behind this difference in more detail, since it seems fairly clear to me based on my analysis of this chapter. If we use "systematic change in gene frequency" as our definition of evolution, then the most rapid kind of evolution happens under selective pressure when all the genes in question are already present -- a purely selective process. In this case, the speed of gene shift is limited primarily by the intensity of the selective pressure. The next most rapid kind of gene shift requires simple mutations in addition to selection. This is the primary kind of change we saw in the E. coli experiments. The speed of this process is primarily limited by the rate at which advantageous mutations occur: significant differences are observed on the scale of hundreds or thousands of generations. Slower again are the irreducibly complex compound mutations, of which we have seen only one experimental example (involving a two-part mutation). Change of this sort is extremely slow: the lone example took tens of thousands of generations to occur, and even then, it only happened in one of twelve cultures. On the basis of mathematical modelling, I would expect irreducibly complex compound mutations involving more mutations to be proportionately less likely -- and the absence of actual examples is in keeping with that expectation.

This shows different kinds of evolution which happen at different rates, but they are not all "evolution" in the sense that would allow all life to be related. In particular, the most rapid case, where mutation is not involved, is utterly inadequate in and of itself: it is bounded by the possibilities inherent in the existing genome. Mutation is obviously required in order to produce the kind of large-scale evolution implied by "the fact of evolution (all living things are cousins)" (p.17). Mutations do occur, and have visible results, but mutations involving anything more than simple isolated changes are, on the evidence presented so far, exceedingly rare. It's not clear that "the fact of evolution" can be accommodated by the accumulation of simple changes; nor is it clear that the evolutionary time scale is long enough for a significant number of irreducibly complex compound mutations to occur.

On this basis, my overall impression of the evidence so far is that the second definition of evolution -- systematic change in gene frequency (p.33) -- is a readily observable phenomenon under a wide variety of conditions. The first definition -- "the fact of evolution (all living things are cousins)" (p.17) -- is looking slightly less likely with each additional piece of relevant information.

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 Post subject: Re: Chapter 5: Before Our Very Eyes
PostPosted: Wed Sep 14, 2011 3:18 pm 
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Before I move on to the next chapter, I'd like to review briefly some earlier parts of the book in the light of chapter five. In particular I often lamented the lack of experimental data in chapter three, which discussed various kinds of selection. This chapter has been much more satisfactory in that regard, but what of Dawkins' remarks, back on p.66, that artificial selection is an appropriate experiment to test the hypothesis of natural selection?

Dawkins wrote:
If your hypothesis is that the non-random survival of random genetic variation has important evolutionary consequences, the experimental test of the hypothesis would be to have a deliberate human intervention. Go in and manipulate which variant survives and which doesn't. Go in there and choose, as a human breeder, which kinds of individuals get to reproduce. And that, of course, is artificial selection.

In response to that, I wrote the following.

TFBW wrote:
Artificial selection definitely is relevant, and provides us with very important insights into what is and isn't possible with selective mechanisms, because the selective process can be as targeted and extreme as possible. It allows us to push selection to the limits, and it shows that variation is qualitatively possible. What we still lack is a quantitative measure of natural selection: a measurement of the selective effects of particular environmental pressures. Artificial selection can not provide this kind of information: we need experiments involving controlled environments where the actual reproductive process is left to nature. We might selectively breed the initial population for the experiment, as one of the experimental parameters, but we must then sit back and observe the effects of natural selection for a number of generations.

This chapter has been full of experiments of the type I desired, and in light of that, I stand by my earlier analysis. The experiments in this chapter are clearly more supportive of natural selection as a mechanism than any experiments in artificial selection can ever be. The key difference is that reproduction was not directly manipulated: the environment was altered to see what effect it would have on the frequency of genes. These experiments clearly show that the environment can be a strong selective influence on the gene pool -- a point which artificial selection could never demonstrate on its own.

What does this do for Dawkins' case? Not a huge amount: I'm just a little bemused by the fact that he chose to volunteer artificial selection as excellent experimental support for the theory of natural selection, when this chapter is replete with far better offerings in that regard. If his point was that natural selection is a theory with good experimental support, then his point stands, but not by merit of the argument that he made for it at the time. I think that the quality of scientific evidence is best understood in relative terms, and the evidence presented in this chapter is, in my judgement, clearly better than anything in chapter three in terms of its support for the hypothesis that nature can act as a selective agent.

To put it another way, if I were suggesting changes for a second edition of his book, I would advise him to drop the argument that artificial selection provides experimental support for the theory of natural selection (on p.66), and replace it with a forward reference to chapter five, stating that it will contain much experimental support for the theory. I'd probably suggest swapping the order of chapters four and five as well -- but enough of the editorial commentary.

I grant that natural selection is well supported by the experimental data. What's still lacking at this point, of course, is evidence for the primary argument of the book: that all living things are cousins. Not to worry -- there's plenty of the book left yet.

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 Post subject: Re: Chapter 6: Missing Link? What Do You Mean, 'Missing'?
PostPosted: Tue Sep 20, 2011 12:05 pm 
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Chapter six is about fossils and the issue of "missing links", or "gaps" in the fossil record. The "gap" is the difference between what one might expect the fossil record to look like on the basis of the theory that all life is related, and the fossils which we actually find. Darwin recognised this "gap" and appealed to the imperfection of the fossil record to explain it, dedicating a whole chapter to the subject. Dawkins, on the other hand, does not really explain the nature of the problem, instead taking the opportunity to belittle creationists again. Indeed, it seems that Dawkins considers the whole issue to be a non-problem, saying "I shall emphasise in Chapters 9 and 10 that we don't need fossils in order to demonstrate that evolution is a fact." (p.145) He repeats on p.146 that the fossil record "is a bonus, something that we had no right to expect as a matter of entitlement."

Along these lines (pp.145--146), Dawkins draws an analogy with a courtroom drama in which there is already a significant pile of circumstantial and forensic evidence against the defendant. To this pile is added some security camera footage showing further evidence consistent with the prosecution's case -- but the security footage is incomplete -- there are gaps in it, including the omission of the actual murder. If we were to add another fragment of video footage between the last piece and the actual murder, then there would be two gaps -- the implication being that gaps are not indicative of a lack of evidence.

Dawkins does allow that there could be fossil evidence against evolution (pp.146--147), as he did in chapter four: the discovery of "anachronistic" fossils. I addressed this at the time it was raised in chapter four, so I won't add anything further at this point. There will be cause to revisit the issue in due course.

The chapter is off to a somewhat confusing start, and before proceeding any further, I need to take stock of the situation. Anecdotal evidence tells me that the average man in the street thinks that the fossils provide the major evidence for evolution. This certainly isn't the impression we get from Dawkins, who considers any fossil evidence "a bonus" -- the cream on top, as it were -- or from Darwin, who pleads that the fossil record must be considered highly imperfect. The evolutionist's relationship with the fossil record is thus not what most people would expect it to be: evolutionists do not consider it to be a solid historical record, but a set of arbitrary snapshots. On the one hand, they plead that it is the product of long, slow, gradual processes happening over a billion years, give or take, and on the other hand they plead that it has been interrupted for indefinite periods at arbitrary times. The fossils don't tell the right story unless you assume that one mechanism or the other is in effect at the appropriate points.

The arguments presented in this chapter must be understood in light of the above relationship, and also in the light of Dawkins' attitude that this is merely "bonus" evidence, not core to his presentation.

On pp.147--150, Dawkins addresses the "Cambrian Explosion", which is a discontinuity in the fossil record where there is a sudden proliferation of animal phyla. This is not presented as evidence for evolution, but rather as a response to the argument that this "explosion" is incompatible with evolution. Unfortunately, most of the section consists of external references to other books (plus some digression in which he accuses creationists of "quote mining" his other works), so there is not much to analyse. The one new piece of data he chooses to add at this point relates to flatworms, which have left no definitive trace in the fossil record at all. The core of the argument, which I will now quote, is given on p.149.

Dawkins wrote:
What, then, is so special about gaps in the record of those animals that do fossilize, given that the past history of the flatworms amounts to one big gap: even though the flatworms, by the creationists' own account, have been living for the same length of time? If the gap before the Cambrian Explosion is used as evidence that most animals suddenly sprang into existence in the Cambrian, exactly the same 'logic' should be used to prove that the flatworms sprang into existence yesterday. Yet this contradicts the creationist's belief that flatworms were created during the same creative week as everything else. You cannot have it both ways. This argument, at a stroke, completely destroys the creationist case that the Precambrian gap in the fossil record weakens the evidence for evolution.

This argument strikes me as unsound in several ways. For one, the argument deals with two classes of animals: the kind that have no hard parts, and are thus not amenable to fossilisation, and the kind that do have hard parts. We know that many animals of the Cambrian period were amenable to fossilisation precisely because we find fossils of them. The problem is that we don't see any prior evolutionary development of these fossils: when bony structures appear in the fossil record, they do so with great diversity and a modestly advanced stage of development. The absence of fossil traces for soft-bodied animals isn't even relevant to this observation. Dawkins may have constructed an argument with an absurd conclusion, and that argument might refute something, but it does nothing to address the problem of the Cambrian explosion.

The core fallacy in the argument is that Dawkins requires us to use the same standards for two different things: animals that do fossilise, and animals that don't. The argument requires us to treat the absence of fossils for one kind of thing as equivalent in meaning to the absence of fossils for the other kind of thing. This is clearly ridiculous: the absence of fossils for things which don't fossilise is merely consistent with their categorisation as things which do not fossilise. The existence of a fossil for such a thing would be a significant find; their absence is merely to be expected. Conversely when we do expect things to fossilise, we ascribe some significance to the absence of such fossils. Evolutionists do this all the time: Dawkins himself ascribes some significance to the absence of mammal fossils in the Cambrian period, and would consider it a refutation of Evolution if such a thing were to be found. To use Dawkins' own 'logic' against him, if we must assume that flatworms have existed throughout history despite the absence of fossils, then we should also assume that mammals existed in the Cambrian period, despite the absence of fossils. If this is not so, then perhaps we should be treating flatworms differently from vertebrates in terms of their fossil record -- and if we do that, then his argument is invalid.

This is but one of the flaws I can identify in this argument. Luckily for Dawkins, I'm really only interested in hearing his case for evolution, not his refutation of alleged creationist arguments, so this shabby argument has no direct impact on his case, and I won't bother discussing its other shortcomings.

On pp.150--151, Dawkins mentions the term "missing link" and the Piltdown Man hoax. These are side issues on which I have no particular comment. He mentions that human ancestry will be discussed in the next chapter, so I will defer analysis on that subject until then. On pp.151--155, Dawkins takes aim at some other anti-evolutionary arguments relating to transitional forms that he considers to be rubbish, and I have no particular interest in discussing their merits or the merits of his responses. On pp.155--159, under the heading, "The Pernicious Legacy of the Great Chain of Being", he gives reasons why we should not apply the concepts of "higher" and "lower" to life forms, since the terms have no precise meaning when applied to products of evolution -- at least, not to those that are contemporary with each other. This is not an argument for evolution, and requires no response on my part.

On p.159, Dawkins says, "the pernicious legacy of the Great Chain of Being also feeds the challenge 'Where are the intermediates between major animal groups?' and, nearly as discreditably, underlies the tendency of evolutionists to answer such a challenge by trotting out particular fossils such as Archaeopteryx, the celebrated 'intermediate between reptiles and birds'." There may be an element of "chain of being" thinking in the minds of some people when they pose such a question, but it hardly seems necessary. After all, there are significant morphological differences between the major animal groups -- differences which must be resolved by slow and gradual mutation if evolution is a fact. In the case of birds, for example, the most glaring issue is the evolution of feathers. Their ancestor is supposed to have been a scaly dinosaur of some sort, so we require a long, slow, gradual chain of mutational improvement (in the sense that the changes will be favoured by natural selection) from scales to feathers. It's not unreasonable to expect some fossil evidence of this transition: there is no inappropriate "chain of being" thinking behind it.

Dawkins does not address this problem: he sees the whole demand for intermediates as a fallacious offshoot of "chain of being" thinking. On pp.159--161 he spends a couple of paragraphs talking about appropriate and inappropriate classifications for things, such as whether "birds" should be considered a separate class, or just a sub-branch of "reptiles", and so on. Perhaps there is a valid argument here that it's meaningless to ask for intermediates between "reptiles" and "birds", but even if I grant that, it leaves unaddressed the much bigger and far less ambiguous question of the intermediates between scales and feathers. Even if one grants that Archaeopteryx is better described as a "feathered dinosaur" than a "bird" (given whatever it is that's supposed to divide the two), there is still no fossil evidence that scales evolved into feathers -- no transitional forms between "scale" and "feather".

In summary, Dawkins spends most of pp.150--161 telling us about what kinds of intermediates not to expect, whether it's "crocoducks" in particular (p.152), or intermediates between reptiles and birds more generally. Let us take that advice into consideration, but not waive our demand for transitional forms entirely. The long, slow, gradual change of evolution (as described in the "hairpin thought experiment" of pp.24--26) will inevitably have cause to produce intermediate forms for every biological feature in existence, no matter how unlikely that seems. It is reasonable for us to require physical evidence of these transitions, particularly in those cases where the transition seems unlikely in and of itself. The more substantial the transition, the more time we expect it to have taken, and the more reason to expect fossil evidence of it -- to the extent that fossil evidence is possible.

Speaking of fossil evidence, there has been a distinct lack of it in this chapter so far. Granted, we're only somewhere near the middle of the chapter at this point, and I'm pretty sure we're about to get to some actual examples, but it's hard not to feel a little impatient: the subtitle of this book is "the evidence for evolution", and Dawkins spent a lot of time hyping up the overwhelming nature of this evidence early on. The product is falling short of the sales pitch.

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 Post subject: Re: Chapter 6: Missing Link? What Do You Mean, 'Missing'?
PostPosted: Thu Sep 29, 2011 10:44 am 
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On pp.161--164, Dawkins talks about the evolutionary transition from sea to land-dwelling, describing the transition as obviously radical but "beautifully documented in the fossil record" (p.161). On p.162 he further discusses the classification of various things (such as whether "fish" is a proper classification), and asserts some evolutionary relationships to be closer or more distant than others, but there is no accompanying evidence at this point. On pp.163--164 he speaks of the lobefin fish, particularly the Coelacanth, which I had cause to mention earlier on. The Coelacanth is described as a "living fossil" (i.e. it's alive today and also in the ancient fossil record), but no mention is made of its "Lazarus taxon" status, which was my earlier cause for mentioning it. The lobefins are described as being our nearest evolutionary relatives among the fish, although the common ancestor did not look much like us or lungfish (p.164), and no evidence of the relationship is presented as yet.

On pp.164--169, Dawkins discusses a fossil record discontinuity called "Romer's Gap", between the fish of the Devonian period and the amphibians of the following Carboniferous period. After an introductory preamble, Dawkins introduces five fossil specimens as evidence for the evolution of fish into amphibians in this gap: Eusthenopteron, Ichthyostega, Acanthostega, Panderichthys, and Tiktaalik. These are all Devonian specimens with varying degrees of amphibian-like properties. For those following the book, note that the Tiktaalik picture is on colour page 10, pictures (b) and (c), where (c) is a model reconstruction of the fish.

While it's relatively easy to agree that these things are morphologically intermediate between typical fish and typical amphibians, it's hard to see any compelling evidence of slow, gradual evolution in them. They don't look particularly similar, and it would be a stretch to believe that any two of them were directly related in any way. They don't even look much like a progression from fish to amphibian, although this may be a product of the inconsistent ways the skeletons are illustrated -- top-down or side-on, with or without imagined flesh drawn on, and so on. I was particularly confused by the claim that Ichthyostega is more amphibian-like than Acanthostega, given that the latter seemed to have much more distinctive legs, but it then struck me that this was merely a product of the different styles of illustration. I did a little searching to see if I could get an alternative illustration, and found a better comparison of Ichthyostega and Acanthostega in Nature, which also shows the older reconstruction of Ichthyostega mentioned by Dawkins on pp.166--167.

The difference in the Ichthyostega reconstructions gives me pause to wonder how much these diagrams are products of imagination. Clearly there is some creative license involved, and presumably some of that creativity is shaped by beliefs about the creature's place in the evolutionary scheme of things. It's a pity that the evidence presented here is thus tainted to some extent by the theory it is supposed to support, but it's probably unavoidable in the context: if the photograph of the Tiktaalik fossil is anything to go by, I wouldn't have a clue what the creature looked like just on the basis of a fossil, so showing me raw fossil evidence would be nearly useless.

Even assuming that the drawings are accurate, however, this collection seems more like a jumble of interesting intermediates than an evolutionary progression. The fact that the creatures are morphologically intermediate between the archetypical fish and the archetypical amphibian doesn't automatically mean that they are evolutionary intermediates between those things. The platypus is morphologically intermediate between a beaver and a duck, but it's not an evolutionary intermediate between them. These creatures might be evolutionary intermediates, I suppose, but the evidence is far from compelling. They don't show a clear linear progression of evolution (e.g. the number of toes, p.167, Tiktaalik's unique neck, p.169), and they certainly don't show anything like slow and gradual change. Yes, I could imagine a chain of intermediates linking them, but such an exercise of the imagination is a poor substitute for hard evidence.

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 Post subject: Re: Chapter 6: Missing Link? What Do You Mean, 'Missing'?
PostPosted: Fri Nov 18, 2011 11:51 am 
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On pp.169--179, Dawkins discusses those creatures which have allegedly made the evolutionary journey from land back into the sea again, such as dugongs and whales. Pages 169--170 consist of preamble about which animals are, according to Dawkins, more or less closely related to each other, and a forward reference to chapter ten, which will discuss evidence from molecular biology. On page 171, he says that he won't be covering the fossil evidence for whale evolution in depth because it's been well presented in other recent books. Instead, he elects to reproduce one choice diagram from a book by Prothero, which illustrates a fossil timeline of supposedly related creatures including whales.

I dislike peppering my commentary with words like "allegedly" and "supposedly", but there is a certain gap between what's claimed and what's presented in evidence. Dawkins praises Prothero's conservative approach in the diagram, because he does not claim that any particular creature is the direct descendant of any other particular creature. In many cases the chronology would simply not allow it (the fossils are dated as being contemporary), but even in those cases where they are not, the points of common ancestry between them fall on thin lines, which represent extrapolations (unsupported by actual fossil evidence).

If one is to take a sceptical (rather than credulous) approach to the evidence, this absence of hard data can not be blithely overlooked. The thin-line projections in this diagram represent predictions -- testable predictions -- that creatures with some kind of intermediate morphology should be found at various points in the fossil record. A good scientific theory should have a decent success rate in terms of predictions matching outcomes. This is, after all, the technique that Dawkins says was used to find Tiktaalik (p.167). Lines drawn between fossils in this manner are nothing more than a speculative post hoc explanation (a "just so" story) unless the missing details implied by the explanation also mesh well with the facts. As it stands, these implications have either not been tested yet, or have not yet yielded positive results despite testing (we aren't told which). Either way, I'm not swayed by his suggestion that this evidence is, as presented, particularly supportive of Evolution.

If, on the other hand, we look at the thick lines, which represent actual fossil data, the most outstanding feature is the utter lack of change exhibited by Hippopotamus. According to this diagram, the hippopotamus is present and recognisable in rocks dating up to around 54 million years ago. Dawkins would probably object that time does not guarantee change, so we can not take this as evidence against Evolution, but the fact stands that this is the kind of evidence we would expect to find if evolution does not occur. It is therefore an extreme stretch to view it in the exact opposite light -- as evidence for Evolution. Are we supposed to assume that there was no environmental change in this time period to provide selective influence for evolution? Why is it that all the hard fossil evidence associated with the hippo -- evidence which spans a much larger portion of the fossil record than the other creatures mentioned here -- exhibits such a conspicuous lack of evolution?

The other thick lines tell a similar story on a smaller scale. None of them come close to the long-term lack of evolution exhibited by Hippopotamus, but each is a span of fossil findings which is readily identifiable as a single particular creature. Given that the process of Evolution is supposed to be long, slow, and gradual, I would expect to find evidence of long, slow, gradual change over time. Instead, we are presented with a collection of disconnected fossil "islands", none of which exhibits any kind of change on its own. If Evolution is true, then the slow, gradual change must have actually happened in the time between the earliest fossil of any given kind and the time at which it shared a common ancestor with another kind, but absolutely no such dynamic fossil progression is in evidence. All the actual evidence shows is stasis.

The problem here is a difference between what Dawkins presents as "an intermediate form", and what I would actually expect to see in the fossil record given the nature of Evolution as he describes it. That difference is best described in terms of continuity rather than "intermediates". If Evolution is true, then there exists a continuous sequence of parentage from every life form on the planet, back to the original living organism. Any sufficiently short segment along one of those innumerable paths will not show any change, just as any sufficiently small segment of a curve looks like a straight line, but any sufficiently large segment should exhibit a meandering, fluid morphology. The fossil record of the hippopotamus spans the entire evolution of the whale, back to before there were any sea-dwelling creatures we might call whales. This is clearly enough time for substantial change to be evident in the record, and we should see the long-term effects of evolutionary change in the hippo fossil record, even if it's not clearly evolving into anything in particular. Instead, we see stasis: an absence of evolutionary drift of any kind. In the case of the hippopotamus, Dawkins presents us with a long, straight line, and asks us to extrapolate it backwards into a meandering curve.

The outstanding feature of this diagram is that any kind of continuity in the fossil record is accompanied by stasis -- a lack of change. The change is entirely confined to the imaginary parts of the diagram: the gaps between the data. The less data there is, the more compatible it is with the evolutionary explanation: the progression of the whales leaves a lot to the imagination, but one could at least imagine evolution happening in the gaps. The record of the hippopotamus, however, leaves nothing to the imagination, and gives us unequivocal evidence of a long-term absence of evolutionary change (if we take the accompanying dating scheme as given).

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