Monday, March 30, 2009
Wisdom Teeth
Humans have wisdom teeth, but it is clear that in today’s age there is no benefit of having these wisdom teeth come in, because our normal teeth do the job well enough. In fact, wisdom teeth coming in can actually be detrimental to other teeth. If this is true, why do we still have these teeth come up? Will humans lose these wisdom teeth over time? Discuss the loss of smell in humans and primates and how wisdom teeth might follow the same pathway. Also, is it possible that human actions are interfering with the process of natural selection to rid the human race from this harmful trait?
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As Sean Carroll mentions, "there are three elements of the evolutionary process- natural selection, sexual selection, and the descent of species with modification"(93). These three factors help us to explain why humans still have wisdom teeth. I believe that it is most unlikey for humans to lose wisdom teeth because natural selection is blind to it due to humans' improved technology. For instance, a lot of people feel pain when they have their wisdom teeth com in. If we dont have dentists, wisdom teeth may cause irregular arragnement of teeth, pain while eating, and eventually death. However, we have perfect solution for wisdom teeth, we can go to our dentist and he will take care of our wisdom teeth. Therefore, there is no natrual selection happening to humans because of our actions.
ReplyDeleteon the other hand, loss of smell in humans and primates shows differnt evolutionary pathway. Humans and primates have lost their sense of smell due to their evolution of color vision. Becuase of this evolution of color vision, primates didnt need strong sense of smell because we can identify predetors and foods just by looking at it.
I believe that humans will have wisdom teeth coming out forever because Natural Selection can not act on it and people do not care if thier wife or husband has wisdom teeth, therefore, we can not pass our modified genes to decendents.
Source:http://www.shvoong.com/exact-sciences/biology/1788907-evolution-primate-sense-smell-trichromatic/
It has been discovered that because of the diet of early humans, excessive wear was caused on our teeth and drifting of the teeth occurred leaving space for wisdom teeth to come up between the ages of 17 and 25. The diet normally consisted of course and rough food, nuts, leaves, and meats. In our diet today, we eat softer food and go to doctors to straighten our teeth therefore leaving less room for the wisdom teeth to come up, and when they do push through they cause problems by shifting the teeth currently in the mouth.
ReplyDeleteAnthropologists have now classified wisdom teeth as a functionless organ, and to lead to the problems, through evolution our mouths have become smaller in size. Therefore, we still have wisdom teeth because the early humans needed them to eat their diet and there has not been enough evolutionary time between that time in humans and today. Evolution take thousands of years to occur, so the disappearance of our wisdom teeth through natural selection will occur some day but in the future.
The smell ability in humans and primates have decreased over evolutionary history due to the loss of olfactory receptors in the nose. Anthropolgists believe that the loss of smell in humans in correlated to the gain of color vision because that became more useful to humans than a full sense of smell. I do believe that wisdom teeth will follow the same path as what has happened to our sense of smell because they are becoming less useful to use as a human population similar to the strong sense of smell.
I don't think that human actions are interfering with the action of natural selection of wisdom teeth because they will be removed through evolution gradually as the need for them decrease.
http://nimbleit.squarespace.com/simple-curiosity/2007/7/1/why-do-we-have-wisdom-teeth.html
http://anthropology.si.edu/humanorigins/faq/teeth.htm
http://scienceline.org/2007/02/05/ask-cooper-wisdomteeth/
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0020033&ct=1
We still have wisdom teeth because we have not had time to go through natural selection and get rid of them. Even 300 years ago, we did not have dentists that pulled these teeth out on a regular basis. Therefore, natural selection has not been able to see that we have no need for these teeth. According to Jackie, anthropologists have classified wisdom teeth as a functionless organ. This means that we literally do not use them at all. I know mine are growing in and I’m about ready to have them pulled, too! Although Carroll does state time and time again “if you don’t use it, you lose it”, but this process still takes time and is not a quick progression.
ReplyDeleteIt is interesting that some people are being born without wisdom teeth; so we can clearly see that natural selection is starting to work. Although most people are still born with them, many people are born without them and are part of “the next generation of humans”. Therefore, it is completely wrong to say that we are not evolving because people are beginning to lose the ability to develop wisdom teeth over time.
Although we are not exactly going through the natural steps of natural selection to get rid of wisdom teeth (i.e. having them removed by technology and not dying if you have wisdom teeth, as would probably happen in the animal world with some other trait), we are not killing the people that have the mutation against wisdom teeth. It is possible that we will end up half and half; some people having wisdom teeth and some people not. We may not fully get rid of wisdom teeth, but the fact that many people are being born without them is telling me that we are moving slowly to ridding the human race of wisdom teeth.
Humans are ENTIRELY interfering with the process of natural selection to rid the human race of this harmful trait, but it may not necessarily be a bad thing. We are not interfering with that fact that some are born without it and we are letting them reproduce and pass on their mutated genes. Thus, we will probably end up ridding the human race of wisdom teeth.
This relates to two biological themes; the relationship of structure to function and the theme of science and technology. First, the structure of wisdom teeth and where they lie makes it so that we have absolutely no need for them and thus no function for them. Although some people’s wisdom teeth do grow in correctly and they can actually be functional chewing teeth, most people absolutely do not need them. Although, in the past (millions of years ago…) humans did need them because of their coarser and rougher diet (according to Jackie, again ☺). Therefore, at some point, we did have a function for the structure of wisdom teeth, but now we really don’t need them and will most likely lose them. Likewise, this relates to the theme of science and technology because we are using technology to rid ourselves of this useless trait and are helping the human race get rid of this trait for good. The technological aspect of this is extremely important because we currently have braces and other things that help reduce the need for these useless “organs”.
This does relate to smell because we didn’t have a big enough need for a strong sense of smell and have gradually lost it over time. The same thing will most likely end up happening with wisdom teeth and that is okay because we really don’t need them. Therefore, there is a strong association between these two traits because they have become less and less useful and we are slowly ridding the human race of them.
http://answers.yahoo.com/question/index?qid=20071213184700AA9YsUU
I fully agree with Jessica that we are not interfering with the extinction of wisdom teeth because we don't kill those people who have them, which would an effective way of ridding the human population of the DNA in people who grow in wisdom teeth. Also, there are no environmental or biological affects of having or not having wisdom teeth because in our day and age we have the doctors and technology to remove wisdom teeth from our mouth therefore protecting all of our other teeth from being impacted. If the human population no longer produces humans with wisdom teeth this wouldn't cause any environmental or biological effect because we no longer need them to eat due to the fact that our diet has changed to softer foods than the hard foods that the early primates had to eat. Therefore, because the environment and our diet is changing to no longer need wisdom teeth to grind food, then through natural selection humans will be created without wisdom teeth because the environment is not favoring those who actually have wisdom teeth.
ReplyDeleteThrough evolution, our jaws have become smaller therefore allowing less room for the wisdom teeth. It has also been shown that the future and starting extinction of wisdom teeth in humans is not due to evolution but due to our switch to a softer diet and genetic mutations. In addition, it has ben shown that it is not beneficial to remove wisdom teeth unless they are causing a problem and should be treated like any other tooth in that they are only removed if impactment arises.
http://www.answersingenesis.org/tj/v12/i3/wisdomteeth.asp
http://yourtotalhealth.ivillage.com/wisdom-teeth.html?pageNum=3
I think you two are misunderstanding the difference between natural selection forcefully removing a trait and the relaxation of natural selection allowing a trait to become slowly fossilized. You are both correct in saying that wisdom teeth may some day be lost, but your reasoning is slightly skewed.
ReplyDeleteThe reason I wanted you to compare the loss of smell and wisdom teeth is because human’s sense of smell did not worsen because it was necessary to make that sense worse, but rather our survival simply did not depend on smell one way or the other. Under these circumstances, our sense of smell fell victim to the “use it or lose it” ideal presented by Carroll. This is where the key misunderstanding is. Those who had worse smell did not survive better than those with acute smell, but rather by chance our smell worsened, and selection was not present to monitor and correct this mutation. Because modern dentistry, this same pathway of “use it or lose it” fossilization is the only way in which wisdom teeth can now be removed. This might seem obvious, but if I better explain another possible pathway for the lose of wisdom teeth, it will be more clear what I was trying to hit at.
Wisdom teeth, as Sammy, Jackie, and Jessica have all confirmed, are not just useless to human beings but are damaging to human beings. This is a very significant difference. If they were useless, it would be obvious that they would take the slow, “use-it-or-lose-it”, fossilization path described above. If they are damaging, however, the scenario has completely changed. According to the properties of natural selection, this small difference in survival will be detected in the process of selection, and dealt over a long time by slowly filtering out wisdom teeth because they hurt the population. Since wisdom teeth are damaging, they affect the survival of those who posses the trait. When a trait actually affects survival or reproduction, it generates a negative selective coefficient. If a trait is completely useless, not affecting survival either way, it has a selective coefficient of 0. Let me conclude with how dentistry is overall affecting the method by which wisdom teeth are removed. Since wisdom teeth are damaging, they should produce a negative selective coefficient for that gene, so selection should act more quickly upon the difference and therefore more quickly remove the trait from humans. Dentistry completely removes this negative coefficient from the genes for wisdom teeth because they remove any effect that wisdom teeth might have on survival.
In the case of wisdom teeth, it really doesn’t matter whether we lose them in 1,000 years or a few million years (if humans or descendents of humans still exist), but it is a good example of showing how human civilization has affected the evolution rates of both humans and other species. In other cases, however, our actions can be more harmful, for example, infectious organisms that evolve quickly to chemicals. In the case of malaria, we were severely affecting the selective coefficient on many genes in malaria-causing parasites because when we administered chemicals that virtually killed all these parasites, maybe one in thousands survived due to a mutation making the selective coefficient here extremely high, speeding up evolution possible 1,000-fold.
http://www.malariasite.com/MALARIA/DrugResistance.htm
Wisdom teeth, commonly called the third molar because it comes it later and is not really needed in present day procedures. They came in because early diets caused excessive wear on the teeth and usually the loss of several teeth. This then gives in room for the wisdom teeth to come in when they did between the ages of 15-25 with no problems, but actually help the early humans. They are now thought of as a functionless organ, because with modern healthcare and dieting there is no need for them, but they still will exsist because there is still genetic code for them. If the wisdom tooth does come in, and causes problems the dentist remove it either if the wisdom teeth have already become impacted, or the wisdom teeth could potentially become problematic if not extracted. Potential problems caused by the presence of properly grown-in wisdom teeth include infections caused by food particles easily trapped in the jaw area behind the wisdom teeth where regular brushing and flossing is difficult and ineffective. Such infections may be frequent, and cause considerable pain and medical danger. Other reasons wisdom teeth are removed include misalignment which rubs up against the tongue or cheek causing pain, and orthodontics. Myself going through this painful process believe they are not needed, and should be removed by dentists. I don’t think that wisdom teeth will ever be removed by natural selection and evolution, just like how the appendix hasn’t been removed by evolution even though in present times there is no need for it.
ReplyDeleteI have noticed larger amounts of people who do not have wisdom teeth ever come in their life, but I still think that they are just lucky. I believe that since people with wisdom teeth are getting them removed, they still have the genes that code for them, and when they have children they still pass the code down. Wisdom teeth are not a selective advantage , they are considered as useless organ, because they are no longer used; however humans do not pick to marry someone depending on if they have wisdom teeth or not. Therefore the genes are being passed down and humans will not be able to evolve away from wisdom teeth unless they bring about immediate death and only people without them continue on living.
The loss of smell in humans and primates for a full color vision is because full color vision lets differentiation occur much quick than smelling something. Full color vision was more important and was being used more, so it led to the decrease of olfactory receptors in the nose. This less olfactory receptors leads to weaker sense of smell and creating a larger reliance on the eye sight. Because of this evolution of color vision, primates didn’t need strong sense of smell because we can identify predators and foods just by looking at it. I don’t think wisdom teeth will follow the path of natural selection because humans always intervene in it, by preventing pains and disease by fixing the problem. If natural selection were allowed to act people with problems would be let to die and then it could possibly be created that wisdom teeth and other useless organs would be eliminated. This will not happened to wisdom teeth because of the interventions humans have with their body and fix all their problems. Genetic code for the teeth will keep being passed down and will not be eliminated.
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