Posts Tagged ‘organs’

useless human body parts

There is this great misconception today that the human body is covered with useless organs. Blogs, youtube videos and scientific news sites frequently release the top 5, top 10, or top 20 most useless human organs or body parts. It makes for fun reads and as interesting as the topic is, all these sources are incredibly misleading because most of the organs they mention actually do have a function. Some, incredibly important functions.

So here is my rebuttal to the top 10 most useless human organs:

Plica semilunaris:

The plica semilunaris is that tiny fold of pink tissue in the corner of your eye where your little eye crusties tend to collect. According to many authors who believe this tissue is useless, they speculate that it is the remains of a third eyelid or nictitating membrane that many of our distant ancestry utilized and other animals use today, but that it is essentially functionless for humans.

This is not the case though. According to ophthalmologist Peter Gurney, the plica semilunaris enables unrestricted movement of the eye when turned outward, stretching and contracting to allow the eye ball and eyelids to move independently of each other when the eye looks side to side (Gurney, 99). Other studies suggest that the plica semilunaris secretes an agent that binds with free particles caught in your eye, coating them and minimalizing any scratching damage the particles may cause.

anat eye

Darwin’s point (tubercle) (extra skin flap on ear):

Darwin’s point, aka Darwin’s tubercle, aka the extra skin flap on your upper ear, is often mentioned as a useless part of the human body that is a throwback to some early ancestor that allowed the top of the ear to swivel or flap down over the opening. According to Dr. David Dewitt, professor of biology at Liberty University, the extra skin flap is a “harmless congenital defect” resulting from a malformation as the ear folds during early development only found in about 10% of humans (Dewitt).  In this case, the flap is indeed functionless, but the claim that the flap once had a function and no longer does is not correct. The flap is a random trait no different from other dominant traits (like a widow’s peak) which don’t serve a purpose, but were never supposed to in the first place.

Body Hair:

Body hair is a very popular example of a supposed useless organ because we tend to associate it as a sparse remnant of fur seen on apes which use it for warmth, sun protection ect. It is a fair question to ask;  why do we need facial hair, chest hair, leg hair, etc. ?

Dr. David Menton, retired professor of anatomy at the Washington School of Medicine and contributor to Stedman’s Medical Dictionary, points out that the difference between the dense hairs on apes and our sparse hair is related to our sweat glands. If our hair was too dense the water from our sweat glands would not be able to evaporate and we would not be able to keep cool. As far as purpose, the hairs are attached to several nerve endings that act as sensory receptors (called mechnoreceptors) which helps us detect motion and object proximity (Menton, 238-239). In addition, a recent study completed at the University of Sheffield in England found that body hair aids in fending off parasites and insects that land on our body. On one level it stimulates nerve endings letting us know a creature has landed on us. On a second level the hair provides a larger surface area prolonging the time required for the creature to get to our skin, allowing us enough time to swat the creature away (Hooper). But the most important function of hair and hair follicles is reepithelialization, in which in the event of a cut or abrasion hair follicles act as a source of epidermal cells for the skin to utilize for restoration (Menton, 239). If it wasn’t for hair follicles skin repair after injury would be impaired.

Vomeronasal Organ:

The vomeronasal organ (aka Jacobson’s organ) is a sensory organ associated with smell that many mammals have and utilize, but it is said that humans don’t use it. The vomeronasal organ is a chemoreceptor organ that responds to nonvolatile cues which in turn activates locations of the hypothalamus that regulates reproductive, defensive, and ingestive behavior along with neuro-endocrine secretion (Keverne, 716). This organ is present in humans, so the question is, do humans use it? A study  completed by Oxford University found evidence that indeed it may be used, and though usage may be minor it is not insignificant (Meredith, 433). Though the study is cautious to say more experimental testing is required to reach a final conclusion.

Wisdom Teeth

Wisdom teeth (or third molars) are considered a useless body part because there does not seem to be any room for them on the jaw. Hence, they are often removed, as I’m sure many of you readers can attest to. But, there not being enough room on the jaw is not always the case for everyone. In fact, when people do have sufficient room on their jaw the wisdom teeth operate as fully functional molars used just as much as the first and second molars (Menton, 236). So why are some jaws too small to house the third molars? One reason is diet. In less developed countries diets are coarser, where in more developed nations the diet consists of softer foods (Bergman, 297). Coarser foods can influence the jaw to widen, which in turn creates the room necessary for the third molars. Other factors come into play as well, but the point is that they are not useless for everyone, only on those with small jaws.

In America it has been estimated that only 20% of all young people develop impacted molars and actually need them removed (Menton, 236),  but most Americans have them removed because the outdated consensus within the dental community is that they are useless and only run a risk of impacting the rest of your teeth. So it is better to play it safe and have them removed. Whether the dentists are right or wrong in doing this is not in question here, it is the use of the teeth that are in question, and it is certainly true that wisdom teeth are not useless.

Auricular muscle

The auricular muscle is a muscle attached to your ear that some people can stimulate to make their ears twitch. It is considered useless because it is thought to be a remnant of a more developed muscle that other mammals have which allow them to rotate their ears around much like cats, deer, etc. The problem is that most people consider muscles for only one use: movement. But movement is not the only role muscles can serve in the body. Some muscles in our body serve as sensory muscles while others, like the auricular muscle, serve as formation and positioning muscles, whose job it is to not necessarily move an appendage, but allow the appendage to form and be held in place.

This is nothing new however. A 1970s study from the University of Washington School of Medicine found that the auricular muscle serves a role as the foundation for cartilaginous pinna development and positioning (Smith and Takashima). That is, the auricular muscle ensures your ears develop and are held in position properly. For example, deformations of the auricular muscle lead to abnormalities known as “lop” ear. In fact, many defects of the ear can be linked back to muscle abnormalities surrounding the ear.

anat-Auricularis_superior

Coccyx (tail bone)

We’ve all heard that our tail bone is useless, or a throw back to when we had tails. It seems simple enough, we have this tail like bone structure, but we have no tail… how useless! This is actually very incorrect. The coccyx is an anchoring point for many muscles. The levatorani muscle group for example, attaches to the coccyx and plays a very important role of supporting the pelvic floor and maintaining fecal continence (www.coccygectomy.org). Other muscles that anchor to the coccyx are the anococcygeal raphe used for support of the anus and the gluteus maximus which facilitates a wide range of body movement from the waste down. Dr. Menton writes, “The incurred coccyx with its attached pelvic diaphragm supports the organs in our abdominal and pelvic cavities such as the urinary bladder, uterus, prostrate, rectum and anus. Without this critical muscular support, these organs could be easily herniated,” (Menton, 238).

So clearly the bone not only serves a function, but its function is vastly different from the function that a tail provides for other mammals. Dr. Menton writes, “The coccyx is commonly called the ‘tailbone’ because of its superficial similarity to a tail. The coccyx does occupy the same relative position at the end of our vertebral column as does the tail in tailed primates, but then where else would it be? The vertebral column is a linear row of bones that supports the head at one end and the other must end somewhere,” (Menton, 237).

anat coccyx_lg

Erector Pili

The erector pili are small muscles that give us that goosebump look when we’re cold and scared. The general idea of these muscles are that in the event of conflict, the pili engage causing our hair to stand on end, something many mammals do to appear larger or more intimidating. In the event of cold weather or chills, the pili engage causing the hair to rise trapping more air and creating additional insulation to keep the body warm. Both functions, for warmth and intimidation, are both considered useless on humans due to our lack of sufficient hair.

Yet, there are actually two functions the erector pili still provide to humans. The pili are positioned to help squeeze oils from the various sebaceous glands on our bodies, allowing the oils to secrete onto the skin surface (Menton, 239). This oil, called Sebum, provides Vitamin E, antioxidants and anti-microbal lipids to the skin. Additionally, even though our body hair can be sparse, goosebumps still do generate heat on our body and are still useful as an initial reflex in keeping us warm. Though this warming effect may not nearly be as effective as it is with hairier mammals, it is still a useful function. Plus, if you recall, it is a trade off for our ability to sweat and cool off during warm weather.

The Appendix

The appendix is a well known organ because of the risk it poses of bursting and killing us. Its function is, however, rarely publicized. In the past it was criticized as a useless organ that once served a purpose for digesting food. However, in more recent years it is being widely acknowledged as a major player in our immune system. The tissue lining the inside of the appendix has been found to make antibodies (Leyner & Goldberg, 64). Further research revealed that the appendix also serves as a “safe house” for storing bacteria used in the intestine for digestion. In fact, in the event of a pathogen making its way into the intestine, beneficial digesting bacteria are often lost in the ensuing purge. The appendix however replenishes the intestine with bacteria after just such an incident (Bolinger). Can you live without the appendix? Yes. But at great cost to your immune system. People who lose their appendix are more susceptible to acquire viruses like Hepatitis C.

Male Nipples

The number one cited useless organ has to be male nipples. It seems so obvious. Men do not need nipples. They are useless. And unlike other claimed useless organs, I make no argument of use for male nipples. They are indeed useless.

Where I will make an argument is the inference people draw from the uselessness of the nipples. Whatever your philosophical reasoning is for why men have nipples, the truth is that the purpose of all nipples is for breast feeding to rear young. But I’m sure you’re thinking, men don’t breast feed! Yes, men don’t breast feed, but females do. Well, during embryonic development our bodies follow a female template for about six weeks, after which, if you are to be a male, the male sex chromosome kicks in and male characteristics develop (Leyner & Goldberg, 61). In the same way, a female’s ovaries and a male’s testicles were originally the same organ, called gonads, before sexual differentiation.

 

Closing Thoughts

I hope you can see now that many of the organs that are claimed to be useless actually do have a use. Granted, many of these uses were not identified for a long time, which led to the misnomer that they were functionless. This leaves me skeptical of other and future accusations for useless organs whether on humans or other animals. As Mention points out, “The problem with declaring any organ to be without function is discriminating between truly functionless organs and those that have functions that are simply unknown. Indeed, over the years nearly all organs once thought to be useless have been found to be functional. When we have no evidence for function of an organ, we need to bear in mind that absence of evidence is not evidence of absence,” (Menton, 231).

Additionally, I’ve heard many people argue that an organ is useless simply because you can live without it. Wisdom teeth and the appendix are common examples. People have them taken out every day and are just fine… sort of. This argument is poor because it equates organ use to mere survival. You can technically live with no eyes. You can technically live with no legs. If you went into surgery to have your ears removed you could live without them. But your abilities will obviously be greatly impaired. In the same way, you may be able to live without any of these ten organs I listed, but at what cost?

A great example is the coccyx (tail bone). Brandon Miller, a contributor to live science and convinced that the coccyx is an evolutionary leftover writes, “It has been suggested that the coccyx helps to anchor minor muscles and may support pelvic organs. However, there have been many well documented medical cases where the tailbone has been surgically removed with little or no adverse effects,” (Miller). Miller  ignores the “suggested” notion that the coccyx has a purpose simply because of the lack of profound adverse effects if you have it removed. Yet medical sources that discuss the removal of the coccyx warn of the draw backs to the procedure. A common complaint among patients that have had it removed is the sagging of pelvic contents and fecal incontinence (Lakshmanan). And as Menton mentioned earlier, hernias are much more common in the pelvic region as well with the tail bone being removed. Whether you consider these drawbacks “minor” is irrelevant to the argument of function.

The last point I’ll discuss is the term vestigial, which is applied to many of the organs listed as useless. A vestigial organ is an organ surviving and remaining in a degenerate or imperfect condition or form (Miller). So an organ may have function, but because it is believed the organ once had greater function, it can be considered vestigial. This is precisely the problem I have with this term: How can we know an organ once had greater function? All claims would fall under the category of speculation. It seems that many people are failing to acknowledge a very reasonable and obvious notion: Perhaps these organs have always had the functions they continue to have. Yes, the  auricular muscle and vomeronasal organ may have minor uses we could live without, but these uses may have always been at their functional limit. Pointing out other mammals with similar organs used to a higher degree to argue the vestigial nature of our organs only works within an macroevolutionary worldview. It does not objectively provide any conclusive evidence on its own because it is circumstantial evidence. In other words, evolution must be assumed first, before vestigial organs can be used as evidence for the evolution. It is a circular argument: The vestigial organs prove evolution, evolution proves those are vestigial organs. As Dr. Dewitt concludes, “They [vestigial organs] are evolutionary relics of common ancestors with animals only if you begin with evolutionary presuppositions,” (Dewitt).

So next time you read of useless organs and evolutionary left overs just remember that most of the claims are outdated with origins that are exaggerated and speculated.

References:

“What is a coccyx and what does it do?” www.coccygectomy.org, accessed 10-06-2013.

Bergman, J., (Dec 1998) “Are wisdom teeth (third molars) vestiges of human evolution?” Journal of Creation, 12(3).

Bollinger, R.R., (2007) “Biofilms in the Large Bowel Suggest an Apparent Function of the Human Vermiform Appendix,” Journal of Theoretical Biology, 249 no.4, pp. 826-831.

Dewitt, D.A., (May 28, 2008) “Setting the Record Straight on Vestigial Organs,” www.answersingenesis.org accessed 10-06-2013.

Gurney, P., (December, 2001), “Dawkin’s eye revisited,” Journal of Creation, 15(3)

Hooper, R., (Dec 14, 2011) “Hairier is better- bedbugs bite our barest bits,” www.newscientist.com, accessed 10-06-2013.

Kevern, E.B., (Oct 22, 1999) “The Vomeronasal Organ,” Science, 286(5440).

Lakshmanan, P., (Aug 23, 2013) “Coccygectomy,” emedicine.medscape.com, accessed 10-07-2013

Leyner, M., & Goldberg, B., (2005) Why Do Men Have Nipples?  (New York, NY: Three Rivers Press)

Menton, D.N., (2010) “Vestigial Organs- Evidence for Evolution?” as written in Ken Ham’s The New Answers Book 3, (Green Forest, AR: Master Books)

Meredith, M., (May, 2001) “Human vomeronasal organ function: a critical review of best and worst cases,” Chem Senses, 26(4).

Miller, B., “Top 10 Useless Limbs (and Other Vestigial Organs),” www.livescience.com, accessed 10-07-2013

Smith, D.W. & Takashima, H., (1978) “923 Ear Muscles and Auricular Anomalies,” Pediatric Research, 12.

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