Refuting Comfort's Eye evolution claims

As I mentioned in my last post, Comfort and Cameron will be distributing co-opted copies of Darwin's ...Origin... I've looked at the introduction Comfort wrote. Of course it contains the same old tired anti-evolutionist arguments that have not changed in hundreds of years, despite the fact the field of evolutionary biology has matured into a rich, detailed, predictive science that forms the core of modern understanding of all biology.

[If you don't read the entire rather long post, please read the last 2 paragraphs]

A prime reason evolutionists don't often debate these simplistic claims is that it's been done before, for hundreds of years, and anti-evolutionists keep re-using the same tired arguments, ignoring advances in science. Scientists really like to argue, but not about things that have been resolved for hundreds of years, over and over again, in increasing detail.

Comfort's simplistic, tired arguments are no exception. I'll focus on his section on eye evolution. The arguments boil down to:

1. It looks soooo complex. It had to be designed.
2. Comfort can't imagine how "random" processes could drive evolution.
3. There are a bunch of parts working together, and each couldn't originate without the other.

Of course there is nothing new here. For #1, Hume famously critiqued the design argument in the 1700's. It part, this is a false analogy: Watch is to human designer as Complex biological feature is to God.

#2 Natural selection is not a random process, e.g. Blind Watchmaker.
#3 There is no evidence that "separate" parts of the visual system cannot work separately, and in fact it is known that parts DO function separately. As one of many possible examples, the cnidarian polyp Hydra magnipappillata uses photosensitivity without eyes or brain (ref).

Below, I will paste Comfort's text, and a few comments on his text.

Or, consider the human eye. Man has never developed a
camera lens anywhere near the inconceivable intricacy of the
human eye. The human eye is an amazing interrelated system of
about forty individual subsystems, including the retina, pupil,
iris, cornea, lens, and optic nerve. It has more to it than just
the 137 million light-sensitive special cells that send messages
to the unbelievably complex brain. About 130 million of these
cells look like tiny rods, and they handle the black and white
vision. The other seven million are cone shaped and allow us
to see in color. The retina cells receive light impressions, which
are then translated into electric pulses and sent directly to the
brain through the optic nerve.

A special section of the brain called the visual cortex
interprets the pulses as color, contrast, depth, etc., which then
allows us to see “pictures” of our world. Incredibly, the eye,
optic nerve, and visual cortex are totally separate and distinct
subsystems. Yet together they capture, deliver, and interpret
up to 1.5 million pulse messages per millisecond! Think
about that for a moment. It would take dozens of computers
programmed perfectly and operating together flawlessly to
even get close to performing this task.

Yes, eyes are pretty complicated - that is one reason they are fun to study and understand from a scientific perspective.

The eye is an example of what is referred to as “irreducible
complexity.”

There is no evidence that eyes or any other biological structure are 'irreducibly complex'. Here is a paper describing processes that have led to the evolutionary origins of "phototransduction", the cascade of protein signaling events that results in animals' ability to detect light.

It would be absolutely impossible for random
processes,

It would indeed be difficult for purely random processes to evolve complex systems, but natural selection is not a random process.

...operating through gradual mechanisms of genetic
mutation and natural selection, to be able to create forty
separate subsystems when they provide no advantage to the
whole until the very last state of development.

This is factually wrong. For example, one of these eye "subsystems" provides an advantage to Hydra even though the animal does not possess other of the "subsystems". As mentioned above, Hydra utilizes phototransduction without lens, retina, brain, or even pigment cells. One response to light is for the animal to scrunch into a ball, hypothesized to purge its one-way gut at first morning light. [If there is a designer, at least She had a sense of humor when She made one-way guts - what a great design that is!]. So as evidenced by mouse trap tie clips in the Dover trial; claims of irreducible complexity usually represent a lack of imagination about what sub-systems can do.

Ask yourself
how the lens, the retina, the optic nerve, and all the other parts
in vertebrates that play a role in seeing not only appeared
from nothing, but evolved into interrelated and working parts.

This sounds like an argument against divine design, which claims that eye parts came from dust. In fact evolutionary biology teaches us that proteins of the lens came from other proteins.

Evolutionist Robert Jastrow acknowledges that highly trained
scientists could not have improved upon “blind chance”:

To paraphrase Orgel - evolution is cleverer than you are; that doesn't mean that goddidit. Again, natural selection is not "blind chance".

The eye appears to have been designed; no designer
of telescopes could have done better. How could
this marvelous instrument have evolved by chance,
through a succession of random events? Many people
in Darwin’s day agreed with theologian William
Pauley, who commented, “There cannot be a design
without a designer.”

William Paley, not Pauley. Yes it is truely amazing that evolution produced eyes, and other complex things like livers or brains. Nevertheless, it is a well established scientific fact that evolution did produce these traits.

And this marvelous design occurs not just in humans, but
in all the different creatures: horses, ants, dogs, whales, lions,
flies, ducks, fish, etc. Think about what the theory of evolution
claims: the eyes, in working pairs, of all these creatures slowly
developed over millions of years. Each of them was blind until
all the parts miraculously came together and interrelated with
the others, because all parts are needed for the eye to function.
Then each creature had its two eyes work in harmony with
the brain to interpret those images. Fortunately, each of these
creatures simultaneously evolved whatever matching parts
each would need: sockets, skin, eyelids, eyelashes, tear ducts,
muscles to blink, etc.

Again, Comfort is arguing more against his own claims that against evolution. Eyes appearing separately in every tetrapod is VERY unlikely, but this is what the creationist fable of eye origins would entail. In fact, evolutionary biology teaches us that all living things share a common ancestry, and that shared features usually evolved once, prior to the common ancestor of creatures sharing a trait. This is backed up by mounds of genetic evidence showing shared use of many genes in most animal eyes, including opsin, Pax-6, and many more.

You’ve probably been led to believe that the first simple
creatures had rudimentary eyes, and that as creatures slowly
evolved their eyes evolved along with them. However, that’s
not what scientists have found. Not only is there no evidence


Robert Jastrow, “Evolution: Selection for perfection,” Science
Digest, December 1981, p. 86.

It is simply false that scientists have found the first simple creatures to have had complex eyes. "The first simple creatures" Comfort seems to be referring to are trilobites. There are highly complex arthropods, far far far removed from the first simple creatures. Trilobites are not even the first animals, not even the first arthropods.

of this occurring, but some of the most complex eyes have
been discovered in the “simplest” creatures.
Riccardo Levi-Setti, professor emeritus of Physics at the
University of Chicago, writes of the trilobite’s eye:

"This optical doublet is a device so typically
associated with human invention that its discovery in
trilobites comes as something of a shock. The realization
that trilobites developed and used such devices half a
billion years ago makes the shock even greater. And a
final discovery—that the refracting interface between
the two lens elements in a trilobite’s eye was designed
in accordance with optical constructions worked out
by Descartes and Huygens in the mid-seventeenth
century—borders on sheer science fiction...The design
of the trilobite’s eye lens could well qualify for a patent
disclosure. "

--Riccardo Levi-Setti, Trilobites (Chicago: University of Chicago
Press, 1993), pp. 57–58.

How could the amazing, seeing eye have come about
purely by blind chance? Based on the evidence, wouldn’t a
reasonable person conclude that the eye is astonishingly
complex and could not have evolved gradually, and that each
creature’s eyes are uniquely designed?

Even Charles Darwin admitted the incredible complexity
of the eye in The Origin of Species:

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 formed by natural selection,
seems, I freely confess, absurd in the highest degree."

Even more incredible, though, is that Darwin went on
to say that he believed the eye could nonetheless have been
formed by natural selection. He was right on one point. If a
Designer is left out of the equation, such a thought is absurd
in the highest degree.

Yes, it is still amazing - and still true - that eyes evolved. No natural selection still cannot be equated with blind chance.

At least he included the end of this famous quote, where Darwin writes that anyone with any bit of logical reasoning ability can see that evolution can produce even complicated things.


I didn't spend a lot of time on this because these arguments of Comfort are not worth a lot of my time. They are tired, recycled, un-creative jabs at evolution that have been known to be false for hundreds of years.

In the end, I'll use Comfort's own words to describe what he is doing to evolution. He was writing about Buddhism, but his words apply nicely to his ignorance of evolutionary biology:

Amazingly, the religion of Buddhism [substitute 'Ray Comfort' for 'Buddhism'] denies that God [substitute 'Evolution' for 'God'] even exists. It teaches that life and death are sort of an illusion. That’s like standing at the door of the plane and saying, “I’m not really here, and there’s no such thing as the law of gravity, and no ground that I’m going to hit.” That may temporarily help you deal with your fears, but it doesn’t square with reality.

A few word changes lead to:

Amazingly, the religion of Cameron and Comfort denies that evolution even exists. It teaches that two hundred years of hard work by countless scientists across the globe to elucidate the details of evolution are sort of an illusion. That’s like standing at the door of the plane and saying, “I’m not really here, and there’s no such thing as the law of gravity, and no ground that I’m going to hit.” That may temporarily help Comfort and Cameron deal with their fears, but it doesn’t square with reality.

Evolutionary origin of a light sensitive nerve

The origin of a light sensitive nerve was almost certainly an early step in the evolution of animal eyes, and this was thought to have happened only once, some 600 million years ago. But new open access research on the nematode C. elegans indicates a heretofore unknown instance where a nerve evolved light sensitivity.

One of the common, but incorrect, claims of anti-evolutionists is that the origin of complex features like eyes cannot be explained by evolutionary biology. As an example (although perhaps not written by an anti-evolutionist) see the comment on this post. For some history and a response to the incorrect anti-evolutionists claim, see this post.

It turns out that, as is often the case, the difficulty in understanding comes from trying to make a continuum into a dichotomy. An eye or even the genetic machinery for light sensitivity doesn't have to be all there or all not there. Instead, these features can build up gradually, by classical Darwinian evolution.

An early step in the evolution of complex eyes was almost certainly the origin of a light sensitive nerve. Darwin imagined that nerves might easily become light sensitive, but because of a lack of understanding of the molecular basis of photoreception, not to mention the molecular mechanisms of heredity, he could not even fathom a guess as to how nerves came to see the light. But just because Darwin didn't know how the machinery of light sensitivity could be built gradually by evolution doesn't mean it couldn't occur gradually.

Light sensitivity is a multi-step genetic process, where one protein signals to another. But all those proteins were not "turned on" all at once to suddenly allow for light sensitivity. Instead, light sensitivity evolved from existing "senses". Many signals are detected outside of a cell and they trigger proteins to send a signal inside a cell. Even yeast use proteins to sense pheromones outside their single cell and direct growth toward a potential mating partner. Many of these signaling genes are shared across all of our senses, and we can pinpoint by comparative study when a signaling gene became a light sensitive protein called opsin (again see this).

This brings us to the worm research. C. elegans has no visible eyes and its genome lacks light sensitive opsin genes. Yet it does display sensitivity to UV light!

Here is a link to a video showing light sensitivity.

How does it do this without opsin? It turns out that a different protein has become light sensitive. In this case, homologous proteins are known to be taste receptors (Gustatory receptors) in insects. Therefore, at some point in evolutionary history, the worm protein
gained light sensitivity, independently of the opsin "light switch"!

This is really fantastic work that suggests many new lines of research. For example, the mechanism of photoreception is unknown for the worm gustatory/light receptor. If this could be understood, we could get a specific idea about how a protein gained light sensitivity during evolution. Second, it is not known when light sensitivity was gained, which would require comparative study. These genes are present in insects - are the insect genes light sensitive? It would be great fun to put an insect gene in a worm to see if it could rescue the loss of light sensitivity due to a mutation.

Finally, I'll point out that this work is similar to another study published just last month . That workfocused not on the receptor, but on genes later in the cascade; especially on the gene responsible for "firing" (ie changing the concentration of the ions in) the light sensitive nerve. It turns out that that the "firing" gene is homologous to the "firing" gene used in vertebrate rod and cone cells - another example of how evolution often uses similar tools to produce parallel results.

Evolutionary Origins of Phototransduction

Below is a section of an article I am drafting on eye evolution. Does it make sense? Any parts impossible to understand? Comments are welcomed!



In The Origin of Species, Darwin hypothesized that the first step in the evolution of eyes involved the gain of photosensitivity in a nerve, writing, “…I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light…” Here, Darwin was making the assumption that variation leading to light sensitivity of previously non-light-sensitive nerves was abundant, and that natural selection could then act on that variation. But how did those specific variations originate? How does a nerve become light sensitive? In his notebook, Darwin suggested that it might be impossible to understand how a nerve gained light sensitivity. He wrote “to show how the first eye is formed, — how one nerve becomes sensitive to light, ...is impossible.” Since the mechanisms of heredity and the molecular mechanisms of photoreception were unknown in Darwin’s time, no specific hypothesis could even be posed about the genesis of light perception. One hundred and fifty years later, things have changed.


Today, through an understanding of the distinct evolutionary histories of the components of vision, and more specifically of phototransduction (the signaling pathway that turns light into a nerve signal), we can now pose a specific historical hypothesis for their origin: Phototransduction originated within animals by modifying an existing signaling pathway. More specifically, at some time before the divergence of jellyfish and humans, but likely after the split common ancestor of sponges and humans, the first light sensitive animal opsin protein originated. This protein did not originate from nothing, nor was it newly breathed into an ancient animal genome by a designer. Instead, opsins arose by mutation of an existing receptor to render it light sensitive. This historical hypothesis makes numerous predictions, and available data are consistent with the hypothesis. It also makes predictions that have not yet been tested, indicating promising areas for future research.






If the hypothesis that phototransduction arose within animals is valid, then some components of phototransduction should exist within animals, but should not exist (or should possess a different function) outside of animals. Such is the case for opsin, which is present as the primary photopigment gene in most animals. Recent research shows that various cnidarians, including a hydra, a sea anemone, a hydrozoan, and a box jellyfish, possess opsins (Plachetzki et al, 2007; Suga et al, 2008; Kozmik et al, 2008). At the same time, opsins are absent from sponges and non-animals (See Figure). In science, demonstrating the absence of something like a gene is difficult, because a skeptic can always invent a reason why the target was accidentally missed. In the case the opsins in question, scientists have determined the entire genome sequence of the sponge Amphimedon queenslandica, the choanoflagellate Monosiga and numerous fungi, making the presence of opsin in those organisms very unlikely. Some proteins of near-animals are in fact rather similar to opsins, but in every case the non-animal receptors lack characteristics that specifically define opsins. Therefore, although opsins might have been present at the origin of animals and lost in sponges, their absence instead strongly suggests that they originated within animals, before the split common ancestor of humans, insects, and cnidarians, all of which possess opsins.


With current knowledge that opsin is the basis of light sensitivity, Darwin’s question of how a nerve becomes light sensitive can be rephrased as, “how did animal opsins originate”? Proteins rarely originate from nowhere, and opsins are no exception. Opsins form a subfamily within a larger family of proteins called G-protein coupled receptors (GPCRs), also sometimes called serpentine proteins because they snake back and forth across cell membranes. Since serpentine proteins are present in all animals and their close relatives - including sponges, Monsiga, and fungi - this broad class of proteins long predates animals. In yeast (a fungus), these receptors are sensitive to pheromones and they even direct a signal through proteins homologous to non-opsin phototransduction proteins. As such, a signaling pathway exists outside animals, which is very similar to phototransduction, except the receptor protein detects pheromones, not light. Receptors outside animals share some characteristics with opsin, like snaking through a cell membrane seven times. It is one of these serpentine proteins that served as the progenitor of the first opsin protein, as evidenced by the similarity of opsins and other serpentine proteins.


Darwin’s question can be refined farther, to “how did a serpentine protein gain the ability to respond to light?” And since opsin’s light sensitivity is mediated by its ability to bind a light reactive chemical, called a chromophore, the question can be even further refined to ask how a GPCR must be modified to bind a chromophore. In the case of opsin, we know that a particular amino acid – a Lysine in the 7th membrane-spanning region – binds to the light reactive chemical. Presumably then, a mutation changing an amino acid in the 7th trans-membrane region of a light insensitive GPCR was involved in the acquisition of light sensitivity in animals. This fateful mutation coupled with numerous other mutations, are responsible for the origins of eyes and vision. Although science has not yet tracked down every single mutation involved in the evolution of vision, the origin of opsins clearly illustrate, in richer detail than Darwin might have imagined, the natural processes that gradually allow the evolution of complex features.