Vestigial Organs

 

An abridged version of my article on vestigial organs appeared in the Chanukah issue (number 29) of Kolmus, a supplement to Mishpacha Magazine. Below is the full article, with notes.

*** 

A newspaper here in Johannesburg recently published an article on the alleged imperfections of the human body. The author of the article would not have had to search far to find material for her article. The Internet buzzes with sites that carry lists of God’s Great Mistakes[1], and Discover Magazine delights in articles that disparage miscellaneous parts of the human body.[2]

 The article is downright silly at times. In describing the human ear, it points out that its exquisite sensitivity is a liability because a sudden explosion could destroy the tiny crystalline rods in the ear whose function is to amplify the vibrations impinging on the eardrum. What next – proof that the human skeleton is shoddily constructed because of its inability to remain intact following a plunge from the tenth storey?[3] But the ear – amazing as it truly is – is not my subject.[4] In this essay, we will focus on the mascot of the vestigial organ movement, the human appendix, with which the article begins:

The human body is a wonder of nature: our brains react faster than a computer, our hearts beat without the need for rest. But it’s not perfect. The appendix, for instance, seems to have no real function yet can be the cause of appendicitis and, if left untreated, life-threatening peritonitis (inflammation of the abdominal lining) – so it could be simpler to get rid of it.

 Seems to have no real function, huh? In order to make that statement, one must be sure that the appendix really does not have a function, and making a negative argument like that is often dodgy.[5] In 1981, the Canadian biologist Steven Scadding argued that although he had no objection to Darwinism, “vestigial organs provide no evidence for evolutionary theory.” The primary reason is that “it is difficult, if not impossible, to unambiguously identify organs totally lacking in function.” Scadding cited the human appendix as an organ previously thought to be vestigial but now known to have a function.[6] What function does it have?

In October 1999, a Scientific American reader submitted the following question to the Ask the Experts column: “What is the function of the human appendix? Did it once have a purpose that has since been lost?”[7] The journal appointed Loren G. Martin, professor of physiology at Oklahoma State University, to answer the query. Professor Martin began by pointing out the contribution made by the appendix before a human being is even born:

For years, the appendix was credited with very little physiological function. We now know, however, that the appendix serves an important role in the fetus and in young adults. Endocrine cells appear in the appendix of the human fetus at around the 11th week of development. These endocrine cells of the fetal appendix have been shown to produce various… compounds that assist with various biological control (homeostatic) mechanisms. There had been little prior evidence of this or any other role of the appendix in animal research, because the appendix does not exist in domestic mammals.[8]

 Professor Martin then notes that in adulthood, the appendix continues to be an important player:

Among adult humans, the appendix is now thought to be involved primarily in immune functions. Lymphoid tissue begins to accumulate in the appendix shortly after birth and reaches a peak between the second and third decades of life… During the early years of development, however, the appendix has been shown to function as a lymphoid organ, assisting with the maturation of B lymphocytes (one variety of white blood cell) and in the production of the class of antibodies known as immunoglobulin A (IgA) antibodies. Researchers have also shown that the appendix is involved in the production of molecules that help to direct the movement of lymphocytes to various other locations in the body.[9]

 Professor Martin also notes that “the appendix probably helps to suppress potentially destructive humoral (blood- and lymph-borne) antibody responses while promoting local immunity… This local immune system plays a vital role in the physiological immune response and in the control of food, drug, microbial or viral antigens.”

 Finally, Professor Martin validates the adage that if something ain’t broken, you shouldn’t try to fix it:

In the past, the appendix was often routinely removed and discarded during other abdominal surgeries to prevent any possibility of a later attack of appendicitis; the appendix is now spared in case it is needed later for reconstructive surgery if the urinary bladder is removed. In such surgery, a section of the intestine is formed into a replacement bladder, and the appendix is used to re-create a ‘sphincter muscle’ so that the patient remains continent (able to retain urine). In addition, the appendix has been successfully fashioned into a makeshift replacement for a diseased ureter, allowing urine to flow from the kidneys to the bladder. As a result, the appendix, once regarded as a nonfunctional tissue, is now regarded as an important ‘back-up’ that can be used in a variety of reconstructive surgical techniques. It is no longer routinely removed and discarded if it is healthy.[10]

So we know that the appendix very definitely does have function. Enter William Parker.[11] Parker is a professor of surgery at Duke University School of Medicine who was sceptical of claims that the appendix is vestigial. His hypothesis was that it serves as a nature reserve of sorts for beneficial bacteria in our guts. When struck by severe gut infections such as cholera – an all-too-common scourge in human history – the beneficial bacteria in our guts are depleted. The appendix serves as a sanctuary for beneficial bacteria, which can ride out a bout of diarrhoea that completely evacuates the intestines, and emerge afterwards to repopulate the gut.[12]

In October 2007, Science Daily reported on this research.[13] “While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed,” said Parker, who conducted the analysis in collaboration with R. Randal Bollinger, Duke professor emeritus in general surgery.

 The gut is populated with different microbes – and there are more of them than there are human cells in a typical human body – that help the digestive system break down the food we eat. In return, the gut provides nourishment and safety to the bacteria. Parker believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria.

Science Daily reported that for the previous ten years, Parker had been studying the interplay of these bacteria in the bowels, and in the process had documented the existence in the bowel of what is known as a biofilm. This thin and delicate layer is an amalgamation of microbes, mucous and immune system molecules living together atop the lining of the intestines. “Our studies have indicated that the immune system protects and nourishes the colonies of microbes living in the biofilm,” Parker explained. “By protecting these good microbes, the harmful microbes have no place to locate. We have also shown that biofilms are most pronounced in the appendix and their prevalence decreases moving away from it.”

“Diseases causing severe diarrhea are endemic in countries without modern health and sanitation practices, which often results in the entire contents of the bowels, including the biofilms, being flushed from the body,” Parker said. He added that the appendix’s location and position – the appendix is a dead-end sac that hangs between the small and large intestines – is such that it is expected to be relatively difficult for anything to enter it as the contents of the bowels are emptied.

“Once the bowel contents have left the body, the good bacteria hidden away in the appendix can emerge and repopulate the lining of the intestine before more harmful bacteria can take up residence,” Parker continued. “In industrialized societies with modern medical care and sanitation practices, the maintenance of a reserve of beneficial bacteria may not be necessary. This is consistent with the observation that removing the appendix in modern societies has no discernible negative effects.”[14]

Parker’s idea implies that individuals with their appendix should be more likely to recover from severe gut infections than individuals without an appendix. His hypothesis was tested a few years after he floated it. In its December 2011 issue, the journal Clinical Gastroenterology and Hepatology published a study entitled “The Appendix May Protect Against Clostridium difficile Recurrence”.[15]

Ideally, in order to test Parker’s idea, scientists would compare the fates of individuals who suffer gut infections and have an appendix to those of individuals who suffer the same gut infections and do not have an appendix. But such a study would be easiest in developing countries where cholera and similar diseases are prevalent, and those same regions are the ones where medical records (of appendectomies, for example) tend to be least detailed.

James Grendell, chief of the division of Gastroenterology, Hepatology and Nutrition at Winthrop University Hospital in New York, solved the problem, together with his colleagues. They studied a pathogen called Clostridium difficile. Thisdeadly organism is often encountered in hospitals, particularly when patients must be treated by prolonged courses of antibiotics. It does not appear to compete well with the native biota of patients’ guts, but when the native biota is depleted (as is the case after several courses of antibiotics) Clostridium difficile can grow quickly and take over. It is most dangerous when, after treatment, it recurs, which is to say when the native fauna of the gut and immune system cannot, together, prevent it from reinvading. If Parker was right, individuals without an appendix should be more likely to have a recurrence of Clostridium difficile than those individuals with an appendix.

The researchers were able to find 254 patients at the hospital who met the requirements of their study: there was evidence of their having been infected by Clostridium difficile, and the presence or absence of an appendix was known or discernible. The rest was easy. They compared whether individuals without their appendix were at a higher risk of recurrence from Clostridium difficile. The results were dramatic. Individuals without an appendix were four times more likely to have a recurrence of Clostridium difficile, exactly as Parker’s hypothesis predicted. Recurrence in individuals with their appendix intact occurred in 11% of cases. Recurrence in individuals without their appendix occurred in 48% of cases.

The results do not unequivocally prove Parker’s thesis, but they do provide further strong circumstantial evidence for the hypothesis that the human appendix plays an important role in human health. 

***

So, through ingenious science, a number of important functions have been found for the appendix, and human knowledge has advanced. Still, if that’s all there was to it, the topic would remain esoteric, limited to specialists in academic medicine. But that’s not all there is to it.

The uselessness of the appendix is a long-standing urban legend, going back at least as far as Charles Darwin. Darwin argued in The Origin of Species that the widespread occurrence of vestigial organs – organs that may have once had a function but are now useless, mere vestiges of the past – is evidence against Creation. “On the view of each organism with all its separate parts having been specially created, how utterly inexplicable is it that organs bearing the plain stamp of inutility… should so frequently occur.” But such organs, he argued, are not only explained by his theory, but would even have been predicted by it: “On the view of descent with modification, we may conclude that the existence of organs in a rudimentary, imperfect, and useless condition, or quite aborted, far from presenting a strange difficulty, as they assuredly do on the old doctrine of creation, might even have been anticipated in accordance with the views here explained.”[16]

This argument was then bequeathed to subsequent generations of biologists. It was endorsed as recently as 2001 by Ernst Mayr, one of the leading biologists of the twentieth century: “Every shift into a new adaptive zone leaves a residue of no longer needed morphological features that then become an impediment. One only needs to think of the many weaknesses in humans that are remnants of our quadrupedal and more vegetarian past, for instance… the caecal appendix.”[17]

When making his overall argument, Darwin used some examples of apparently vestigial organs which, I think, are uncontroversial. Some cave-dwelling fish are completely blind, although they possess eyes; others have no eyes at all. The species Astyanax mexicanus is born with eyes, but, as it matures, skin grows over the eyes and they degenerate completely – there is no need for sight in the dark world of a troglodyte. The eyes of blind cavefish are vestigial, and this appears to have happened through disuse. Darwin wrote that “It appears probable that disuse has been the main agent in rendering organs rudimentary. It would at first lead by slow steps to the more and more complete reduction of a part, until at last it became rudimentary, as in the case of the eyes of animals inhabiting dark caverns…”[18]

But as evidence for biological evolution, sightless cave-dwelling fish are weak. Firstly, as everyone who has built towers with blocks in the company of a two-year-old knows, there is a big difference between constructing and demolishing. A toddler is quite capable of bashing down impressive edifices, but cannot pile more than two or three blocks on one another. The fact that disuse can lead to the atrophying of an organ is by no means indicative of a purposeless, natural process being capable of constructing an organ where none previously existed. Whatever process leads to the loss of an organ’s abilities must be demonstrated to be capable of creative activity, if vestigial organs are to serve as evidence for biological evolution. As the biologist Lynn Margulis put it, “Natural selection eliminates and maybe maintains, but it doesn’t create.”[19]

Secondly, in the case of eyes, there is no doubt as to their function – to provide sight – which is superfluous in pitch-black caves. Even if cave-dwelling fish had perfectly-functioning eyes, they would still be useless, because there is no light in the caves these fish inhabit. It is therefore reasonable to posit that the eyes of blind cavefish functioned in the distant past, but atrophied over time due to lack of use. But when it comes to other apparently-vestigial organs, whose function in the distant past we do not know with certainty, the conclusion does not inexorably follow that they are really vestigial.

The parathyroid gland is a good example of this last point. It was discovered in humans in 1880. All through the early twentieth century biologists surmised that these glands were among the many useless parts they believed existed in the human body. Not anymore. The parathyroid is now known to regulate calcium-phosphorous metabolism,[20] and also plays a role in magnesium metabolism by increasing its excretion.[21] [A similar narrative is associated with tonsils: the removal of tonsils may lead to a higher incidence of throat cancer, but for decades doctors never suspected that this “useless” tissue might actually have a use that escaped their detection.[22]] In the decades when it was claimed that the parathyroid glands are vestigial, the argument rested on ignorance. Not only did nobody know what the parathyroid does now, nobody knew what the parathyroid was ever supposed to have done. To have claimed that these glands are vestigial was to argue from ignorance. We now know better.

Back to the appendix. In The Descent of Man, Darwin cited the human appendix as an example of a vestigial organ.[23] As we saw earlier, Darwin was wrong. In his time, immunology and endocrinology can barely have been said to exist. How wise was it, in retrospect, to label the appendix vestigial? And if we now confront an organ that appears to have no function, how wise is it to label it vestigial? And once we agree that labelling organs as vestigial is premature unless we know with certainty what their function was in the distant past, what happens to these organs’ role as evidence for biological evolution?

A final point. Not only does the appendix not provide evidence for biological evolution, it in fact constitutes a difficulty for the evolutionary paradigm. The appendix is found in both marsupial creatures, like the wombat, and in placental mammals, such as rats, lemmings and humans. But since, according to evolutionary theory, the last putative common ancestor of marsupials and placental mammals did not possess an appendix, evolutionists are forced to believe that the same organ evolved twice, independently.[24] Needless to say, this is fantastically improbable.[25]

Darwin of the Gaps

One of the curious twists in the story we have followed is the role reversal. In the past, proponents of scientism often threw the God of the Gaps argument in the face of believers. The argument is supposed to work like this. Believers, wallowing in ignorance, would explain sundry aspects of nature with a shrug and “God did it” or “That’s how God wanted it to be”. But as science progressed, and one dark corner after another was illuminated by the light of reason and empirical evidence, the believers had to retreat. The gaps in our understanding of the natural universe shrank, leaving less and less for God to accomplish.

The God of the Gaps argument was always silly, but in the case of vestigial organs the shoe – of a decidedly uncomfortable fit – is on the other foot. Biologists made the claim about various organs that they must be the product of evolution. But this argument depended on the claim that these organs had no function and thus had to be vestiges of a more-useful past. But as human knowledge expands, we find that structures that were previously assumed to be without function in fact have important function. With each of these steps, evolutionary biologists have had to retreat.

***

 And what about the Jewish angle? Well, the Talmud teaches that everything that God created has a purpose.[26] And Maharal (ca. 1520-1609), one of the greatest Jewish philosophers of the past half-millennium, wrote that even if we do not understand every feature of the human body, yet we are quite certain that nothing in it is superfluous.[27] Are those viewpoints compatible with the notion that our bodies are littered with useless vestiges of the past? I am not sure that these statements are sufficient to preclude the conclusion that wisdom teeth, for example, are vestiges of a past in which our diet was substantially different to what it is nowadays. But I do know this. The left atrial appendage is a small muscular ‘pouch’ in the heart. Dr. Amanda Varnava, a cardiologist quoted in the newspaper article I cited at the beginning of this essay, says that “It is completely redundant – it has no functional role.” It would be prudent to reserve judgment.[28]


[1] See http://oolon.awardspace.com/SMOGGM.htm.

Retrieved 8th April 2013.

[2] See http://discovermagazine.com/2004/jun/useless-body-parts#.UWKY5qJT6Ag.

Retrieved 8th April 2013.

[3] The Star, Wednesday, 20th March 2013, page 36, The Bits of Your Body that Nature Got Wrong, by Lucy Elkins:

The human body is a wonder of nature: our brains react faster than a computer, our hearts beat without the need for rest. But it’s not perfect. The appendix, for instance, seems to have no real function yet can be the cause of appendicitis and, if left untreated, life-threatening peritonitis (inflammation of the abdominal lining) – so it could be simpler to get rid of it.

EARS… Once the ear drum has collected the noise vibrations, they are passed into the inner ear. Here, the noise vibrations are picked up by tiny crystalline rods that look like hairs. “These are very fine and help make our hearing especially sensitive by adding volume and clarity,” [ENT specialist Tony Wright] adds. But this sensitivity also means the rods are prone to damage. “Something like an explosion can destroy them instantly – and persistent loud noise of 85 decibels or more (such as in a noisy factory or a disco) can damage them over years. The problem is that we can’t regenerate them.”

The article can be read online:

http://www.iol.co.za/lifestyle/body-parts-we-just-don-t-need-1.1476443#.Ub7GQeel4dU

Retrieved 17th June 2013.

[4] To read about some of the latest research regarding the astonishing abilities of the human ear, see http://www.evolutionnews.org/2013/03/our_ears_are_am070551.html.

Retrieved 14th June 2013.

[5] מסכת מנחות דף קג עמוד ב במשנה: אין לא ראינו ראיה.

[6] Steven R. Scadding, “Do ‘vestigial organs’ provide evidence for evolution?” Evolutionary Theory 5 (1981): 173-176. See this article by Dr. Jonathan Wells:

http://www.evolutionnews.org/2009/05/the_myth_of_vestigial_organs_a020111.html

Retrieved 14th June 2013.

[7] See http://www.scientificamerican.com/article.cfm?id=what-is-the-function-of-t

Retrieved 10th April 2013.

[8] A report on LiveScience dated 29th May 2006 states:

The appendix is a slimy, dead-end sac that hangs between the small and large intestines.  It’s about a half inch in diameter and three inches long.  As quickly as 11 weeks after conception, the appendix starts making endocrine cells for the developing fetus.  Endocrine cells secrete useful chemicals, such as hormones, and the appendix endocrine cells secrete amines and peptide hormones that help with biological checks and balances as the fetus grows.

See http://www.livescience.com/10489-appendix-slimy-worthless.html.

Retrieved 14th April 2013.

[9] The same LiveScience report also makes the following point:

http://www.livescience.com/10489-appendix-slimy-worthless.html

After birth, the appendix mainly helps the body stave off disease by serving as a lymphoid organ.  Lymphoid organs, with their lymphoid tissue, make white blood cells and antibodies.

The appendix, by virtue of its lymphoid tissue, is part of a complicated chain that makes B lymphocytes (one variety of white blood cell) and a class of antibodies known as immunoglobulin A antibodies.  The appendix also produces certain chemicals that help direct the white blood cells to the parts of the body where they are needed the most. 

[10] There is a sinister side to this surgical versatility. In 2001, rumours were circulating in Greek hospitals that surgery residents, eager to rack up scalpel time, were falsely diagnosing hapless Albanian immigrants with appendicitis. At the University of Ioannina medical school’s teaching hospital, a newly minted doctor named Athina Tatsioni was discussing the rumours with colleagues when a professor who had overheard asked her if she’d like to try to prove whether they were true – he seemed to be almost daring her. She accepted the challenge and, with the professor’s help, eventually produced a formal study showing that, for whatever reason, the appendices removed from patients with Albanian names in six Greek hospitals were more than three times as likely to be perfectly healthy as those removed from patients with Greek names. “It was hard to find a journal willing to publish it, but we did,” recalls Tatsioni. “I also discovered that I really liked research.” See http://www.theatlantic.com/magazine/print/2010/11/lies-damned-lies-and-medical-science/308269/.

Retrieved 6th May 2013.

[11] My account of Dr. Parker’s work is based on an article on the website of Scientific American. It can be read here: http://blogs.scientificamerican.com/guest-blog/2012/01/02/your-appendix-could-save-your-life/

Retrieved 9th April 2013.

[12] See Randal Bollinger R, Barbas AS, Bush EL, Lin SS, Parker W. Biofilms in the large bowel suggest an apparent function of the human vermiform appendix. Journal of Theoretical Biology, 2007 Dec 21; 249(4):826-31.

[13] See http://www.sciencedaily.com/releases/2007/10/071008102334.htm.

Retrieved 14th June 2013.

[14] About one person in twenty has the appendix removed.

[15] See the abstract here: http://www.cghjournal.org/article/S1542-3565(11)00580-5/abstract

Retrieved 9th April 2013.

[16] Darwin, The Origin of Species, Chapters XIV (p. 402) and XV (p. 420). Available online at http://darwin-online.org.uk/content/frameset?viewtype=side&itemID=F391&pageseq=430

Retrieved 14th June 2013.

[17] Ernst Mayr, What Evolution Is, Basic Books, page 143.

[18] Charles Darwin, Origin of Species (1859), sixth edition, page 401. See http://darwin-online.org.uk/content/frameset?keywords=caverns%20dark%20inhabiting%20animals&pageseq=430&itemID=F401&viewtype=text.

Retrieved 8th April 2013.

“By the time that an animal had reached, after numberless generations, the deepest recesses, disuse will on this view have more or less perfectly obliterated its eyes, and natural selection will often have affected other changes, such as an increase in the length of antennae or palpi, as a compensation for blindness.” Charles Darwin, Origin of Species (1859), sixth edition, page 111. See

http://darwin-online.org.uk/content/frameset?keywords=recesses%20the%20deepest&pageseq=139&itemID=F391&viewtype=text

Retrieved 14th June 2013.

[19] See http://discover.coverleaf.com/discovermagazine/201104?pg=68#pg70.

Retrieved 14th June 2013.

[20] See http://www.livescience.com/10489-appendix-slimy-worthless.html.

Retrieved 11th April 2013.

[21] parathyroid gland. (2009). Encyclopædia Britannica. Encyclopædia Britannica 2009 Ultimate Reference Suite.  Chicago: Encyclopædia Britannica.

[22] “Tonsillectomies have been linked to dozens of medical complications and conditions, ranging from polio to weight gain. A typical example is a study published in 2011 in the European Heart Journal. The study “found a higher risk of AMI [acute myocardial infarction] related to surgical removal of the tonsils and appendix before age 20. These results are consistent with the hypothesis that subtle alterations in immune function following these operations may alter the subsequent cardiovascular risk…” The Black Swan, Nassim Nicholas Taleb, Penguin Books, 2010, page 55.

See http://eurheartj.oxfordjournals.org/content/early/2011/05/27/eurheartj.ehr137.

Retrieved 14th June 2013.

See this article for a general overview:

http://boingboing.net/2012/01/10/tonsillectomy-confidential-do.html

[23] Darwin, Charles. The Descent of Man, First Edition (London: John Murray, 1871), Chapter I (page 27). Available at http://darwin-online.org.uk/content/frameset?viewtype=side&itemID=F937.1&pageseq=40.

With respect to the alimentary canal I have met with an account of only a single rudiment, namely the vermiform appendage of the caecum. The caecum is a branch or diverticulum of the intestine… It appears as if, in consequence of changed diet or habits, the caecum had become much shortened in various animals, the vermiform appendage being left as a rudiment of the shortened part… Not only is it useless, but it is sometimes the cause of death… this is due to small hard bodies, such as seeds, entering the passage and causing inflammation.

[24] This process is called convergent evolution.

[25] http://www.livescience.com/10571-appendix-fact-promising.html

[26] מסכת שבת דף עז עמוד ב: אמר רב יהודה אמר רב כל מה שברא הקב”ה בעולמו לא ברא דבר אחד לבטלה.

[27] מהר”ל תפארת ישראל פרק ח: וכבר אמרנו שאף אם אין ידוע לנו טעם וסבה של כל דבר ודבר שנמצא באדם למה הוא כך, מכל מקום ידוע לנו שאין דבר אחד לבטלה…

[28] A paper published in November 1999 in the journal Heart states that:

The physiological properties and anatomical relations of the LAA [left atrial appendage] render it ideally suited to function as a decompression chamber during left ventricular systole and during other periods when left atrial pressure is high. These properties include the position of the LAA high in the body of the left atrium; the increased distensibility of the LAA compared with the left atrium proper; the high concentration of atrial natriuretic factor (ANF) granules contained within the LAA; and the neuronal configuration of the LAA… Obliteration or amputation of the LAA may help to reduce the risk of thromboembolism, but this may result in undesirable physiological sequelae such as reduced atrial compliance and a reduced capacity for ANF secretion in response to pressure and volume overload. See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1760793/.

Retrieved 13th May 2013.

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