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Eyes and Evolution: Why Do Some With Eyes See Not?
In the great satirical movie Duck Soup (first released 79 years ago to the date of this post), Mrs. Gloria Teasdale (Margaret Dumont), the financial underwriter of the nation of Freedonia, recruits Rufus T. Firefly (Groucho Marx) to be the insolvent country’s new president. The opposition then retains two spies, Chicolini (Chico Marx) and Pinky (Harpo Marx), to work for them. Toward the end of the film, in a bedroom scene with Teasdale, the spies both dress like Firefly in order to secure the combination to a safe. After she gives the combination to one Firefly (the disguised Pinky), Mrs. Teasdale watches him leave the room, but suddenly another Firefly (the disguised Chicolini) appears. Teasdale confronts Chicolini who denies leaving and blusters “Well, who you gonna believe, me or your own eyes?” He knew that Teasdale had convincing evidence against him. She was, after all, an eye-witness. And yet, she did not understand.
Perhaps more than on any other of our senses, humans rely on sight. Our camera eyes allow massive amounts of information to enter our brain, first through the lens at the exterior of the eye, and then from the inverted image on the retina at the back of the eye by way of the optic nerve. In the plains of Africa, our ancestors stood to gather information about their surroundings. Today we focus on ironically named smartphones, not so much to hear audio transmissions, but to stare at screens with text or other visual data.
So important is sight to us that over two-thirds of the sensory cells in our bodies are the light sensing cells in our eyes. So energy consuming is the human retina that it uses more oxygen per gram than does the brain. (Shubin, Your Inner Fish (Pantheon Books 2008), at 150; Lane, Life Ascending (W. W. Norton 2009) at 175.)
Our eyes are not only the mechanism by or through which we focus on our surroundings, they are also at the focal point of a broader picture and a serious controversy. One hundred and thirty years after the death of Charles Darwin, some who do not accept the validity of biological evolution pioneered by him, argue that the complexity of the eye disproves evolutionary theory. In Jewish circles today, the argument is advanced in several quarters, including Rabbi Joseph Ginsburg and Prof. Herman Branover writing for chabad.org, media executive Jonathan Rosenblum, scientist and author Dr. Gerald Schroeder, and the Hanesfesh Community, an organization of Jewish students, among others.
The arguments tend to overlap. United by a fundamentalist belief in a supernatural Author of Creation and centered on a fundamental disbelief that a complex organ such as the human eye could have evolved by small, adaptive mutations over time, Jewish opponents of evolution argue that the statistical probabilities of life emerging spontaneously are somewhere between non-existent or abysmally low, that macroevolution has not been proven, that there is no fossil or other record that demonstrates how a human eye could have developed, and that an intelligent designer in the form of a supernatural God is a much better explanation for the existence of the human eye.
For the general proposition that the statistical probability of life forming from an inorganic soup is extraordinary small, Ginsburg/Branover, Rosenblum and Hanefesh refer to British cosmologist Fred Hoyle. It’s an argument from authority, without the authority. Hoyle was an astronomer not a bio-chemist. He rejected the notion that life could have emerged on Earth because he believed it more probable that life on this planet was seeded by extraterrestrial sources. (See Lane, above, at 9, 12.) Do the Hoyle acolytes really want to go down that road? Neither offers any comment on Hoyle’s extraterrestrial origin theory, let alone its validity.
In his book The Science of God (Free Press 2009) (“TSOG”) and his website, Schroeder also attempts a statistical critique, but without reference to Hoyle and for a somewhat different purpose. Schroeder argues against macroevolution by claiming that the 30-34 body plans we see today appeared suddenly during the Cambrian period about 530 million years ago and that the statistical odds of these forms evolving by chance from 10390 possible combinations of amino acids is impossible. We have criticized Schroeder before (see posts of Oct. 18, Oct. 31 and Nov. 9, 2011), and this excursion outside of his area of purported expertise in the physical sciences does not redeem him.
Schroeder is correct that there was an explosion of life forms during the Cambrian period. The reason is not clear, as physical scientists and life scientists suggest different reasons. (See Ruse & Travis, Eds., Evolution: The First Four Billion Years (Belknap Press of Harvard U. Press 2009), at 784-86.) This does not mean, though, as Schroeder contends, that there was no biological evolution in the Precambrian period. There was, and Schroder notwithstanding, there is even fossil evidence of multicellular soft-bodied animals during that time. (Id.)
Nor can Schroeder’s statistics save his argument. Indeed, the low-probability game can be played in reverse. For instance, Victor Stenger, a physicist, astronomer and philosopher, not only deflates probability like arguments in his book The Fallacy of Fine-Tuning (Prometheus Books 2011), he also purports to demonstrate statistically that the existence of God is unlikely. (See Id. at 245-55.) At least Stenger recognizes that the outcome of these exercises depends on the assumptions made and is therefore highly unreliable. (See Id. at 252.)
In the last twenty years, there have been serious scientific studies conducted which suggest possible mechanisms for the creation of life from pre-biotic conditions on Earth. A review of the science, involving the geology of deep sea hydrothermal vents and the impact of protons on molecules through a process called chemiosmosis, is described by biochemist Nick Lane in his book Life Ascending (above at 8-33). No one can be sure, of course, about the conditions on earth some four billion years ago. There may, consequently, be more than one explanation for how raw materials developed into the DNA/protein world in which we find ourselves. This is not a deficiency of science, merely an example of how science probes for the truth. In the end, though, “the existence of different abiotic mechanisms by which biochemical monomers can be synthesized under plausible prebiotic conditions is well established.” (See Ruse & Travis, above, at 73.) The mystery about the specifics remains, and the specifics are obviously important, but there is no reason to believe that the problem is unsolvable. (Id. at 72, 74.)
Evolution deniers do not stop at questioning the origin of life, they attack the concept generally and specifically. Ginsburg/Branover claim that macroevolution, the descent of life from a common ancestor through a process of mutation and selection, is neither fact nor a scientific theory. Rosenblum complains that “Darwinists” have not observed the “mechanism” by which a common ancestor to, say, whales and humans have been “fashioned,” nor “can Darwinists explain how complex systems, such as human sight, none of whose component parts would alone provide any advantage, could have come into being by a long series of micro-mutations.” Similarly, talking of the human eye specifically, Hanefesh suggests that the eye is a poor candidate for “coordinated evolution.” It notes some of the problems that can interfere with decent vision, e.g., a fuzzy cornea, an opaque lens, a failure of the pupil to dilate, and states that “(t)he eye either functions as a whole, or not at all.” For his part, after another excursion heavy on math but silent on specific biological steps required for the development of a complex eye, Schroeder argues not only about the statistical improbability of the evolution of the human eye, but also that the independent evolution of convergent forms is “so highly improbable as to be functionally impossible.” (See TSOG, at 110-18.)
We do not know what, if any scientific literature, any of the evolution deniers have read, but it does not seem to be much, and certainly not current or critically accepted. A good starting place for those seriously interested in exploring the development of species is Your Inner Fish (above) by University of Chicago paleontologist Neil ShubIn. Wonderfully written, Professor Shubin looks at fossils in rocks and genes in cells which mutually trace and reinforce a story of development and speciation from ancient fish to modern vertebrates, including primates, including us. Where Shubin looks at shapes and functions, biochemist Nick Lane tends to discuss processes in his somewhat denser book, Life Ascending (above).
This is not to say that evolution as initially conceived by Charles Darwin is not subject to review and refinement. Given the passage of time since the publication of Darwin’s seminal work, that his nineteenth century understanding of biological evolution has been found imperfect should not be surprising. Discoveries in bio-chemistry and paleontology would inevitably call for modification of his views. (See, e.g., Kirschner and Gerhart, The Plausibility of Life (Yale U. Press 2005).) But for all of these amendments, and the debate about gradualism and punctuation, Darwin’s concept of evolution remains one of the great scientific formulations of all time, and one that has been accepted as the consensus view of the development of life on earth: (1) species descend from a common origin with modification effectuated by a process of change in traits or characteristics, rather than being created in fixed form at the beginning of time, and (2) those better adapted to succeed in a particular environment will, resulting in the survival of the more fit based on genetic variation.
Both Shubin and Lane address vision and the history of the eye. As a paleontologist, Shubin is troubled by the absence of a substantial fossil record for eyes, but notes that “the really important work in the light-gathering cells happens inside the molecule that actually collects light.” (Shubin, above, at 152.) Moreover, despite the incredible variety of eyes, all animals use “the same kind of light-capturing molecule,” one which involves a protein known as an opsin. (Id.) Looking at opsins, tissues and genes, Shubin sees the bridge back in time to our primitive ancestors. (Id. at 148-57.)
Lane’s discussion of sight drills down further. (See Lane, above, at 172-204.) He acknowledges the challenge to natural selection by the existence of the complex human eye and proceeds to deal with it. He demolishes the notion of eye absolutism by showing that nature balances the competing interests of resolution and sensitivity in different ways over time. He shows how, in some circumstances, half an eye is better than no eye at all. He shows how the lens could have been assembled in the first instance, using available proteins. His conclusion: “there are no particularly difficult steps in the sequence to make an eye.” (Id. at 199.) Like Shubin, Lane also traces genetic information back to a common ancestor.
Lane also describes a 1994 study led by Dan-Eric Nilsson and Susanne Pelger of Lund University in Sweden which considered the specific adaptive steps necessary to evolve from a flatworm eyespot to a complex eye of a vertebrate. University of Chicago professor Jerry Coyne refers to the same study in his book Why Evolution is True (Penguin 2009). Given the approximate number of generations that would be required to reach the goal, the investigators determined that the entire process of evolution could be accomplished in about 400-500,000 years. In other words, there was ample time for independent evolution of eyes in dozens of groups of animals. (See Lane, above, at 182-86; Coyne, above, at 142-43.) Maybe Schroeder was not aware of the Nilsson-Pegler study when TSOG was first published in 1997, but surely he would have learned of it before his modified 2009 version was released. Yet there is no mention of the study in his book or on his website.
For those who want even more, ophthalmologist Dr. Ivan Schwab has written what appears to be the definitive work on the evolution of the eye. (See Evolution’s Witness: How Eyes Evolved (Oxford U. Press 2011).) Over the course of more than 250 pages, Schwab discusses and illustrates in detail the development of the incredible variety of eyes we know today from initial photoreceptors that existed over 3,700,000,000 years ago through various geologic periods and eras as manifested across various animal classes. Bird eyes, snake eyes, mollusk eyes, octopus eyes and human eyes, they and more are all here.
And the discoveries continue. Within the last month, scientists led by Dr. Davide Pisani of the University of Bristol have presented evidence to the National Academy of Scientists that LOCA, the last opsin common ancestor, was a placozoa that lived over 700 million years ago, earlier than previously believed. Within eleven million years, the three light sensing opsins we have today were developed.
All this data, all these studies, all of the articles, chapters and books place a heavy burden on the deniers and rejectionists. Their objections have been met and persuasively countered. No longer should the argument be about macroevolution or speciation. Rather, the onus is clearly on those who continue to deny evolution generally and that of the eye specifically to tell us why Shubin is wrong, why Lane is wrong, why Nilsson and Pegler are wrong, why Schwab and Pisani are wrong, why the history, chemistry, molecular biology, anatomy, genetics, physiology, geology and paleontology to which the scientists refer, and which importantly is mutually reinforcing, is wrong. While questioning and testing are appropriate, rote recitation of unsupported rhetoric is no substitute for reason, and the deniers need to elevate their argument or give it up.
The criticism from the Jewish sources identified here fails in large part because it is outdated, shallow and made casually, without serious regard for definition of terms or reference to serious studies. The question is why? The answer may be found in history.
The Jewish reaction to Darwin originally was quite mixed. Some reformers like Kaufman Kohler, who favored progressivism and transformation, embraced evolution while others did not. Similarly, some traditionalists opposed evolution while others found its gradualism appealing, as well as its seeming confirmation of the durability and adaptability of the Jewish People. What appeared to be at stake at that time was not so much science as the nature of contemporary Judaism itself. (See Ruse & Travis, above, at 360-61.)
Today one is hard pressed to find opponents of evolution across the spectrum from Reform, through the Reconstructionist and Conservative movements, to and including Modern Orthodoxy. While individuals might attribute a greater, lesser or no role to God in the evolutionary process, Jews as a group overwhelmingly tend to accept the reality of the process. Some, however, do not., and they are often, if not exclusively, ultra-Orthodox. (See Cantor & Swetlitz, eds., Jewish Tradition and the Challenge of Darwinism (U. of Chicago Press 2006) at 71-88.) The question, again, is why, why on this issue are these Jews different from all other Jews?
The answer cannot be that the rejectionists are necessarily smarter (or dumber) than the others, nor are they necessarily more devout or more internally consistent in their religious orientation than the others. There is no evidence to support any of those conclusions. Rabbi Natan Slifkin has suggested recently (Nov. 8, 2012) that there is a social aspect to this phenomenon, that one’s personal identity is at stake. The notion is that if They believe in evolution, We must not. Maybe. The idea of drawing lines, of separating, of distinguishing is hardly unknown in Jewish history and tradition.
But more seems at work here. Is it a communal insularity that has generated a suspiciousness even of natural forces? Is it an ethos of conformity that now extends beyond religious belief and behavior and has become a committed unwillingness to engage, to question? Is it an inability to see shades of gray? Is it a fear of some slippery scientific slope? Whatever the cause, the denial of reality, in the form of evolution or otherwise, does not seem destined to be a successful model for a healthy long term future.
A few things are for sure:
(1) There are not many Jews on this planet — only about 14 million — and 7,000 million non-Jews. We Jews don’t have minds to waste.
(2) Burying one’s head in the sand in order to avoid seeing reality is a myth about ostrich behavior, and would be counterproductive for human beings as well.
(3) Yirmiyahu (Jeremiah) was right (Jer. 5:21): Those who have eyes and see not, those who have ears and hear not are foolish indeed, and without understanding.
(4) Claiming that biological evolution does not operate in the world and failing to encourage the serious studying of science is like placing a stumbling block before the blind. (See Lev. 19:14.) It creates a dangerous obstacle to one’s wellbeing. It inhibits the full development of one’s understanding of and one’s ability to interact with the universe as it is and, further, with whatever Creative Force that may exist and permeate it.
So what now? Now, as the great sage Hillel once said (Shabbat 31a): “Zil gmar (go and study).”