Sunday, March 27, 2011
Talk Is Not Cheap
On page 189, Shubin discusses the price that humans have to pay for talking. What are some of the problems that humans face due to talking? Discuss how organs of the respiratory and digestive system may cause some of these problems. How does this price of talking relate to the larger theme of "why history makes us sick" or how evolution has caused some of these problems? Hannah Kay (hgkay@aol.com)
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Probably the biggest price humans must pay for talking is sleep apnea, as Shubin discusses on page 189. This is because is “between twelve and twenty million Americans suffer from sleep apnea to some degree” and “roughly 38,000 cardiovascular deaths annually are in some way related to sleep apnea” (http://www.apneaguide.com/sleep-apnea-statistics/). Sleep apnea is caused by our throat muscles relaxing when not in use (as in not talking) and can prevent breath. This, of course, is an evolutionary disadvantage- a drawback to the major advantage of communication. Other animals with highly evolved communicative skills, such as dolphins, do not have the problem of sleep apnea because they do not have vocal chords like humans. Instead they communicate with a complicated system of trills, clicks, squeaks, and moans—bypassing the sleep apnea problem altogether. (http://www.beach-net.com/dolphins/communication.html).
ReplyDeleteAnother problem the evolution of talking has led to for humans is choking. (This is not the biggest problem as it only leads to about 31 deaths per year in the United States. http://phoenix.about.com/od/phoenixfactsandfiction/a/accidentaldeath.htm.) The mouth serves as the place of release for the product of our vocal chords, in addition the entrance for our digestive system. This structure of a hole (or sphincter) leads to its function for both these uses. However, this being the case, food can occasionally “go down the wrong pipe” and become lodged in the trachea rather than the esophagus- which leads to choking. Certainly death is never an evolutionary advantage, so one may ask why would the mouth serve these two functions if it may lead to death? As Mr. Carmichael, my accelerated biology would say, because it works! But truly, it was more of an evolutionary advantage to talk and breathe with a trachea than the risk posed in using it. So this structure led to advantageous functions.
By the way, Hannah, your title is cute for this blog post.
(Jackie Edelson, jedelson92@gmail.com)
As Jackie mentioned above, sleep apnea is one of the biggest prices humans pay due to our ability to talk. Sleep apnea usually occurs during sleep, when the muscles in our throat that are used for talking are relaxed, therefore leading to long stretches of time without breathing. This is a disadvantage that comes along with the ability of talking because there is not enough oxygen that enters the lungs during sleep, therefore disrupting proper breathing while sleeping. This can occur because of the flexibility of human throats, which, according to Shubin, are "so useful in our ability to talk" (189). Jackie also states that sleep apnea is an evolutionary disadvantage for humans and that other animals with highly evolved communicative skills can avoid suffering from sleep apnea. Although this may be true in the case of dolphins, other animals such as persian cats and bulldogs (which also have their own communicative skills, although not as developed as humans) can suffer from sleep apnea. Animals such as cats and dogs have the ability to communicate (although not as sophisticated or complicated as the communication system of humans and dolphins) with each other and have voice boxes that give them the ability to make sounds (barking or purring, which is almost the cat/dog equivalent of talking). Because these animals have voice boxes and are able to make sound, the possibility of such animals getting sleep apnea is not unheard of. There are instances where young cats and dogs have died due to sleep apnea, which is similar to sudden infant death syndrome in humans.
ReplyDeleteChoking is another cost of being able to talk. Because the mouth leads to the trachea and the esophagus (the first for breathing and the latter for eating), "we use the same passage to swallow, breathe, and talk" (189). If food were to get stuck in the wrong passageway (the trachea instead of the esophagus), then choking would occur. This also cuts off the oxygen that goes to our lungs and if the food is not removed from the trachea in a certain amount of time, can lead to death. This is the result of evolution over generations as the human digestive and respiratory system has developed in this way.
Sujin Ko (sujinko93@gmail.com)
Sources: Shubin
http://en.wikipedia.org/wiki/Sleep_apnea
http://causesofsleepapnea.org/
http://www.sleepandhealth.com/do-animals-have-sleep-disorders
http://www.sleepandhealth.com/topics/story-topic/apneas-amp-respiration
In addition to the problems of choking and sleep apnea that Jackie and Sujin mentioned, there are other dangers that are caused by being able to talk. For example, due to the evolution of the vocal tract, 500,000 people today suffer from swallowing disorders such as dysphagia (Lieberman, P). These can be very dangerous and even fatal. There is also a greater risk of a blocked larynx due to the evolution of vocal chords (Lieberman, P). Another problem posed by the evolution of speech and vocal chords is the possibility of food falling into the lungs (Bolles, E). The cause of this danger is that the larynx has lowered over time in order to produce different frequencies of sound. Therefore, this danger is a trade off for being able to make a variety of different sounds.
ReplyDeleteThis relates to the idea of evolution causing problems because we descended from organisms, such as fish, that didn't have the ability to talk. Only recently in evolutionary history have animals been capable of speech. Therefore, we have to modify old body parts and use them in new ways. We also have to deal with obstacles or dangers that come with modification of these body parts. If we had evolved from ancestors that did talk, we would have inherited a throat structure more favorable for speaking, with more advantages for complex vocal chords, and without the disadvantages, such as the risk of choking or inheriting swallowing disorders.
Sources:
http://www.babelsdawn.com/babels_dawn/2010/10/the-evolution-of-the-vocal-tract.html
http://www.cog.brown.edu/people/lieberman/pdfFiles/Lieberman,%20P.%20&%20McCarthy,%20R.%202007.%20Tracking%20the%20evolution%20of.pdf
Marissa Lobl (marissa.lobl@gmail.com)
In addition to sleep apnea, dysphagia, and choking, which were discussed by Jackie, Sujin, and Marissa, having a stigmatism or lisp is also a problem that humans face when talking. Although the cause of lisps varies among individuals, swollen adenoids or tongues can lead to developing a lisp. The adenoids are located in the back of the nasal cavity, and are part of the immune system. Adenoids stop growing by age 7, and incidentally, children form speech impediments early on, before the age of 7. Although adenoids help to prevent infection, they become swollen after being infected by bacteria or viruses. Even after the body has finished fighting the infection, some peoples’ adenoids remain enlarged, resulting in a speech impediment. The adenoids can be removed, but this increases a person’s chance of their speech becoming even more nasaly. This occurs because the gap between the soft palate and the roof of the mouth no longer closes correctly after they are removed. Lisps can often be treated using speech therapy. This realates to the biological theme of structure and function, there is some sort of abnormality in a person’s mouth that results in a lisp. If certain body parts are too large or small, this creates a noticeable difference in a person’s speech. (http://www.patient.co.uk/health/Tonsils-and-Adenoids.htm)
ReplyDeleteLaryngitis is another condition caused by talking too much. The vocal cords we use to talk are located in the larynx, by vibration and air passing through these cords. Laryngitis is caused by inflammation of the vocal cords, as a result of infections, using your voice too much, or inhaled irritants. Laryngitis often results in a horse voice. Laryngitis can be prevented by drinking enough water to keep the mucus in the throat moist and thin and not smoking, because smoking dries out and irritates the vocal cords. (http://stanfordhospital.org/clinicsmedServices/clinics/otolaryngology/laryngology/patientEducation/vocal.html, http://www.mayoclinic.com/health/laryngitis/DS00366/DSECTION=prevention, http://www.urmc.rochester.edu/encyclopedia/content.cfm?pageid=P00475)
Anna leng (annaissbananas@yahoo.com)