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Our future, our universe, and other weighty topics


Saturday, February 23, 2019

Exaptation or Co-Option Does Not Fix the Incipient Stages Problem

In his book On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, Charles Darwin argued for natural selection as the main cause of the origin of species.  Darwin used the same term repeatedly to try to explain the fantastically intricate machinery of biological organisms: the word accumulate or accumulation. On page 29 of the first edition, he refers to "slight differences accumulated during many successive generations." On page 32 of the first edition of the book, he refers to  "the great effect produced by the accumulation in one direction, during successive generations." In Chapter 1 he refers to "the accumulated effects of selection." On page 410 he says, "modifications have been accumulated by the same power of natural selection." On page 471 he says, "natural selection acts solely by accumulating slight, successive, favourable variations." On page 480 he refers to "accumulation of successive slight favourable variations." On page 481 he referred to "the full effects of many slight variations, accumulated during an almost infinite number of generations."  If you were to state Darwin's explanation for biological innovations in a nutshell, it would be this: stuff piles up

But there is a huge problem with such an explanation. Accumulations are unorganized things; a thesaurus lists “pile” and “heap” as synonyms. But what we have in the human body are fantastically organized systems showing the highest order, coordination and functional coherence. It would seem to make no sense at all to speak of such systems as mere “accumulations.”


Darwin did nothing to explain how random changes could achieve any high level of organization, let alone the gigantic degree of  organization we see in the human body. Neither Darwin nor any Darwinist has ever explained how natural selection and random changes could ever cause biological parts to become well  organized.  There is no good evidence that any complex visible biological innovation ever appeared because of random mutations and natural selection, and such an idea is essentially an article of faith in a modern-day secular creed. 

In Chapter 7 of  the sixth edition of On the Origin of Species, which you can read here, Darwin addresses various objections to his theory. On page 170 he states, “A much more serious objection has been urged by Bronn, and recently by Broca, namely, that many characters appear to be of no service whatsoever to their possessors, and therefore cannot have been influenced through natural selection.” Darwin concedes on the next page that “there is much force to the above objection.” We can state the objection like this: many types of plant and animal species, in particular mankind, have major characteristics that do not add to their survival value, and which therefore cannot have arisen because of natural selection (which Darwin tells us works only to improve survival value or the likelihood of reproduction). In many types of plants (in particular, flowers) we see a vast host of features which rather seem to exist according to some principle of diversity or ornamentation or beauty rather than some principle of biological functionality. Using the term “the biology of the baroque,” biologist Michael Denton has pointed out many examples of non-adaptive features in biological organisms: things such as the intricate shapes of maple leaves, the huge variety of colors in butterfly wings, and peacock feathers.

In humanity we see many mental abilities and characteristics that seem to have no survival value for any organism existing in the wild, including spirituality, artistic creativity, philosophical reasoning ability, and mathematical ability. See here for a full discussion of such traits, and how they cannot be explained by natural selection. The co-founder of the theory of evolution by natural selection (Alfred Russel Wallace) wrote an essay stating that the theory could not explain some of the most important mental characteristics of mankind. 

On page 177 of the sixth edition of On the Origin of Species, Darwin discusses another objection to his theory, saying, “The one new point which appears to have struck many readers is, 'that natural selection is incompetent to account for the incipient stages of useful structures.'” This is the gravest objection to the credibility of Darwin's explanation for biological complexity. 

In general Darwinism fails to explain the first stages of useful structures. This was pointed out very clearly in Darwin's time by the biologist Mivart, who wrote the following at the beginning of Chapter II of his book On the Genesis of Species: "Natural Selection utterly fails to account for the conservation and development of the minute and rudimentary beginnings, the slight and infinitesimal commencements of structures, however useful those structures may later become." Mivart devoted Chapter II of that book to many examples of "incipient stages" that Darwinism could not explain well.  You can read online Mivart's many examples here.  Without even reading that, it is easy to think of many examples of incipient stages that would not be useful, such as the first small part of any limb (such as an arm or leg) or the first small part of a wing or the first small part of a mammary gland. Other examples are the first small part of a penis, testicle, or an ovary.  On the microscopic level, there is the fact that the first small part of almost every protein molecule is useless. 

To try to defend against the objection that natural selection cannot account for the incipient states or early stages of an innovation, Darwin appealed to an idea that is now called co-option or exaptation. It is the idea that a biological innovation can arise when evolution takes advantage of something that had arisen for some other purpose, and uses it for a different purpose. 

For example, on page 189 of the sixth edition of On the Origin of Species,  Darwin pointed out that Mivart had complained that in their earliest stages, mammary glands would not have been useful for providing milk for an infant:

Mr. Mirvart asks: “It is conceivable that the young of any animal was ever saved from destruction by accidentally sucking a drop of scarcely nutritious fluid from an accidentally hypertropied cutaneous gland of its mother? And even if one ever was so, what was the chance of the perpetuation of such a variation?” But the case is not here put fairly. It is admitted by most evolutionists that mammals are descended from a marsupial form; and if so, the mammary glands will have first been at first developed within the marsupial sack.

Here Darwin was trying to use the idea of co-option, arguing that the mammary glands in the breasts of mammals weren't too hard to develop, because they were co-opted from glands in a pouch-like structure of marsupials from which mammals are descended. But today's evolutionary biologists do not maintain that mammals are descended from marsupials. So this example by Darwin of a co-option now must be dismissed as erroneous reasoning.

Darwin also tried to use the swimbladder of fishes as an example of co-option, implying that lungs were not too hard to develop, because they developed from an earlier organ that existed for a different purpose, for the purpose of helping some fish float. On page 147-148 of the sixth edition of On the Origin of Species,  Darwin argued as followed:

The illustration of the swimbladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one purpose, namely, flotation, may be converted into one for a widely different purpose, namely respiration....All physiologists admit that the swimbladder is homologous or “ideally similar” in position and structure with the lungs of the higher vertebrate animals; hence there is no reason to doubt that the swimbladder has actually been converted into lungs, or an organ used exclusively for respiration.

But this example of co-option or exaptation must also be placed in the trash can. This is because modern evolutionary biologists tell us that the first swim bladders appeared after the first lungs appeared, not before them. The Wikipedia article on swim bladders tells us, “Darwin reasoned that the lung in air-breathing vertebrates had derived from a more primitive swim bladder, but scientists now believe that the swim bladder derived from a more primitive lung.”

Other supposed cases of co-option or exaptation are not much better than these cases. It is claimed that eyes evolved from organs derived for a different purpose, the purpose of telling light from dark. But this is not real co-option, because there would be no difference between the most primitive type of vision and the ability to tell light from dark. Place a few sheets of paper in front of your eyes, and you have something that is both the weakest type of vision and something allowing you to tell light from dark.

All claims of exaptation are co-option on a large visible scale are speculative. We have no proof at all that any single complex biological innovation evolved from any previous biological structure that served some different purpose. When scientists speculate that flying feathers arose from feathers that appeared for the purpose of attracting mates or keeping warm, they are just engaging in wild guesses that don't sound credible. Even if such claims were true, they would have little force, since the origin of, say, a seductively attractive feather would be as hard-to-explain (from random mutations) as the origin of a feather for flying. 

It seems, in fact, that a Darwinist will be hard-pressed to produce a single credible major case of co-option, in which evolution could have conveniently converted one system or organ created for one purpose, and used it for some other purpose. This should surprise no one. It is, in fact, extremely rare for you to have a situation where a complex object existing for one purpose can be conveniently converted to serve some entirely different purpose. Examples of co-option are few and far-between. There is a simple reason why this is so. In the great majority of cases, once some object (whether biological or inorganic) has been specialized to serve some particular purpose, it then becomes so specialized that it is no longer possible to easily adapt it to serve some very different purpose.

Looking around my humble living quarters, I see the following objects: some beds, some chairs, a sofa, an alarm clock, a fan, some book shelves, a television, a cable box, some computers, a bicycle-type exercise machine, two tables, some pots and pans, an oven, a refrigerator, a dental irrigation device, some cell phones, some cameras, a video game console, a video game controller, a flashlight, a hammer, an air conditioner, and an air filter. Thinking about all of these things, I can find no case in which any one of them could have been built from a simpler invention which originated to serve some different purpose. Also I cannot think of a single way in which I could extend or slightly modify any of these objects so that they could serve a different purpose.

If parts or objects are specifically designed to be re-usable and to be “building blocks,” then you might be able to use them for many different purposes (Lego blocks are an example). But if something functional is complex, and has not been specifically designed to be re-usable and to be a kind of building block, it will tend to be so specialized that it cannot be used for different purposes other than the special purpose for which it originally existed. Co-option or exaptation (in which evolution achieves some new purpose by using something “on the shelf” which originated for some other purpose) is something that we would not expect to happen other than very, very rarely.

A simple example can show why appealing to co-option or exaptation is not an effective defense against claims that natural selection and random mutations could not produce very complex functional structures. Let's say a person argues that it is too unlikely that a log cabin would ever form in the woods by a random falling of logs. You might try to defend against that claim by arguing that it wouldn't be too hard, because an accidentally-forming log cabin might form from the much simpler structure called a lean-to, and that would be easier. But this reasoning is fallacious. The overall probability of falling logs forming first into a lean-to and then later into a full log cabin would not be any greater than the probability of the log cabin forming from falling logs in a way in which no lean-to existed while the log cabin was forming. Similarly if it would require five lucky random mutations to achieve some biological structure serving one purpose, and then five other lucky random mutations for that structure to be converted to serve some different purpose (call it the second purpose), then overall achieving this second purpose would not be much more likely than it would be if no such conversion occurred, and you needed ten random mutations to achieve the structure serving the second purpose.

I can explain another general reason why the idea of co-option or exaptation does not work in overcoming the problem that natural selection cannot explain the incipient stages of complex innovations. The reason is that in almost all cases in which we can imagine one complex biological innovation (used for one purpose) changing into some other biological innovation (used for some other purpose), there would be a loss of functionality before there was an equally great gain of functionality; and such a thing would be forbidden under Darwinian assumptions.

In almost all cases in which we can imagine some biological thing gradually evolving from one function to another, there would be an intermediate stage involving a decline in functionality. For example, if some species with arms were to evolve so that the arms became wings, that would be an example of co-option or exaptation. But there would inevitably be an intermediate stage in which these arms-becoming-wings were less useful as arms, but not yet useful as wings. Such a state would involve an intermediate loss in overall function.

Why does this reality discredit the idea of exaptation as a widespread occurrence in biology? According to Darwinian principles, evolution or natural selection should never move some biological innovation from one functional state to a less functional state. That's because once the transition was made to a less functional state, the organism would be less likely to survive; and organisms in such a state would become less and less common in the population. If evolution had precognition, and could foretell the future, there would be no problem with imagining a scenario where some organ or appendage (gradually changing over thousands or millions of years) goes from being functional for reason X, to then being less functional, and then to being functional for reason Y. But since evolution or natural selection lacks any ability to foretell the future, such transitions should not occur under Darwinian assumptions.

The site https://www.biorxiv.org is a server for preprints of biology papers. It stores preprints for very many thousands of biology papers (for example, when I searched for articles with "liver" in the title, I got 105 matches). Using the “Advanced search” feature of this site, I searched for biology papers with “exaptation” in the title. There was only one paper found. When I searched for papers with “co-option” or “cooption” in the title -- a term synonymous with “exaptation” – I found only seven papers. All of these papers (which are highly speculative)  refer only to claims of a co-option or exaptation on a microscropic level, typically one particular molecule or microorganism or gene.  None of these papers claim to have found evidence for exaptation involving a visible structure. Evidently our biologists have actually been able to find very few substantive examples of exaptation, which shows that the idea of exaptation is only a very weak and inadequate defense against the objection that Darwinism cannot explain the beginning or incipient stages of complex biological structures.

In almost all cases that we can imagine an incipient or beginning stage of a complex biological innovation, it is not true that we can find some other purpose that such a thing would have served.  For example, no purpose would be served by one tenth of a vision system, one tenth of a circulatory system, one tenth of a reproductive system, one tenth of a digestive system, or one tenth of an arm or leg. In the rare cases in which a use can be found for a small fraction of a biological innovation, the incipient stages problem has still not been beat, because that fraction can always be halved, and almost always no use will be found for that smaller fraction.  Show me a rare case where one fifth of some biological innovation is useful, and it will probably be a case where one tenth of such a biological innovation could not have been useful; and  show me a rare case where one tenth of some biological innovation is useful, and it will probably be a case where one twentieth of such a biological innovation could not have been useful.

On the lowest useful level, organisms are made from protein molecules, and an average protein molecule in a human consists of about 500 amino acids arranged in just the right way to achieve a functional result. In almost all cases, there is a situation where a particular specialized protein molecule is useless if only half of the molecule exists or only a third of the molecule exists (partially because protein folding, required for proper protein function, is a very tricky thing to get right).  Here the incipient stages problem exists to a mountainous degree, and the idea of exaptation is all but useless in lessening such a problem. Our biologists have no credible accounts of the origin of any of the more complex protein molecules, and they try to talk about such a topic as little as they can. This difficulty was unknown to Darwin, who had no idea that humans were built from 20,000 different types of fine-tuned protein molecules that would be so hard to explain, each one of these an impressive biological innovation.

Our biologists tell us that random mutations and natural selection (the mere fact that fit organisms reproduce more) are sufficient to explain how blind nature was able to leap to stratospheric heights of biological organization and functional coherence. Similarly, a man might tell you that his herbal supplements and excellent athletic shoes can allow him to jump to the top of a cloud. When someone objects that natural selection and random mutations would never be remotely sufficient to cause the appearance of biological organisms more organized and complex than a 747 jet, our biologists say it's not too hard for such towering zeniths of biological organization to be reached, because leaps can be made from simpler things which existed for other purposes (the idea of exaptation or co-option).  And similarly, the man with the excellent athletic shoes might tell you it's not too hard for him to jump to the top of a cloud, because rather than jumping all the way from the sidewalk, he can jump from the top of his roof. 

What is very amusing in that each time a person tries to use the idea of exaptation to defend Darwinian explanations, he is twice appealing to purpose while trying to salvage a theory of purposeless biological origins.  This is because the idea of exaptation or co-option is typically stated as the idea that some biological structure that existed for one purpose was then used by evolution for some other purpose.  When someone  uses such "double purpose" reasoning to defend a theory of purposeless biological origins, he is rather like a husband who swears to his wife that he has given up drinking, and then proposes that he and his wife drink a toast to his new sobriety -- not just a vodka toast but a good stiff whiskey toast also. 

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