“Simple” Vision Is Too Much for Evolution
The complexities of human visual consciousness
exceed the capabilities of evolutionary processes
by J.Y. Jones, MD*
*Creation-Evolution Headlines welcomes Dr. J.Y. Jones, retired ophthalmologist and eye surgeon, for this inaugural post.
Let me say at the outset that two basic fully formed kinds of eyes occur in nature, the complex eyes of most non-vertebrates; and the simple eye of humans and other vertebrates, plus a few echinoderms. Of course, there are numerous other creatures that have some kind of eyes, such as clams, snails, and myriad other creatures, but a discussion of these is beyond the scope of this article. Hopefully I can address other types in a later article.
Here are two scientific papers that might be of use in understanding the first few steps of vision, my only criticism being that they do insufficient justice to the true complexities involved. While there may be allusions to evolution in these scientific papers, it is by no means the central theme. Having read thousands of articles in ophthalmology publications over the years, I can testify that evolution is a subject seldom mentioned in ophthalmic literature, especially when the articles are constructed by ophthalmologists such as myself.
From Eye to Brain
I. Kronemer et al., Human visual consciousness involves large scale cortical and subcortical networks independent of task report and eye movement activity. Nature Communications 13, 7342 (2022). DOI: 10.1038/s41467-022-35117-4
This paper more than anything else punctuates how many incredible complexities are involved in vision. Though we have some insight into how the eye works, when it reaches the occipital cortex we mostly lose sight of where and how it comes to consciousness. We, after 50 years in the field for me, still have no idea of even the pathways that lead occipitally processed vision to come to consciousness—we know practically nothing about it.
Through MRI and EEG studies done with various visual stimuli, this article sheds a bit of new light on the subject, finding in 144 volunteer subjects some potential pathways to consciousness. As always when studying most living systems, the “how” is much harder to detect and delineate than the “where”. To follow is the abstract of the paper by Kronemer and 27 co-authors:
The full neural circuits of conscious perception remain unknown. Using a visual perception task, we directly recorded a subcortical thalamic awareness potential (TAP). We also developed a unique paradigm to classify perceived versus not perceived stimuli using eye measurements to remove confounding signals related to reporting on conscious experiences. Using fMRI, we discovered three major brain networks driving conscious visual perception independent of report: first, increases in signal detection regions in visual, fusiform cortex, and frontal eye fields; and in arousal/salience networks involving midbrain, thalamus, nucleus accumbens, anterior cingulate, and anterior insula; second, increases in frontoparietal attention and executive control networks and in the cerebellum; finally, decreases in the default mode network. These results were largely maintained after excluding eye movement-based fMRI changes. Our findings provide evidence that the neurophysiology of consciousness is complex even without overt report, involving multiple cortical and subcortical networks overlapping in space and time.
This is a very good article with an innovative approach to figuring out the mysteries of vision. Still, ultimate answers are elusive and may never be found, despite monumental efforts in that direction. There seems to be something about life, something inanimate and nonmaterial, that simply defies explanation and frustrates attempts to get to the bottom of basic questions.
On a Personal Note
I believe the visual system, like most body systems, is far more complicated than envisioned, even among highly educated observers. I’ve always wondered about exactly what happened when Jesus healed the man born blind in the Bible in John 9 (as opposed to the man who presumably became blind in Mark 8:22-26). Jesus obviously knew that it was imperative that He reconstruct practically the entire nervous system of the man born blind, since the man would not have been able to walk or otherwise function without a fully developed nervous system, of which about a third of neural fibers have something to do with vision. He had learned to negotiate in his blindness through touch and sound, to be sure, but normal people navigate visually. This requires through visual stimulation the full development of the ocular visual apparatus, the optic nerve, the lateral geniculate bodies, the occipital lobe, the known pathways of vision (optic tracts and radiation), the unknown pathways that connect vision to conscious experience.
Vision More than Meets the Eye
Additionally, the highly important proprioceptors in the body’s skeletal muscle (and elsewhere) are a vast part of the system. These proprioceptors (meaning “own receptors”) clue normal people as to where they are and quietly help them to complete the current step and anticipate the next step, and vision is perhaps the major force in adjusting one’s body appropriately. With all these in full atrophy, a regressive process had occurred all over the body of the man (or anyone) born without vision. Absent early visual stimuli, it’s no small feat to put all these back in order in a grown man who’s never experienced vision. Left to “just vision” he’d likely have been more helpless than ever, at least for a time, and he likely would never have experienced the full benefits of normal vision. We can surmise that he had no such issues, since he obviously appeared normal to those who had known him as a blind man, to his parents who testified that he was born without vision, and to the Sanhedrin (the Jewish governing body) when they accused him and punished him as being a fake of some kind.
A personal story: I did 18 mission trips doing surgery in Honduras, 7 in Jamaica, and scattered ones in other places. I was riding high on success during our ~1990 mission in Siguatepeque, Honduras, numerous people coming to the clinic with total blindness (except light) due to cataract. I had been feeling unduly good about my surgery, but God brought my high opinion of myself, my misplaced pride, down rather dramatically and quickly. A tattered couple from the back country was there with their only child, a baby girl in arms, whom they had dressed up well beyond their means to see the big Gringo doctor doing “miracles” at the hospital. I sauntered into the exam room, fresh from another successful cataract operation, and told them optimistically in Spanish, “Dejeme mirar a su hija.”
What I found immediately floored me: That child had only pea-sized eyes, totally opaque and obviously nonfunctional! I was stunned far more than I could ever express, and my head spun as I reached for the nearest chair, calling my wife Linda to come in from the next room. I stammered through tear-filled eyes, “Hon, please pray for them. I can’t!” I sat there in silent tears as she prayed, knowing as she did that my help was far inferior to what they needed. I still remember the humiliation, the helplessness, and the lesson I was given that every person I could help was a GIFT from God, and that He had plenty to present me that were light years beyond my limited abilities. It’s a lesson that followed me wherever I went in subsequent years, and I never forget it, especially if and when my inappropriate self-confidence flared.
II. Palczevski, Chemistry and Biology of Vision. J Biol Chem. 2012 Jan 13; 287(3): 1612–1619 (cited without internal references).
This attenuated outline of how the eye generates an electrical impulse in each photoreceptor has changed practically not at all since my days in training some fifty years ago. The Abstract reads:
Our visual system operates over an extremely broad dynamic range, detecting variations in light intensity of over 8 orders of magnitude, from single photons to more than one-hundred million photons. This dynamic range is attributed to adaptation processes in rods and cones, with the remainder arising from pupil contractions, processes within inter-retinal neurons, and the production rate of visual chromophore. The rod cell saturates at several thousand photons, whereas cones continue to function at several millionfold higher light intensities. The central foundation of our vision is the photochemical isomerization of the vitamin A-derived visual chromophore (11-cis-retinal) from its cis- to trans-configuration. A single photon of light isomerizes a single 11-cis-retinal bound to rod or cone opsins. A photon carries ∼2.5 eV energy (at 500 nm), but only a fraction (1.5 eV/opsin molecule) is utilized to elicit changes in retinal conformation and subsequently protein conformational changes, whereas the remaining energy is dissipated. The high excess of energy ensures that photoisomerization occurs with high fidelity. To renew a functional receptor after photoactivation, the chromophore must be regenerated metabolically through a series of enzymatic processes that include isomerization and oxidation of all-trans-retinyl ester to 11-cis-retinal. Enzymatic re-isomerization of all-trans-retinoid to 11-cis-retinoid requires only 3–4 kcal/mol energy (or 0.13–0.17 eV/molecule).
How the Eye Prevents Brown-Out
What is not stated is the rapidity with which the 11-cis-retinal is regenerated for the next visual task, so fast that a mere blink is many times slower than this enzymatic preparation of the photoreceptor for more action. Simply sweep your eyes over any scene, and realize that the visual system is extremely busy so you don’t “brown out” even while looking at some magnificent scene such as the Grand Canyon.
What Is Required for Binocular Vision
Beyond this fantastic feat, more “magic” comes into play as all impulses are gathered by the retinal nerve fiber layer (a transparent membrane that light must actually pass through to reach the photoreceptors*).
*This arrangement of the nerve fiber layer so that light must pass through it to reach the photoreceptors has been criticized by evolutionists (e.g., by Nathan Lents) as a design flaw, to the effect that any proposed omnipotent Creator would have designed the eye so that this passage wouldn’t be necessary. Subsequent attempts to discredit this design for some other arrangement have been shown, for various reasons, to fall short in major ways, and that this is the only workable and logical arrangement for sharpest vision and best nourishment of the nerve fibers, among other benefits. See Jonathan Wells’ explanation at Evolution News.
These axons pass out of the eye via the optic nerve, where they partially cross where the two nerves meet at the optic chiasm, the nasal fibers from one eye plus the temporal fibers from the other eye leaving the chiasm as the optic tract heading for the lateral geniculate body. This is an important basis for the miracle of binocular vision, since the nasal and temporal fibers from each eye see basically the same image at the same time, and without this near-impossible crossover there would be nothing but confusion in the lateral geniculate body, with only scrambled images for one eye vying for acceptance as a visual image. Curiously, this is not a problem if a person loses one eye, because the occipital cortex is able to put the nasal and temporal images together from one eye into one image.
Note: Try closing one eye just to be sure you don’t have homonymous hemianopsia!** This hemianopsia is most often caused by a stroke or tumor involving visual areas after passing the chiasm. Bitemporal hemianopsia is a rare condition, usually cause by upward pressure on the optic chiasm by a pituitary or some other kind of tumor.
**Homonymous hemianopsia is a condition in which a person sees only one side ― right or left ― of the visual world of each eye. The person may not be aware that the vision loss is happening in both eyes, not just one.
Defects of Binocular Vision
Before going into the function of the lateral geniculate body and beyond, let me note that quite a large number of people do not have binocular vision, sometimes due to amblyopia (failure of an otherwise normal eye to develop normal vision—very much a treatable problem in young people, and a major reason why visual screening should be done before beginning school), injury or disease in one eye, various ocular mobility problems such as Duane’s syndrome, etc. People who grow and develop without binocular vision do not get double vision after a stroke or other trauma damages one or more of the three nerves to the extraocular muscles of each eye. The muscles of both compound eyes (arthropods mainly) and simple eyes (virtually all vertebrates) will hopefully be discussed in a future article.
Summary: From Cornea to Consciousness
From the chiasm, the divided optic nerves, or optic tracts, continue without synapse to the lateral geniculate bodies on either side of the temporal lobe of the brain. There the first synapse occurs, and the optic radiation (formed by axons of geniculate body neurons) carries the impulse (actually millions of them) to the occipital cortex on the posterior aspect of the brain. There the vision is processed, and by unknown pathways it is passed immediately to consciousness, thought to reside in the the frontal lobe of the brain.
Comment: It is most futile to try to reconstruct any logical development of such a system by random, “blind” processes. Evidence of design shouts from every aspect of the incredible visual system. The very notion that such a system evolved spontaneously surely is absurdity at its zenith.
J.Y. Jones MD has been an eye physician and surgeon for five decades. He is a decorated Vietnam veteran, speaks Spanish, and has volunteered in 28 overseas eye-surgery mission trips. He has received numerous awards for writing and photography, and is a frequent speaker at sportsmen’s events, where he particularly enjoys sharing his Christian testimony. J. Y. and his wife Linda have been married since 1964.
Dr. Jones is an avid hunter who has taken all North American big game species using the same Remington .30-06 rifle, resulting in the book One Man, One Rifle, One Land (Safari Press, 2001); Dr. Jones helped Safari Press produce the Ask the Guides series, their most successful North American hunting books. He has written 14 books and some 300 short articles for various periodicals.
Excellent article, thank you for sharing your knowledge with us.