Thursday, April 15, 2010
The Present Day
Most of the prompts talked about earlier were either about the past or the future but "what about now?" Coyne said, "Although selection doesn't seem to have produced major differences between races, it has produced some intriguing differences between populations [<---italicized] within ancient groups. Since these populations are quite young, it is clear evidence that selection has acted in humans within recent times" (216-217). Coyne provided an example of how people begin to lose the ability to digest lactose after weaning becoming lactose intolerant. Provide another example to show how natural selection has occured in humans within recent times. Also, What changes in future populations would today's society cause?
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I don't know how recent you are looking for, but, if we are discussing "recent" in evolution time, there have been a record of over 700 genetic variations that developed in the recent 10,000 years. However, even within the human population, variation is occurring causing a diverse group of humans.
ReplyDeleteHowever, one of the phenotypes that humans have expressed differently than other humans is skin pigmentation. Within the human population, the environmental pressures altered the human skin color depending on what type of environment and weather was more prominent in the biome.
For example, the human population that has lived in a sunnier climate for a long time will have a darker skin. This is not solely because the population got "tan" as some evolutionary ignorant people might say, but the fact that this helps the skin from becoming mutated, also known as melanoma (a type of skin cancer) by the dangerous light waves that the sun emits still even through the atmosphere.
Those that live in cooler and not as sunny climates will be found to find lighter skin. An ignorant person may state that this is simply because the person was not in the sun long enough to get "tan", but over thousands of years, the skin becomes naturally lighter, because there is no need for darker skin since the chances of developing melanoma are significantly lower. Also, another advantage for lighter skin is the increased production of vitamin D, which is essential for calcium regulation and kidney functions. So, regardless of whether one is darker skinned or lighter skinned, they both have their own advantages.
This idea is related to the theme interdependence to nature because the natural pressures of sunlight gives way to natural selection of the optimal human for the certain climate and biome. Darker skinned people will be seen as "fitter" in the sunnier climate regions, while the lighter skinned people will have a "fitter" advantage in not as sunny climate regions.
Sources:
http://www.eurekalert.org/pub_releases/2006-03/plos-mth030206.php
http://whyevolutionistrue.wordpress.com/2009/04/06/recent-selection-in-human-populations/
A 'recent' adaptation in the human race that could have occured could be based on the vertical location at which a population lives. Higher altitudes call for larger or more effective lungs in order to be able to perform cellular respiration with the low amount of oxygen that is available in higher altitudes. In order to survive at higher altitudes, the populations of people that lived on mountains would have had to develop a way to get the same amount of oxygen in order to survive or develop a way to survive with less oxygen. For example, Tibetans developed a trait of expanded blood vessels that allowed for more blood to flow, and therefore allow oxygen to be transported more efficiently and quickly throughout the body. Andeans, on the other hand, have a higher amount of hemoglobin in their blood. Having a large amount of hemoglobin in the blood increases the amount of oxygen that can be transported throughout the body.
ReplyDeleteThis topic could relate to the theme of evolution. Humans in certain areas or environments had to adapt and evolve to survive in the different conditions and challenges that were posed in the different climates or altitudes. This topic could also relate to the theme of structure and function, because the structure of the bodies of the people in higher altitudes had to change in order to function properly and allow the people to survive.
Future adaptations or changes that could occur could possibly include the deterioration or lessening of bone strength and the massive increase of fat. If you have seen the movie Wall-E, that is what happened to the population in the future in the world. Since our technology is expanding so rapidly and making everything so much more convenient for us humans, it could potentially make everyone lazy. Going from running to horsebackriding to driving to self driving cars to hover chairs that lift us to wherever we need to go.
http://www.morning-earth.org/graphic-E/Transf-Adapt.htm
http://news.nationalgeographic.com/news/2004/02/0224_040225_evolution_2.html