Tuesday, April 14, 2009
Human genetic decay and technologies
On page 105 Carroll states that up to 8 percent of color blindness occurs in Caucasian males while only 3 of 3153 tested macaque monkeys from the wild (<.1%) were color blind. This disparity demonstrates how in many cases humans are not under the preservative forces of natural selection. Instead, humans have succumbed to comfortable living and do not struggle with daily life or death situations in nature, or at least for most humans. In addition many new technologies are allowing humans to overcome selectively disadvantageous mutations that are then passed on to successive generations and allowed to circulate populations. Under the relaxation of the pressures of natural selection, will the human genetic code begin to decay and express a excessive amount of fossilized genes similar to the Mycobacterium leprae, a microbe that has compromised its independence due to specialization of living in host cells and has 1,100 fossil genes? As well list technologies that have given humans the ability to surpass the restriction of a disadvantageous mutation as well as that specific mutation. Are these technologies benefiting or damaging the human race? Is this no longer survival of the fittest?
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Tuesday, April 14, 2009
ReplyDeleteHuman genetic decay and technologies
On page 105 Carroll states that up to 8 percent of color blindness occurs in Caucasian males while only 3 of 3153 tested macaque monkeys from the wild (<.1%) were color blind. This disparity demonstrates how in many cases humans are not under the preservative forces of natural selection. Instead, humans have succumbed to comfortable living and do not struggle with daily life or death situations in nature, or at least for most humans. In addition many new technologies are allowing humans to overcome selectively disadvantageous mutations that are then passed on to successive generations and allowed to circulate populations. Under the relaxation of the pressures of natural selection, will the human genetic code begin to decay and express a excessive amount of fossilized genes similar to the Mycobacterium leprae, a microbe that has compromised its independence due to specialization of living in host cells and has 1,100 fossil genes? As well list technologies that have given humans the ability to surpass the restriction of a disadvantageous mutation as well as that specific mutation. Are these technologies benefiting or damaging the human race? Is this no longer survival of the fittest?
Answer:
The human genetic code, just as well as how the genome of any organism would react to relaxed selection, would express more fossilized genes in response to the relaxation of the pressures of natural selection. We are already seeing evidence of this in humans such as the growing cases of color blindness in males, worse hearing, and suppressed immune systems. We live in a world of technology that no longer requires us to rely on our primital senses to acquire food for survival. We don’t need to hear to escape predators. Hearing has become something we use for pleasure (i.e. listen to iPods, listen to radio) rather than necessary for the survival of the human race. We are using more and more antibacterial soaps that are causing an epidemic in allergies, asthma, and suppressed immune systems according to the Hygiene Hypothesis but we can surpass this problem with medicine and therapy that can treat these genetic problems. Ironically, technology might actually lead to the destruction of the human race because it is relaxing the pressures needed for natural selection, therefore causing people with more and more problems to be born.
An obvious technology that has given humans to surpass a disadvantageous gene is glasses, contacts, or even laser eye surgery. These things can correct our vision even if we were born with bad eyes. Eye glasses’ corrective lenses are shaped to correct various vision abnormalities such as myopia. Newer plastic lenses, called izon, can also correct for the higher order aberrations that naturally occur in the surface of our eye. These lenses create sharper vision and help with the halos, starbursts, and comet-tails often associated with night time driving glare. We no longer are limited by bad eyesight. LASIK is a surgical procedure intended to reduce a person's dependency on glasses or contact lenses. So the technologies used to help our sight are now even being replaced by correcting our eyes themselves. It can treat astigmatism, hyperopia, and other problems by improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.
Another one of these technologies is hearing aids. It makes some sounds louder so that a person with hearing loss can listen, communicate, and participate more fully in daily activities. A hearing aid can help people hear more in both quiet and noisy situations. They are primarily useful in improving the hearing and speech comprehension of people who have hearing loss that results from damage to the small sensory cells in the inner ear, called hair cells. This type of hearing loss is called sensorineural hearing loss. The damage can occur as a result of disease, aging, or injury from noise or certain medicines. With this technology, people can surpass hearing problems.
These technologies are both benefitting and damaging the human race. From one point of view, people who were born with genetic problems can surpass that and press themselves to achieve greater things without being limited because of their genetic history. These people are a useful and integral part of society and can not be just removed. However, the more we rely on these technologies to help us surpass our problems, we are actually damaging the human race altogether. Instead of natural selection weeding out those who are weak and sick to build up a strong and healthy race, more and more genes are getting passed from people who have diseases therefore having the overall human race getting less and less healthy. We have stopped moving forward in terms of genetics and in order to make the world better for people with disabilities or diseases, we are making it worse for the human race.
http://en.wikipedia.org/wiki/Glasses
http://www.fda.gov/cdrh/LASIK/
http://www.nidcd.nih.gov/health/hearing/hearingaid.asp
Human genetic decay and technologies
ReplyDeleteOn page 105 Carroll states that up to 8 percent of color blindness occurs in Caucasian males while only 3 of 3153 tested macaque monkeys from the wild (<.1%) were color blind. This disparity demonstrates how in many cases humans are not under the preservative forces of natural selection. Instead, humans have succumbed to comfortable living and do not struggle with daily life or death situations in nature, or at least for most humans. In addition many new technologies are allowing humans to overcome selectively disadvantageous mutations that are then passed on to successive generations and allowed to circulate populations. Under the relaxation of the pressures of natural selection, will the human genetic code begin to decay and express a excessive amount of fossilized genes similar to the Mycobacterium leprae, a microbe that has compromised its independence due to specialization of living in host cells and has 1,100 fossil genes? As well list technologies that have given humans the ability to surpass the restriction of a disadvantageous mutation as well as that specific mutation. Are these technologies benefiting or damaging the human race? Is this no longer survival of the fittest?
As for similarities between Mycobacterium leprae and humans, a big difference exists. First of all mycobacterium leprae is the microbe that causes leprosy, a chronic human neurological disease which affects the peripheral nerves, mucosa (the lining of the nostrils, lips, ears, genital areas, and anus) of the upper respiratory tract, and skin. If the microbe was to continue to infect the body without any source of treatment, leprosy can cause permanent damage to the skin, nerves, limbs, and eyes. It’s been around for a very decent amount of time affecting mankind since at least 600 BC. The microbe takes the longest to double through binary fission.
In the process of binary fission chromosomes replication first begins and not before long one copy of the origin moves toward one end of the cell. The replication continues when one copy of the origin is at each end of the cell. When replication finishes the Plasma membrane grows inward, and new cell wall is deposited. Thus resulting in two daughter cells.
This long process of duplication for the mycobacterium isn’t the only thing stopping researcher’s study of the fascinating microbe that inflicts so much pain upon the world. The microbe’s DNA demonstrates an extreme version of gene fossilization with less than half of the genome actually containing functional genes. Gene decay and fossilization has destroyed many important metabolic activities including “siderophore production, part of the oxidative and most of the microaerophilic and anaerobic respiratory chains, and numerous catabolic systems and their regulatory circuits.” This lack of functional genes that allow it to live on its own makes it extremely difficult for researchers to culture the microbes in a petri dish and study. The genome destruction is attributed to extensive recombination events between dispersed repetitive sequences.
The slow doubling time is due to the fact for the restricted intake of nutrients through the pores in the large waxy walls which is attributed to the unique lipid wall that makes up the membrane. The large hydrophobic shell prevents polar molecules, such a medicine, from entering the cell.
The primary source of ATP is from the Krebs cycle and from the host, where as its own electron transport chain which usually provides the most amount of energy for a cell’s needs is extremely restricted and shows how M. leprae has evolved into a parasite. All in all, I refuse to believe the microbe is at a disadvantage in the world. The microbe has adapted its own way to living in order to survive in the current environment. Matt, I think you characterize DNA decay as a bad thing. Usually DNA decay occurs because it is a selective advantage and will benefit the creature in the near future. Think about the monkey who had his opsin genes fossilized. True, he lost the ability to see the real wonders of the world in color, but it allowed him to see in black and white. It allowed him to survive with his nocturnal habits with his sharp contrasts in the dark in order to seek out food and escape predators.
And to address Julia’s theory of human’s declining. Is our hearing really that bad? Did we really even lose that or were we not even genetically modified like that in the first place? We are born with extremely sensitive hearing and we should be able to hear between 20Hz and 20 kHz. Our ability to hear deteriorates not from genetic decay but from physical use. Tiny hairs in our ear begin to fall or die off making it less sensitive to the sounds around us. So technically those hearing aids are not typically affecting the gene poorly rather than just amplifying sounds so that a deafened person can hear once again.
I also really question if Lasik surgery is a technology that impedes genetic development. Near and farsightedness is due to the fact that the muscles are unable to adjust the focus so it requires the help of some glass lens. The real technology that I feel that impedes our genetic development is medicine. Antibiotics especially are really ruining our chance to adapt to the environment. Antibiotics only create super bugs that are extremely immune to all medications which will eventually be the ruin of all humankind as these bacteria get stronger and stronger as we become more static.
That’s beside the point. I feel that the meaning “fit” is completely subjective. We’re no longer savages that require raw brute force to hunt animals in order to feed ourselves. We no longer need super senses to sense our prey and feed out young. Our situations have changed. WE require more intelligence and more innovations in order to survive. Doctors, scientists, and teachers usually aren’t built like a football player but they are really who push society and life along. We need more ideas, wit, and knowledge to truly compete in the world we live in now.
http://en.wikipedia.org/wiki/Mucous_membrane
http://en.wikipedia.org/wiki/Leprosy#Cause
http://microbewiki.kenyon.edu/index.php/Mycobacterium_leprae
http://www.ncbi.nlm.nih.gov/pubmed/11234002
http://www.newworldencyclopedia.org/entry/Hearing_(sense)#Hearing_in_humans
An example of technology that has given humans the ability to surpass the restriction of a disadvantageous mutation would be an artificial pacemaker. An artificial pacemaker is a medical device that takes over the function of the natural cardiac pacemaker. It uses electrical impulses that are carried by electrodes that regulate the contraction of the heart muscles as well as the beating of the heart. A pacemaker uses batteries to send electrical impulses to the heart to help it pump properly. An electrode is placed next to the heart wall and small electrical charges travel through the wire to the heart. The purpose of an artificial pacemaker is to stimulate the heart when either the heart's native pacemaker is not fast enough or if there are blocks in the heart's electrical conduction system preventing the propagation of electrical impulses from the native pacemaker to the ventricles. This technology was extremely beneficial to the human community because it was a way to solve the problem with the regulation of the heart. The technology is beneficial towards humans but it is preventing nature keeping the human race “fit” and the so called “survival of the fittest”.
ReplyDeleteAnother example of a technology that has given humans the ability to surpass the restriction of a disadvantageous mutation would be asthma inhalers. Asthma is a chronic lung disease that constricts the airways. It is rapidly increasing and it is affecting 1 in 4 children. Some triggers of asthma are environmental as well as genetic factors. There are many different types of asthma and how it can occur. One way is bronchoconstriction, which is when inflamed airways react to environmental triggers such as smoke, dust, or pollen. The airways narrow and produce excess mucus, making it difficult to breathe. The airways are very hypersensitive. Another possible cause for asthma is Bronchial inflammation. Asthma can be the result of irritation from pollen and other allergens. The allergens that are inhaled are engulfed by Antigen presenting cells or APCs . APC’s then "present" pieces of the allergen to other immune system cells. In most cases this is not a problem because Helper T cells usually check and ignore these foreign allergens. In people with asthma, they the helper T cells usually transform into other type of cells such as TH2 cells. The resultant TH2 cells activate the humoral response. The humoral immune system produces antibodies against the inhaled allergen. In the second exposure to the allergen, the antibodies respond to it activating the humoral response. Soon, inflammation occurs and chemicals are produced that cause the airways to thicken to not let any more allergens get in. This causes mucus cells get bigger and produce thicker mucus. This makes it harder for the person to breathe. Asthma inhalers are used then to reopen the airways. This can be due to a mutation in a copying the genes. This is a selective disadvantage because these people are under constant risk having their airways constricted. If this was in nature then the people that have been affected with asthma cannot run far distances or away from predators. Here natural selection is taking place and only the fittest will be able to survive. However, there is medication in the form of asthma inhalers.
This is no longer the survival of the fittest because there are many new technologies to help keep humans alive and function as normal people. This is good for the human race because the value of a human more to us now. However, for nature this is bad because this is not following the direct pathway of natural selection. This is no longer the survival of the fittest. It all based on technology.
http://en.wikipedia.org/wiki/T_helper_cell
http://en.wikipedia.org/wiki/T_helper_cell
http://en.wikipedia.org/wiki/Artificial_pacemaker
http://www.medicinenet.com/pacemaker/article.htm