Stronger, Faster, Better, we have the adaptability
Stronger, Faster, Better, we have the adaptability
Moments before its life is abruptly ended, a particularly sneaky and cleaver mosquito pushes its needle into the back of a man who lives in Africa. Unfortunately for our African friend, the mosquito carried with it the disease known as malaria. More unfortunately was the fact that the malaria had already been in contact the African’s blood, which normally would most likely result in a nasty case of malaria. However, all his life this African carried with him a genetic disorder known as Sickle Cell Anemia. While this disorder can be life threatening when ill treated, it makes our African friend immune to malaria. After years and years of malaria outbreaks, many people in Africa have adapted to their environment. This is human adaptation at its best, the human observes a problem in its life and slowly it changes itself to live in harmony. The Human body is an amazing organism that is capable of adapting to nearly any environment or situation. It is this ability to change with the times that have lead us down the evolutionary path to dominance. Humans are at the top of the food chain, they have overcome against all odds and evolved from single celled organisms into the complex being that we are today.
Chevalier de Lamarck was a famous scientist throughout the eighteenth and seventeenth centuries. He was a professor of zoology at the museum of Natural History of Paris. While working at the museum he developed his own theory of evolution that made him one of the pioneers of evolutionary theory. “He conceived of evolution as the result of the adaptation of
organisms to the environment and that this adaptation was transmitted from parent to offspring” (Comas, 55). Lamarck believes that something changes in the environment and individually organisms change to best fit their needs. After a series of similar adaptations the species will change and possess these new traits. Also included in his evolutionary theory are four important principles: Life tends to increase the size of an organism, not just its overall size, but every part. Each organ is there for a specific need or want that was once in the environment. Organs are like muscles, the more they are used and worked out the stronger and more developed they become; conversely, the less they are needed the smaller and weaker they become. Finally, all of an organism’s traits are acquired by its parents through heredity. “Habit constitutes a second nature and produces two types of modifications, one by means of progression or development and the other by means of regression or degeneration” (Comas, 57). Lamarck’s model for evolution can be shown to apply for humans very easily. For example, a tree dwelling ancestor of the modern human would have opposable thumbs on both his hands and his feet, for climbing. After several generations of just using feet for walking, the opposable thumb on the feet would not be used and slowly shrink until it becomes just another digit. Lamarck has a very logical theory that is simple and easy to follow. Nature presents a challenge and then individuals try and adapt to overcome and live the rest of their lives. The best thing about Lamarck’s theory is how it makes adaptation and evolution into a deliberate process. Its not dumb luck doing the evolving, it is the organism making a conscious effort to survive. Lamarck gives more credit to the organism than to Mother Nature, instead of nature selecting who will survive and who will not, the organism must learn to fight for its right to live. It must become stronger and more capable in all situations. This theory is much more inspiring and makes the organism out to be a hero.
Another pioneer in modern evolutionary theory is Charles Darwin. Darwin’s major contribution to the subject is the theory of natural selection. As the environment changes, the
organisms it affects either change with it in the form of mutations, or they die. The ones that mutate in the best way possible are the ones that survive to pass on their genes. This way these life saving genes are present in all offspring. “All living beings struggle for existence. When the food supply is insufficient the individuals of a certain species who, through chance, have acquired specific advantageous traits, are better equipped for this vital struggle for existence “(Comas, 66). Mutations in nature due to environmental changes are not always for the best, they only solve the problem at hand. For example, if food quantities slowly diminish over time, then most likely the size of the organism will decrease. However if this organism is much smaller then it could be more vulnerable to predators. Darwin is one of the most credited of the evolutionary theorists. His theory of natural selection gives the majority of the credit to accidental mutations that just happen to work out. Darwin’s evolutionary theory is like putting a completely disassembled Tissot wristwatch into a bag, and then one shakes the bag until the watch is reassembled.
Adaptation is “the ability of an organism to adjust to a changing environment such that survival and reproduction are enhanced” (Boaz, 122). The human body simply changes its chemical or physical composition so that it is most benefited in its current situation. Adaptation is the basis for evolution; they are very similar and intertwined. Adaptation occurs when the human body undergoes stress. Stress is any change in the environment that makes it difficult for the human body to strive. “Stress involves some environmental stimulus that produces a reaction in a living organism that may be either favorable or unfavorable to the organism” (Boaz, 126). There are many stresses that can occur, something as simple as the distance to the nearest water supply, or something as complex as the change in acidity in that same water supply. Either way, the human body changes or mutates so that it can still survive.
When dealing with human adaptation there is an important hierarchy of permanence. The first step an organism goes through is Acclimatization. This is the change occurring in an organism to reduce the strain of a certain factor, all during the organism’s lifetime. This stage is also referred to as developmental adaptation. The next step is acclimation, which is the biological change an organism and its offspring go through during one experimentally induced stress. Finally is habituation, which is a gradual adaptation to some environmental or ecological threat. It is a permanent change that first shows up in the offspring of any creature, and deals with that one stress so that the organism can live its life in peace (Frisancho, 4)
Heat stress is among the most common types of stresses, humans experience heat stress typically in the summer time or in the temperate zones of the world. The first human response to heat is increased blood flow, a loss of insulation and Vasodilation. The increased blood flow in the human body acts like a radiator of a car. The volume of blood circulating increases greatly, allowing the blood to release some heat at the same time. People turn red in heat because the blood is trying to get as close to the surface as possible so that it can cool off (Frisancho, 25). The next step when things heat up is the evaporation of sweat on the body. When we first start to sweat, it cools us off, but not nearly as much as when it evaporates. When the liquid evaporates then the heat energy is released and it cools us down. After generations and generations of being exposed to extreme heat, the human body will stretch itself out. Having longer limbs makes the blood travel farther to cool off, so in the heat, it’s best to be tall. (Frisancho, 31).
Adapting to cold is a much more complex and difficult function than adapting to heat. The first biological response to cold is shivering. When it is cold outside and one just needs that one last boost of warmth, and then shivering will warm someone up just enough to survive a little bit longer (Frisancho, 53). Vasoconstriction is also a primary response to cold. The blood
vessels slow down greatly in an attempt to conserve heat. As a result the skin temperature decreases greatly, and eventually frostbite will set in. Frostbite occurs when the blood flow to a particular area of the skin depletes greatly. The blood is too cold and too slow to keep the skin warm, and so feeling is lost and the skin turns white. The longer that the human body is in the cold, the more risky it is. After some time, the body starts to cut off blood flow to the limbs, in an effort to conserve heat. The body slowly shuts down system after system starting with the least important to survive. After even more time the body dies and freezes wherever it is at the time. People who survive a long time in a very cold environment are often much smaller than people in a tropical or temperate climate. They have shorter and thicker limbs so that they can have a much smaller blood flow, and they often have more fat to be used as insulation (Frisancho, 81).
When a person spends much of their time at a high altitude, they are greatly affected. Many athletes go to places like Denver, Colorado or any other place at a high elevation to train. Up at a high altitude the percent of oxygen is much smaller, which means with each breath we take in there is less oxygen then we are used to. To counteract this affect the body increases lung volume, and engages in respiratory alkalosis. Respiratory alkalosis is when the blood becomes alkaline because of the increased amount of carbon dioxide taken in. This extra carbon dioxide is taken in because of increased ventilation; people take more breaths to get more oxygen. Also, the volume of the blood increases very much. Specifically, the production of hemoglobin and plasma increase greatly (Frisancho, 110). Being at a high altitude causes a temporary disorder called hypoxia. Hypoxia is simply the increase in breathing and hemoglobin to make up for the lack of oxygen in the atmosphere. Some people are nearly immune to the affects of changing from one altitude to another; it depends primarily on age and physical fitness.
The human body is an amazing thing that has come a long way from its beginning. All the topics discussed so far are very relevant because it is just now that the human race is beginning to see its true potential. The human body hasn’t changed drastically in a long time and who knows what road or path we are headed on. With the increased use of technology in the world, adaptability is becoming less of a necessity. Why suffer through the cold winter when you can just turn up the heat? The human race is a spectacular smorgasbord of different people and ideas that have always found a way to be on top. Hopefully we will stay that way and spread our knowledge to all corners of the universe.
Baker, Paul T and Weiner, J.S. The Biology of Human Adaptability. Oxford, England: Clarendon Press, 1966
Boaz, Noel T, and Wolfe, Linda D. Biological Anthropologt: The state of the science. Bend, Oregon: International Institute for Human evolutionary Research, 1995
Comas, Juan. Manual of Physical Anthropology. Springfield, Illinois: Charles C Thomas, 1960
Frisancho, Roberto A. Human Adaptation: a functional Interpretation. Rexdale, Canada: C. V. Mosby Company, 1981
Hettema, P.J. Personality and Environment: Assessment of human adaptation. New York: John Wiley & Sons, 1989
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