email - June 2010

Darwinís Eye Quote

Creationists and evolutionists disagree over what Darwin said about the evolution of the eye. Letís try to straighten it out.

S. P. wrote.

Hi there R. David,

In one of your essays you wrote: "Darwin considered the eye to be serious biological evidence against evolution." which means that you are either ignorant of what Darwin actually thought or you are being purposefully decpetive [sic].

Darwin actually wrote:

"To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of Spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree. When it was first said that the sun stood still and the world turned round, the common sense of mankind declared the doctrine false; but the old saying of Vox populi, vox Dei ["the voice of the people = the voice of God "], as every philosopher knows, cannot be trusted in science. Reason tells me, that if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certain the case; if further, the eye ever varies and the variations be inherited, as is likewise certainly the case; and if such variations should be useful to any animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, should not be considered as subversive of the theory."

So, which is it?† Ignorance or a desire to deceive that drives you?

Our quote, which he took out of context, came from our response to an email in November, 2002. Hereís the quote in context.

Jordan has "yet to hear of a single case of hard biological evidence rejecting evolution." We wonder what his criteria for hard biological evidence are. Darwin considered the eye to be serious biological evidence against evolution. 1

We simply noted that Darwin considered the evolution of the eye to be troublesome. It was troublesome enough that he devoted quite a long discussion of it in Chapter 6 of the Origin of Species.

Some creationists take what Darwin said out of context to make it appear that Darwin never solved the eye problem to his own satisfaction; but Darwin did finally figure out a way to rationalize away his doubts, as we will see when we quote the entire chapter later. That does not change the fact that, "Darwin considered the eye to be serious biological evidence against evolution." If he didnít consider it to be a serious problem, he would not have dealt with it.

Of course, whether or not Darwin believed it was possible for the eye to evolve from scratch through natural selection is irrelevant. Just because Darwin did or did not believe something doesnít make it true or false. What is relevant is that Darwin realized the problem, explained the problem, and attempted to find a solution to the problem. It is up to you to decide if Darwinís solution is adequate or not. You, however, have the advantage of more than 150 years of science that Darwin didnít have.

Quote Mining

Creationists love to quote Darwin as saying, ďthat the eye could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.Ē They usually follow it up with, ďIf it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.Ē

Evolutionists cry foul, claming that this is unfair ďquote mining.Ē They might have a point. These little sound bites do make it appear that Darwin disbelieved his own theory, which simply isnít true.

The Truth

The truth is that Darwin brought up many significant difficulties with his theory, and made an honest attempt to answer those difficulties. We believe he failed to adequately answer them; but what we believe doesnít matter. What you believe is the only thing that counts.

There were several editions of Origin of Species. The one that TalkOrigins chose for their website is the first edition. Since TalkOrigins is an anti-creationist website, we will use the same edition they did. It is slightly different from what S.P. quoted in his email, but the difference isnít significant.

It is a very long chapter, and is difficult to read. So, we will explain it, paragraph by paragraph. We have left nothing out. We will just paraphrased each paragraph after quoting it. It is, of course, up to you to determine if we have paraphrased it accurately. Thatís why we are including Darwinís entire (boring) text.

Organs of extreme perfection and complication. To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound. 2

Hereís our paraphrase:

The Problem of Complex organs. When you consider the complexity of the eye, it seems impossible that it could have arisen by natural selection. But, if one can imagine a sequence of small steps which leads to up to a modern eye, then that sequence of steps shows that it is possible to believe that it could have happened.

In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted from the earlier stages of descent, in an unaltered or little altered condition. Amongst existing Vertebrata, we find but a small amount of gradation in the structure of the eye, and from fossil species we can learn nothing on this head. In this great class we should probably have to descend far beneath the lowest known fossiliferous stratum to discover the earlier stages, by which the eye has been perfected. 2

It would be nice if we could find in the fossil record a series of fossils showing how the eye evolved step by step; but we canít find that in the fossil record. So, we have to look at living things, some of which are presumably more highly evolved than others. Unfortunately, there isnít much to go on here, either.

In the Articulata we can commence a series with an optic nerve merely coated with pigment, and without any other mechanism; and from this low stage, numerous gradations of structure, branching off in two fundamentally different lines, can be shown to exist, until we reach a moderately high stage of perfection. In certain crustaceans, for instance, there is a double cornea, the inner one divided into facets, within each of which there is a lens shaped swelling. In other crustaceans the transparent cones which are coated by pigment, and which properly act only by excluding lateral pencils of light, are convex at their upper ends and must act by convergence; and at their lower ends there seems to be an imperfect vitreous substance. With these facts, here far too briefly and imperfectly given, which show that there is much graduated diversity in the eyes of living crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class. 2

If we look at crustaceans (lobsters and crabs), we do see that they have very different eyes. Since lobsters and crabs evolved from a common ancestor, and their eyes are so different, natural selection must have made them different. Since natural selection is powerful enough to make these large differences near the end of the evolutionary process, it must have been powerful enough to do the whole job. That is, it must have been powerful enough to turn a single light-sensing cell into a full-blown eye. [Remember, these are Darwinís ideas, not ours. We are just paraphrasing him.]

He who will go thus far, if he find on finishing this treatise that large bodies of facts, otherwise inexplicable, can be explained by the theory of descent, ought not to hesitate to go further, and to admit that a structure even as perfect as the eye of an eagle might be formed by natural selection, although in this case he does not know any of the transitional grades. His reason ought to conquer his imagination; though I have felt the difficulty far too keenly to be surprised at any degree of hesitation in extending the principle of natural selection to such startling lengths. 2

If one is willing to believe that lobster and crabs evolved such different kinds of eyes, it is easy to take the next leap of faith that eagle eyes evolved, too.

It is scarcely possible to avoid comparing the eye to a telescope. We know that this instrument has been perfected by the long-continued efforts of the highest human intellects; and we naturally infer that the eye has been formed by a somewhat analogous process. But may not this inference be presumptuous? Have we any right to assume that the Creator works by intellectual powers like those of man? If we must compare the eye to an optical instrument, we ought in imagination to take a thick layer of transparent tissue, with a nerve sensitive to light beneath, and then suppose every part of this layer to be continually changing slowly in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further we must suppose that there is a power always intently watching each slight accidental alteration in the transparent layers; and carefully selecting each alteration which, under varied circumstances, may in any way, or in any degree, tend to produce a distincter image. We must suppose each new state of the instrument to be multiplied by the million; and each to be preserved till a better be produced, and then the old ones to be destroyed. In living bodies, variation will cause the slight alterations, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. Let this process go on for millions on millions of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man? 2

One canít help comparing the eye to a telescope. A telescope is the product of an intelligent designer. If we presume that the eye is the product of an intelligent designer, namely the God of Abraham, then we have to make some possibly presumptuous assumption about His design process. It just might be that God created the eye through natural selection over many millions of years.

If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, round which, according to my theory, there has been much extinction. Or again, if we look to an organ common to all the members of a large class, for in this latter case the organ must have been first formed at an extremely remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has passed, we should have to look to very ancient ancestral forms, long since become extinct. 2

If we could find just one organ, such as the eye, which could not possibly have been formed by a sequence of functional predecessors, then my theory will be disproved. There are lots of organs for which we have no explanation for how they came about in such a step-by-step fashion. But just because we donít know the explanation, that doesnít mean there isnít one. Many different creatures have similar organs; therefore, the first instances of those organs must have evolved very long ago, and were modified slightly by many small steps. If we had a better fossil record, we could probably find what those steps were.

We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; thus the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might easily specialise, if any advantage were thus gained, a part or organ, which had performed two functions, for one function alone, and thus wholly change its nature by insensible steps. Two distinct organs sometimes perform simultaneously the same function in the same individual; to give one instance, there are fish with gills or branchiae that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ having a ductus pneumaticus for its supply, and being divided by highly vascular partitions. In these cases, one of the two organs might with ease be modified and perfected so as to perform all the work by itself, being aided during the process of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be quite obliterated. 2

Just because we donít know how it happened, we should not jump to the conclusion that it didnít happen. Maybe a stomach turned inside out and became a lung. It could happen!

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 wholly different purpose, namely respiration. The swimbladder has, also, been worked in as an accessory to the auditory organs of certain fish, or, for I do not know which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder. 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 seems to me to be no great difficulty in believing that natural selection has actually converted a swimbladder into a lung, or organ used exclusively for respiration. 2

But maybe the lung didnít evolve from the stomach. Maybe it evolved from a flotation bladder in a fish. Or, maybe the bladder evolved into an ear. I donít know; but I have no great difficulty believing it.

I can, indeed, hardly doubt that all vertebrate animals having true lungs have descended by ordinary generation from an ancient prototype, of which we know nothing, furnished with a floating apparatus or swimbladder. We can thus, as I infer from Professor Owen's interesting description of these parts, understand the strange fact that every particle of food and drink which we swallow has to pass over the orifice of the trachea, with some risk of falling into the lungs, notwithstanding the beautiful contrivance by which the glottis is closed. In the higher Vertebrata the branchiae have wholly disappeared the slits on the sides of the neck and the loop-like course of the arteries still marking in the embryo their former position. But it is conceivable that the now utterly lost branchiae might have been gradually worked in by natural selection for some quite distinct purpose: in the same manner as, on the view entertained by some naturalists that the branchiae and dorsal scales of Annelids are homologous with the wings and wing-covers of insects, it is probable that organs which at a very ancient period served for respiration have been actually converted into organs of flight. 2

We just donít know, because we donít have fossils. If we did have the fossils, we would know how one tube serves as both wind pipe and food pipe, with food and drink rarely getting into the lungs. Insects breathe through their skin. Somehow those breathing scales probably turned into wings. Gee, I wish we had some fossil proof!

In considering transitions of organs, it is so important to bear in mind the probability of conversion from one function to another, that I will give one more instance. Pedunculated cirripedes have two minute folds of skin, called by me the ovigerous frena, which serve, through the means of a sticky secretion, to retain the eggs until they are hatched within the sack. These cirripedes have no branchiae, the whole surface of the body and sack, including the small frena, serving for respiration. The Balanidae or sessile cirripedes, on the other hand, have no ovigerous frena, the eggs lying loose at the bottom of the sack, in the well-enclosed shell; but they have large folded branchiae. Now I think no one will dispute that the ovigerous frena in the one family are strictly homologous with the branchiae of the other family; indeed, they graduate into each other. Therefore I do not doubt that little folds of skin, which originally served as ovigerous frena, but which, likewise, very slightly aided the act of respiration, have been gradually converted by natural selection into branchiae, simply through an increase in their size and the obliteration of their adhesive glands. If all pedunculated cirripedes had become extinct, and they have already suffered far more extinction than have sessile cirripedes, who would ever have imagined that the branchiae in this latter family had originally existed as organs for preventing the ova from being washed out of the sack? 2

If all pedunculated cirripedes had become extinct, and we didnít have any fossils of them, we would not have any idea how egg sacks evolved.

Although we must be extremely cautious in concluding that any organ could not possibly have been produced by successive transitional gradations, yet, undoubtedly, grave cases of difficulty occur, some of which will be discussed in my future work. 2

I donít want to admit that there are any organs which could not have evolved step-by-step; but there sure are a lot of them that are hard to explain! Rest assured, I will explain them all, someday.

One of the gravest is that of neuter insects, which are often very differently constructed from either the males or fertile females; but this case will be treated of in the next chapter. The electric organs of fishes offer another case of special difficulty; it is impossible to conceive by what steps these wondrous organs have been produced; but, as Owen and others have remarked, their intimate structure closely resembles that of common muscle; and as it has lately been shown that Rays have an organ closely analogous to the electric apparatus, and yet do not, as Matteuchi asserts, discharge any electricity, we must own that we are far too ignorant to argue that no transition of any kind is possible. 2

Neuter insects and electric eels sure have me stumped.

The electric organs offer another and even more serious difficulty; for they occur in only about a dozen fishes, of which several are widely remote in their affinities. Generally when the same organ appears in several members of the same class, especially if in members having very different habits of life, we may attribute its presence to inheritance from a common ancestor; and its absence in some of the members to its loss through disuse or natural selection. But if the electric organs had been inherited from one ancient progenitor thus provided, we might have expected that all electric fishes would have been specially related to each other. Nor does geology at all lead to the belief that formerly most fishes had electric organs, which most of their modified descendants have lost. The presence of luminous organs in a few insects, belonging to different families and orders, offers a parallel case of difficulty. Other cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with a sticky gland at the end, is the same in Orchis and Asclepias, genera almost as remote as possible amongst flowering plants. In all these cases of two very distinct species furnished with apparently the same anomalous organ, it should be observed that, although the general appearance and function of the organ may be the same, yet some fundamental difference can generally be detected. I am inclined to believe that in nearly the same way as two men have sometimes independently hit on the very same invention, so natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly the same manner two parts in two organic beings, which owe but little of their structure in common to inheritance from the same ancestor. 2

There are only a few kinds of electric fish, and they arenít very similar at all. The general rule is that if very different species of the same species have a common trait, but most of the members of that family donít have that trait, it must be the case that the common ancestor had the trait, and most of the descendants lost it. But being able to electrocute prey is such an obvious advantage, it beats me why so many fish lost it. And there are other puzzling cases, like distantly-related glowing insects, and unique pollen structures on some distantly-related plants. All I can figure is that the same function evolved independently.

Although in many cases it is most difficult to conjecture by what transitions an organ could have arrived at its present state; yet, considering that the proportion of living and known forms to the extinct and unknown is very small, I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. The truth of this remark is indeed shown by that old canon in natural history of 'Natura non facit saltum.' We meet with this admission in the writings of almost every experienced naturalist; or, as Milne Edwards has well expressed it, nature is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should this be so? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so invariably linked together by graduated steps? Why should not Nature have taken a leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps. 2

In many (but not all) cases, we can invent some story about how it came to be by some step-by-step process. So it seems that ďNature doesnít make any jumps.Ē Now we know why. Natural selection depends on small, gradual changes. God would have done it differently. He would have made big jumps, not small steps.

Two Reasons Darwin Isnít Read

We sometimes joke that the Origin of Species is just like the Bible because (1) it is a book that some people base their whole life upon, (2) everybody knows what it says, and (3) few people have actually read it. We bet you have never read the chapter we just quoted for you.

There are two reasons why few people have actually read Origin of Species. The first (as you have just discovered) is that Darwin was a very bad writer. It takes a lot of effort to make sense of what he says.

The second reason is that once you do figure out what he is trying to say, and put it in plain English, it isnít as compelling as evolutionists would like you to believe. In fact, it smacks of foolishness.

Thatís why evolutionists want to censor the science curriculum, telling only the evolutionary side. And, they donít even really want to tell you much about evolution. They just want to say, ďEvolution is a fact, not a theory!Ē and let it go at that. They will tell you to trust the expert because evolution is too complicated for someone like you to understand. But it isnít too complicated for you to understand. If you are given a chance, we are sure you can tell fact from fiction. Donít you think you deserve a chance to hear both sides and make up your mind?

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Footnotes:

1 Disclosure, November 2002, ďDisgruntled Engineers Against EvolutionĒ, http://www.scienceagainstevolution.org/v7i2e1.htm
2 Darwin, Origin of Species, Chapter 6, http://www.talkorigins.org/faqs/origin/chapter6.html