Examples of Human Ability to Adapt to Changes
Throughout the centuries human beings like many other of the species on earth have learned to adapt to changes in the environment. The term adaptation is being referred to the different ways a population can easily adapt to the environment and successfully survive and reproduce. Some of these changes would include diet, biodiversity, and climate changes.
Multiple researches done in the area of anthropology have brought up some etiologies to explain all of these environmental changes and how humans have been able to successfully adapt. Some of the most common evolutionary adaptations that were discussed in class and I will be discussing in this paper are genetic adaptations such as the example of genetic mutation of sickle cell, second acclimatization and larger lung capacity, third example of adaptation is skin color and UV resistance, fourth we have atmospheric temperature impact on body size and shape, and lastly I will be discussion about diet adaptation through digestive enzymes.
I will start off by introducing Allen’s and Bergmann’s rule which correlates different climate temperatures to body form and shape. As the literature explains, Allen’s rule states that body size is leaner in places of warmer climates and more rounded and compacted in colder climates. Bergmann’s Rule states that people from higher altitudes or colder climate have a body size larger and thicker vs. populations in warmer climates. These attributes are basically explaining thermal resistance. Shorter and rounded bodies are able to preserve heat in environments of colder climate. Longer and leaner bodies are able to cool off quicker in places of warmer temperatures, they also have more surface area to release sweat.
The next evolutionary adaptation I will be discussing is also an example of acclimatization, which is basically the result of adjusting to a new climate. Research has shown that those who have grown up at high altitudes have a larger lung capacity vs. people who have moved to high altitudes later in life. This is because in higher altitudes less oxygen is available for a person to breathe, by developing larger lung capacity a person is able to hold greater total amount of air and therefore larger amounts of oxygen is available to adequately supply the body tissues and not cause body damage. People who move to higher altitudes in there later years, meaning as adults are able to slowly adapt but with a higher risk of future medical complications.
Another great example of human adaptation to changes in the environment is skin color and UV resistance. Different skin tones among humans are probably the most common genetic variation that results from evolution. Research has found that people from colder climates such as Alaska have less sun exposure to those who live in warmer climates. By having less sun, they have less exposure to UV radiation making them more vulnerable to skin damage and less production of Vit. D, which is an essential vitamin for human health. Vitamin D aids with calcium absorption for maintaining strong bones, and it is also critical for hormonal balance. As literature explains populations from colder climates have created ways that allow them to adapt to their environment.
For instance farming mushroom, mushrooms can easily absorb Vit D, by including this in their diet people from colder climates are able to supply their body with this essential vitamin all year round. Through generations populations in warmer climates have developed darker skin tones, which makes them more resistant to UV radiation and therefore less sensitive to skin damage. The different skins pigmentations can be consider a complex evolutionary trait that has resulted from their phenotype, an interaction of the genetic makeup from ancestors and exposure to a specific environment.
Another great example of human adaptation is the Genetic mutation of sickle cell and malaria resistance. Research findings have shown that natural selection has favor human adaptation to some infectious diseases such as malaria. Sickle cell is a genetic disorder that causes red blood cells to become deformed into a crescent or “C” like looking shape and burst easily. People with this condition are more likely to suffer from anemia, which is basically a deficiency of red blood cells (hemoglobin) in our blood since the cells are easily broken as the result of this disease. In tropical areas, incidence of malaria fever are higher and easily transmitted by mosquitos affecting red blood cells. As literature explains tropical regions with higher prevalence of malaria have also been found to have an increase amount of people with sickle cell disease. Sickle cell carriers have a higher resistance to malaria fever since they are constantly restoring their red blood cells also known as hemoglobin.
The last evolutionary human adaptation that I will be discussing in this paper is diet. From our ancestors to this modern day our diet has significantly changed, and not necessary for the best. Looking at our human history and ancestry we went from being hunter-gatherers to modern industrialization and ready prepare foods. With in these evolutionary traits we can see some physical and genetic changes.
We can see the physical adaptations by looking back at our hominine lineage and how our physical morphology has changed and adapted. Literature explains that by comparing modern humans to our ancestry we have developed smaller guts, larger brains and molar adaptations have also been seen. All this physical changes started to be more pronounced with the use of fire and cooking our foods. Cooking foods, especially meats minimizes energy expenditure in digestion and increases our intake on high quality/calorie dense foods of which animal meats are considered, therefore we have more energy available for brain development and usage leading to having larger size brains. Since food becomes more easily digestible our guts become smaller, which also allow us to have greater physical fitness and capability for hunting and gathering with less body mass to carry. Our jaws and molar size also become smaller as our food size and texture changed.
Genetic adaptation through our evolutionary changes in our diet have also been seen. Two great examples of this are the role of the digestive enzymes lactase and amylase. Lactase is the enzyme that helps with the breakdown of lactose, which is the natural sugar found in milk. This allows for the brake down of lactase into glucose and galactose units making the protein in milk to be digestible and available to be utilize by your body, for instance glucose for body energy and the protein for muscle integrity and build up.
Through out the globe literature explains that not all humans have developed the genetic ability to brake down lactose. Natural selection has favor people from agricultural regions where grazing and raising cattle is a main part in their environment, therefor they have developed and through the years naturally count with this important enzyme as part of there genetic makeup. To modern day we see people who suffer from lactose intolerance, which is mainly seen in populations that originated in South Asia and parts of Africa.
The most common physical symptom a person who is intolerance to lactose can experience by ingesting regular dairy products is gastrointestinal stress, causing stomach pain, excessive gasses and diarrhea. Recent studies have also found that the intolerance can vary and not all dairy products are need to be avoided. Some people have shown to be low lactose, which means that they avoid caw’s milk but are able to tolerate yogurt and cheese with no GI discomfort. Something else to consider is that often times old cheeses and some yogurts not longer have this enzyme or have it all ready broken down which occurs during the processing on the food item.
Salivary Amylase is another crucial digestive enzyme, which plays an important role in digestion. When we place food in our mouth, especially starchy food, amylase activates and is released through our saliva. Amylase enzymes in saliva are where digestion of food starts, this enzyme as explained by literature aids with the breakdown of complex sugars such as starch as previously mentioned. The starch gets broken down into simple sugars that are able to than be carried on by other enzyme and move down our digestive system heading towards the small intestine where digestion continues.
From Hunter-gatherers who survived on many root vegetables and tubers in their diet to Americans, Europeans and Japanese who included high amounts of starches in their diet with foods such as rice. These cultures are among the ones that have been found to have diets heavier in starch and therefore also higher amylase genes in individual in the population. This has not only allowed them to have higher quality foods and higher quality of energy supply but also more resistance to physical GI stress such as diarrhea.
In conclusion all the human adaptations physical and genetic discussed above are only a few of the many ways humans have adapted physically and genetically which has led to changing the course of our genetic pull. We are in a way able to see this through our global racial diversity. Through these examples we can see how we have slowly been evolving out of our hominines ancestry and become the moderns society that we now see.
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