Barbarian on the imperfection of vertebrate vision:
A spot in the visual field where one cannot see? I don't see the advantage.
Yep. That's the defect. You see in other kinds of eyes, such as those of
cephalopods, the eye isn't wired backwards, and there is no blind spot.
This is a very interesting point. Firstly, the eye is wired backwards in vertebrates for good reason even aside from metabolic needs. Cephalopods are water creatures, they need only see in water. Due to the fact they see in water, they are unable to see great distances and thus have no need in resolving objects that are a long distance away. Simple high-school grade optics, will show you that the "wired-backwards" design cuts down on optical image interference when resolving objects at long distances.
There are ways to produce good distance resolution without introducing a defect. Lens makers have known how to do this for hundreds of years. I have an interest in old cameras and optical performance. What do you mean by "optical image interference?"
Thus both vertebrate eyes and cephalopod eyes show good design.
Well no. A designer would simply have used a better receptor cell, eleminating the need for a reversed retina, and thus removing the blind spot. There are other defects, all of them noticable in terms of the way they evolved.
Secondly, the blind spot cannot be said to be a defect. Firstly it allows an increased blood flow to the complex retina and other working parts of the eye needful of this supply.
That's the cause of the defect. But the fact that one has to have a defect because the arrangement is faulty, does not mean that it doesn't exist.
And secondly, we have too little understanding of how the brain interpets what it gets from the eye. It maybe that the brain uses the blind-spots in the eyes as static reference points as part of a mechanism to quickly align the eyes when moving rapidly from one object to the next at various distances (It may not be, but the point is, we don't know).
Maybe the magic toad inserts information to cover it. But the evidence shows that it's a defect.
Barbarian observes:
This is called "confabulation". Your brain, lacking evidence about what is in that area, makes up information to compensate. It's not a problem, unless there happens to be something there that you need to know about.
There would most likely only be a problem if you had one eye closed, and(/or if it's out of the field of vision of one of the eyes) the object suddenly appeared at a distance of about 12 inches from your face!
Fast moving objects, in the blind spot are known to hit before one has adequate warning.
Furthermore since the right eye can see whatever lies in the left eye's blind spot and vice versa, the two eyes together provide complete vision. Perfect.... definitely looks like design to me!
Barbarian observes:
Actually, they don't much of the time. And if you have one eye, it becomes a permanent problem. It's a small defect, but a persistent one.
They do indeed most of the time, except when things are very close (and at a certain distace) to your face at strange angles.
So it's bad "design", but not too bad. Not likely. Even worse, for animals like rabbits, the blind spot is not corrected by overlap. it's less of a problem for animals with binocular vision, but still a problem.
Barbarian on the dishonest editing of Darwin's statement:
Actually, Darwin showed how it could have evolved in a series of steps. He asked a rhetorical question about the development of the eye just before he answered it. The less honest creationists take the quote and remove the part where he explains how, so as to make it appear that Darwin thought something he did not. Apparently they fooled you.
Yes I know what Darwin wrote all very well, and nobody fooled me.
Then it's a mystery to me why you quoted him in a way that made it appear he thought something he did not.
Anyway. Moving on, lets take a look at your Darwinian style model of how the eye could have evolved. As a point to note, you are using examples within different kinds, and not of the same kind.
"Kind" is a religious doctrine, not a scientific term. There is no biological entity as "kind". However, they are all members of the same phylum, in some cases, (as in the limpet/snail and nautilus/squid cases, they are very close. We can go to other members such as the abalone:
Notice that the fundamental layout remains the same for all mollusks, but the details of the way the basic structure works remains the same. We see this throughout living things, with a hierarchial structure of functionality, which can be explained only by common descent.
Here's the highly complex eye of the octopus:
Notice that while it has become analogous to the vertebrate eye in many ways, the fundamental structuring is identical to that of the very simple limpet, rather than to the superficially similar vertebrate eye. Why should two eyes so similar be basically so different? This is a complete mystery to "design" enthusiasts, but perfectly understandable in light of common descent. Moreover, the genetic, biochemical, anatomical, embryological, and fossil evidence confirms this finding.
For this reason, an evolutional path cannot be traced,
No, that's wrong. We can easily trace an evolutionary path, and in doing so, we find that a great deal of independent evidence gives us the same path.
However, since it is unfair to expect it of you to provide evidence of such variation within a single kind (partly because fossil records give no or little information about the workings of the eye (and even if they did, I doubt they would help you much),
Actually, in some cases, we can show the evolution of eyes by fossil records. The evolution of the three types of trilobite eyes from the generalized arthropod omnitidium.
The first, and most common type of eye in trilobites is the holochroal:
The omnatidia are very small and there is no sclera between lenses. Corneal membrane over surface only.
The second type, which is a modified holochroal eye, is the Schizochroal.
There are relatively few lenses, there is a deep sclera between the lenses, and the corneal membrane goes deep into the sclera. They resemble the developing eyes of holochroal trilobites, and developed by a process of paedogenesis, the retention of juvinile forms in adults. It is this type that evolved a doublet lens with spherical aberration controlled by an "aspheric element".
The third type, the abathochroal,
has small eyes, with few lenses, separated by a shallow sclera and with embedded corneal membranes.
partly because it could be argued that the fossil record doesn't go back far enough) I'll be kind and ignore this point, valid though it is.
Where eyes are preserved in the fossil record, they show common descent.
So your first example, the limpet. If you mean primative in the evolutionary sense, then I'd say no, fossil records agree with creationists, that limpets have always been... yes, you guessed it, limpets. I take it you mean primative in terms of complexity as a comparitive study?
Actually, both. You're mistaken about limpets. They have evolved from coiled shelled snails very early on:
Dollo's law and the re-evolution of shell coiling.
Collin R, Cipriani R.
Smithsonian Tropical Research Institute, Unit 0948, APO AA 43002, USA. rcollin@naos.si.edu
Gastropods have lost the quintessential snail feature, the coiled shell, numerous times in evolution. In many cases these animals have developed a limpet morphology with a cap-shaped shell and a large foot. Limpets thrive in marginal habitats such as hydrothermal vents, the high-energy rocky intertidal areas and fresh water, but they are considered to be evolutionary dead-ends, unable to re-evolve a coiled shell and therefore unable to give rise to the diversity seen among coiled snails. The re-evolution of a coiled shell, or any complex character, is considered unlikely or impossible (Dollo's law) because the loss of the character is followed by the loss of the genetic architecture and developmental mechanisms that underlie that character. Here, we quantify the level of coiling in calyptraeids, a family of mostly uncoiled limpets, and show that coiled shells have re-evolved at least once within this family. These results are the first demonstration, to our knowledge, of the re-evolution of coiling in a gastropod, and show that the developmental features underlying coiling have not been lost during 20-100 Myr of uncoiled evolutionary history. This is the first example of the re-evolution of a complex character via a change in developmental timing (heterochrony) rather than a change in location of gene expression (heterotopy).
There's a lot more about it (obviously, shelled marine animals fossilize a lot more often than many other organisms). Would you like to learn more about it?
Barbarian on the primitive molluscan eye:
Notice that it is not much but a few sensitive cells in a depression. It has a limited amount of acuity, in that it can tell from what direction the light is coming.
Barbarian continues:
Nautilus eye:
Notice that it's pretty much like the limpet "eye", except that the depression has deepened, and the tissue has grown over the depression to make a primitive "iris" and "pupil".
Wow! Wait one second! Not much different? It now has a retina,
The Limpet has a retina. It's just a simple one.
and the photoreceptor cells are very different
A little. But they are basically mollusk photoreceptors, just modified a bit.
it's even able to see polarized light.
All receptors can do this a little. You can do it a bit yourself.
If, when the Sun is setting, you take a look overhead you might see a faint, purplish, bow tie-shaped area oriented to the north. Haidinger's Brush is your reception of polarized light. Some organisms are a lot better at it than humans and lipets. But it's just an improvement of what we already have. That's a persistent theme in evolution.
Together with the other changes you have mentioned, these changes would require a huge amount of successive micro-evolutional changes which mean a growth in the gene pool;
It could take millions of years. But the evidence is that it does not. Simulations done by Dan-Erik Nilsson show that it could happen very quickly:
unless that is, that this information is already in the gene pool
If you believe in special creation, that won't work for animals, since each organism can have at most two alleles for every locus. Hence, variation must ultimately come about by mutation.
Barbarian observes:
Much more useful, and capable of forming a crude image by diffraction, much as a pinhole camera works. A lens is nice, but unnecessary.
I agree that in the case of the Nautilus that a lens is unnecessary, it has no requirement for better vision, but in the case of resolution requirement for most vertebrates to function as they do, a lens is required.
Yep. Although, a lens like that is better than nothing. A crude image of a mouse, produced by the infrared "eyes" of a rattlesnake serve perfectly well. As you see, the evolution of eyes in mollusks did not stop at pinholes.
Furthermore, I agree it is also true that this arangement is more useful for a nautilus over the optical arrangement the limpet has. So far all this shows to me is design that meets requirements.
Design fails to explain this in two ways. First, it doesn't explain why we see eyes becoming increasingly complex and effcient, as the evolutionary history of the phylum procedes. Second, it can't explain why the organisms like mollusks and vertebrates with complex eyes have them as modfied versions of the simpler ones in their own phylum. On the other hand, common descent makes that very clear.
As a note on the side though. I don't know who told you that a pinhole camera works by diffraction; but this is certainly not true. It works by limiting the range of incident parallel photons that reach the cameras image plate to the diameter of the pinhole. Though diffraction of photons can occur at the pinhole itself, this is not what forms the image, it only forms a diffraction pattern relating to the wavelength of the incident photons, the grating separation (or in this case apature size) and the distance of the imaging plate to the grating/hole. This pattern bears no ressemblance to the object the camera is imaging.
Hmm... that's right. My bad.
Barbarian continues:
Snail eye
Not much different, except the cuticle has grown over the opening to provide a transparent protection for the pinhole, preventing it from being damaged or clogged.
Again, a huge amount of difference when you look at the detailed differences between these eyes, requiring huge amounts of micro-evolutional change.
I don't see how. A cuticle growing over the pinhole requires a "huge amount of microevolutional change?" That makes no sense to me.
Have you studied any of these examples that you are giving in any depth at all???
Well enough to know how to dissect some of them. I know a good deal about the embryonic tissues from which eyes develop in the two phyla. Would you like to talk about that?
Barbarian continues:
Squid eye:
Not much different, except the cuticle and epithelium have thickened over the pinhole to form lenses.
Aside from shape, and a couple of other features this eye couldn't be much more different! I bet I could list more differences than you could list similarities!
It's very similar. Shape is the least of it. Notice that the basic design remains the same, only the cuticle had thickened a bit, and changed the way light is transmitted.
Ah, but the greatest leap is, how do you get from the cephalopod to the vertebrate eye?
You don't. They evolved separately.
Ah, but you may say, the vertebrate eye didn't evolve from the modern cephalod eye, but they descended from different ancestors. The point is, that these ancestors must have evolved from a common ancestor at some point. Therefore we come back to the same reasoning and options that we came back to the other day...
1. That the original kind (or ancestor) has a lot more genetic information than the descendants, carrying many dormant genes and chromosomes, allowing for the descendants to come without any additional genetic information.
Genetically, that's impossible, since we see entirely different genes responsible for the differences. Also we see that the eyes arise from entirely different tissues:
2. That the original kind (or ancestor) was less complex, and that the descendants gained genetic information over a period of time by “evolutional forcesâ€Â, becoming distinct kinds in their own right through natural selection and other means, even “fathering†new kinds their of their own.
It's bit more interesting than that.
Read about it here:
http://wwworm.biology.uh.edu/evodevo/ca ... haud02.pdf
This latter view has been excused by the evolutionists that have really thought about it and studied it. Why? Well it comes down to the only mechanism that can in anyway give new genetic information, mutation. In fact it doesn't even do that, it only makes variations (alles) of what is already there.
That is new information. For example, a few people have been lucky enough to be descended from a man who had a mutation that produced a substance conferring a strong resistance to atheriosclerosis. They have information for one more protein than homozygotes.
So why can't this be a mechanism for macro evolution?
It's been observed to produce macroevolutionary change.
The modern evolutionist is called a neo-Darwinian. He still accepts Darwin's ideas about natural selection, but something new (neo-) has been added. The modern evolutionist believes that new traits come about by chance, by random changes in genes called mutations, and not by use and disuse.
No, that's wrong. Traits usually spread or die out in a population by natural selection. Natural selection is not due to chance. Perhaps your guy means that new alleles appear in a population by chance. That's true. But whether they spread or die out is not by chance.
According to the modern, neo-Darwinian view, mutations are the source of new traits for evolution, and selection culls out the fittest combinations (or eliminates the "unfittest") that are first produced just by chance. Mutations certainly occur, but are there limits to extrapolating from mutational changes to evolutionary changes?
Yep. We need to always remember that individual don't evolve; populations evolve. Your guy doesn't seem to have that quite clear.
Do they produce evolutionary changes? Do they really produce new traits?
Yep. That's been directly observed. Would you like some examples?
Do they really help to explain that postulated change from molecules to man, or fish to philosopher?
Ah, he's thinking of the Cartoon Theory of Evolution, not the real one. In the real one, molecules never mutate and become men. Fish never mutate and become philosophers. Forget mutant turtles. It's not like that.
There are three major problems or limits (and many minor ones) that prevent scientific extrapolation from mutational change to evolutionary change.
(1) Mathematical challenges. Problem number one is the mathematical. I will not dwell on this one, because it's written up in many books and widely acknowledged by evolutionists themselves as a serious problem for their theory.
Hmm... I've never seen it. Since much of evolutionary theory is mathematical (indeed Hardy, of Hardy-Weinberg fame, was a mathematician) that seems to be wrong. Perhaps you could explain what he means.
Fortunately, mutations are very rare.
Depends on what you mean. Almost every human has a couple or so.
They occur on an average of perhaps once in every ten million duplications of a DNA molecule (10 to the 7th power, a one followed by seven zeroes). That's fairly rare. On the other hand, it's not that rare. Our bodies contain nearly 100 trillion cells (10 to the 14th power). So the odds are quite good that we have a couple of cells with a mutated form of almost any gene.
He's got that wrong. It's probable that there are millions of our cells with mutations. Do the math. Many cells reproduce hourly. What he should know is that most germ cells (eggs and sperm) have a mutation or two. So in all our genes, there are mutations which we can pass on.
The mathematical problem for evolution comes when you want a series of related mutations. The odds of getting two mutations that are related to one another is the product of the separate probabilities: one in 10 to the 7th power times 10 to the 7th power, or 10 to the 14th power.
That's like saying the odds of getting two heads in a row is 0.25. If you already have tossed one head, what's the odds of another heads? It's 0.5.
Does this suggest to you what's wrong with the argument?
That's a one followed by 14 zeroes, a hundred trillion! Any two mutations might produce no more than a fly with a wavy edge on a bent wing. That's a long way from producing a truly new structure, and certainly a long way from changing a fly into some new kind of organism. You need more mutations for that. So, what are the odds of getting three mutations in a row? That's one in a billion trillion (10 to the 21st power). Suddenly, the ocean isn't big enough to hold enough bacteria to make it likely for you to find a bacterium with three simultaneous or sequential related mutations.
Let's see.. take a deck of cards, and shuffle it well, and deal out the cards one by one, noting the order. The likelihood of that order is one, divided by about: 8,065,817,517,094,387,857,166,063,685,640,400,000,000,000,000,000,000,000,000,000000,000,000,000,000,000,000,000,000
Yet it happens every time. I'm not impressed. Astoundingly unlikely things happen all the time. Now, if someone unfamiliar with earth biology could look at a sponge, and predict a giraffe, I'd be impressed.
Let's take a look at you personally. The likelihood of you, given the alleles of your great, great-grandparents is even smaller.
So now, we've "proven" that it's impossible to produce you, or a shuffled deck of cards. Do you see what's wrong with the argument? The design people found an arrow in a tree, and painted a bulls-eye around it.
It was at this level (just four related mutations) that microbiologists gave up on the idea that mutations could explain why some bacteria are resistant to four different antibiotics at the same time. The odds against the mutation explanation were simply too great, so they began to look for another mechanism--and they found it. First of all, using cultures that are routinely kept for long periods of time, they found out that bacteria were resistant to antibiotics, even before commercial antibiotics were "invented."
Some of them existed before. But you've been somewhat misled. You see, those "natural antibiotics" evolved as means to deal with other microorganisms. Naturally, some of them evolved counter-measures. That surprised no one. what surprised people unfamiliar with evolutionary theory was that the genes rapidly spread through other bacteria.
Here's why; bacteria have a form of sexual reproduction called "conjugation" in which bits of genome are swapped. The key is that this happens between widely-different species as well as within species. So useful genes, no matter where they evolve, rapidly spread through all exposed populations.
On the other hand, we sometimes know precisely when the mutation occured, and which gene mutated. Barry Hall's work with E. coli, showed how irreducible complexity, in the form of an entirely new regulator, evolved by random mutation and natural selection. Another such gene, one for metabolizing nylon (not surprisingly, that one was not found to be widespread) we know exactly when and how it appeared.
Bacteria can be made antibiotic resistant by mutation, but biologist Novick {9} [1445] calls such forms "evolutionary cripples". The mutation typically damages a growth factor, so that the mutationally crippled bacteria can scarcely survive outside the lab.
No, that's wrong. The evolved form of nylon-eating bacteria, for example, took over from other forms in the waste pools in which they evolved.
Contrary to popular opinion, drug resistance in bacteria does not demonstrate evolution.
No, that's wrong, too. In fact, we are holding off bacterial resistance by designing antibiotic usage protocols based on evolutionary principles. It's working. Further, Barry Hall is actually plumbing the mechanisms of evolving resistance to predict how to counter it when it appears.
"A scientist at the University of Rochester has created genetic conditions in the laboratory that mimic natural evolution. Biology professor Barry Hall said his research has implications in the race against fast-mutating, antibiotic-resisting bacteria.
Hall and his team demonstrated that their lab model of evolution and genetic mutation is so accurate that it can be used to predict how a strain of bacteria will become resistant to existing pharmaceuticals. The advance will give researchers a possible tool to create new drugs to which the bacteria cannot adapt. "
http://sci.newsfactor.com/perl/story/16869.html
Way back in 1967, a prestigious group of internationally known biologists and mathematicians gathered at the Wistar Institute to consider Mathematical Challenges to the Neo-Darwinian Interpretation of Evolution. {10} [1445] All present were evolutionists, and they agreed, as the preface clearly states, that no one would be questioning evolution itself. The only question was, could mutations serve as the basis--with natural selection--as a mechanism for evolutionary change? The answer of the mathematicians: No. Just plain no!
In fact, the "evolutionists" were not quite "a prestiegious group of internationally known biologists and mathematicians." One was actually an electrical engineer, who may have never taken a college course in biology! Dr. Murray Eden actually contended:
"It is
our contention that if “random†[chance] is given a serious and crucial interpretation from a probabilistic point of view, the randomness postulate is highly implausible and that an adequate scientific theory of evolution must await the discovery and elucidation of new natural laws, physical, chemical and biological.â€Â
I have given an 8th grade class of average students a simulation that shows how chance and natural selection determines the sorting of alleles in a population. They rather easily grasped the concept. I hope the gentleman was misquoted, because this quote indicates a terrible misunderstanding of evolutionary processes even for an electrical engineer.
Upward or downward? Even more serious is the fact that mutations are "going the wrong way" as far as evolution is concerned. Almost every mutation we know is identified by the disease or abnormality that it causes.
No, that's wrong, too. Most don't do anything noticeable. A few are harmful, and a very few are favorable. The ratio depends on the environrment and the organism. Well-adapted organisms in an unchanging environment will have few favorable mutations, as almost any change is likely to be netural or unfavorable. A recent immigrant population in a new environment is mathematically more likely to have favorable mutations, and that is what we see in the real world.
Creationists use mutations to explain the origin of parasites and disease, the origin of hereditary defects, and the loss of traits. In other words, time, chance, and random changes do just what we normally expect: tear things down and make matters worse.
True. Without natural selection, this is exactly what would happen.
Using mutations to explain the breakdown of existing genetic order (creation-corruption) is quite the opposite of using mutations to explain the build up of genetic order (evolution).
True. This is why so few scientists remain creationists. We can see how natural selection takes random change and makes organisms more fit, not less fit.
As a matter of fact, human beings are now subject to over 3500 mutational disorders. Fortunately, we do not show as many defects as we carry.
Right. I use a simulation to show students why evolutionary theory predicts that harmful recessive alleles tend to remain in the population at a very low level.
Mutations are mostly harmful,
Nope. Most don't do anything at all.
and, as time goes on, they impose an increasingly heavy "genetic burden" on a species. The turkey above, lacking a second set of genes to mask its hereditary defects, could scarcely survive. Creationists use mutations to help explain the origin of parasites and disease. Some evolutionists still believe that time, chance, and occasional favorable mutations provide the raw material for "upward-onward" progress, but the "post-neo-Darwinists" are looking for other means to explain evolution.)
Apparently, they're having trouble convincing the regular Darwinists, who have no trouble accounting for the evidence with random mutation and natural selection.
Now here's the basis for a good horror story. Picture a mirror at the end of a dark hall. You claw your way through the spider webs to reach the mirror, and then you press a button. The mirror then splits you in two halves, so you can see what you would look like if you had only your mother's genes or only your father's genes. In the next scene, you're writhing there in agony, your hair turning white as you fall over backward and die of fright! Unfortunately, that picture exaggerates only slightly what mutations have done to human beings and to the various kinds of plants and animals as well. If it weren't for having two sets of genes, few of us would be able to survive.
If there weren't oxygen in the atmosphere, you'd fall over dead, too. We'd be quite a bit different, if we were haploid. But evolution can explain why diploid organisms can carry many harmful recessives, with rarely a problem.
Evolutionists recognize, of course, the problem of trying to explain "onward and upward" evolution on the basis of mutations that are harmful at least 1000 times more often than they are helpful.
Nope. It's part of evolutionary theory. You've been misled on that one. Natural selection.
No evolutionist believes that standing in front of X-ray machines would eventually improve human beings.
That's like saying that your car needs oil to run, so if you add more oil, it will run better. The opposite is true.
No evolutionist argues that destruction of the earth's ozone layer is good because it increases mutation rates and, therefore, speeds up evolution.
There's a good reason for that. You do know that we don't necessarily think further evolution of humans is a good thing, don't you?
Evolutionists know that decrease in the ozone layer will increase mutation rates, but they, like everyone else, recognize that this will lead only to increased skin cancer and to other harmful changes. Perhaps a helpful change might occur, but it would be drowned in the sea of harmful changes.
Hmm... no. Evidence shows that often, as in in sunny climates, melanism is selected for, and populations there evolve darker skins.
Because harmful mutations so greatly outnumber any supposed helpful ones, it's considered unwise nowadays (and illegal in many states) to marry someone too closely related to you. Why? Because you greatly increase the odds that bad genes will show up.
Remember, that's not a problem unless you get the same two defective alleles. Which is rare unless you marry a sister or cousin. Not surprisingly, animals generally tend to avoid mating with siblings.
After a short study, I'm sure you'll realise why evolutionists are unable to give an explanation as to how such an instrument could have evolved - it is too perfect.
I've spent a lot of time on it. And the answer turns out that nothing is perfect, and we can show how the "sorta perfect" evolved.
I don't doubt that you have spent time looking at these things, but you haven't gone deep enough. Maybe I shouldn't have said "short study". You should try spending a bit more time looking a little deeper at all the differences and thinking about how these differences can be reconciled in a common ancestor.
I've spent many years studying it. The more I look, the more evidence there is.
Furthermore, is there any evidence that this common ancestor ever existed?
Yes, quite a bit.
The eye itself is complex, but it is not an irreducable machanism. Even so, it still reveals these fatal problems to the serious evolutionists.
If so, I never met a serious evolutionist. And I've met a lot of gentlemen and women who knew a great deal about it.
My guess is you don't have a lot of formal training in biology.
It is obviously far harder to show than you realise according to lead evolutionists that cannot give a mechanism that gives rise to the required micro-evolutional changes for marco-evolutional scale - mutation certainly can't explain this!
What "lead evolutionist" would that be? We can directly observe this happening.
I like your snake example, although it doesn't help you at all, its only using genes that are already there in the gene pool of snakes. This is not macro evolution, it's just diversity in kinds.
I would like to know which genes you are speaking of. I wasn't aware that you knew which genes are responsible. Tell me about them.
Barbarian observes:
The point is that it isn't the same snake. It's an entirely different organism, one that can hunt in darkness, and "see" heat.
No, it's not an entirely different organism, it's still a snake, that is only genetically using information it already has.
Barbarian replies:
Chimps and humans differ by much less than garter snakes and rattlesnakes.
It now seems you are making things up here, since this is obviously wrong!
No, it is quite true. Genetically, behaviorally, anatomically, humans and chimps are far closer than rattlesnakes are to garter snakes.
This is the dilemma of creationism. If the evolution of boid snakes is not evolution, then the common ancestry of humans and chimps isn't either.
Where is the dilemma? Evolution of boid snakes, is not evolution (in the sense of the theory of evolution) at all, it is just the use of genes that are already pre-existant.
I'm skeptical. Show me.
As I say, it's not that much different at all to other snakes, it is only a snake using the diversity of genes they already have. Thus it is harldy evidence for macro-evolution.
If the evolution of an entirely new sensory organ is not evolution, then what are we to say of humans and chimps, for which neither has any anatomical feature the other does not?
: Anyway, there's a perfectly good convex lens in mollusks, without the necessesity of a defect like a blind spot.