The evolution of human skin color answers. Evolution of Skin Color Flashcards 2022-10-06
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The evolution of human skin color is a fascinating topic that has long been the subject of scientific study and debate. The variation in skin color seen among humans is the result of adaptations that occurred over time as our ancestors migrated to different parts of the world and faced different environmental pressures.
One of the primary factors that has influenced the evolution of skin color is the amount of sunlight that an individual is exposed to. In regions with high levels of sunlight, such as equatorial Africa, the skin of early humans evolved to be darker in order to protect against the harmful effects of ultraviolet (UV) radiation. Darker skin contains higher levels of the pigment melanin, which absorbs UV radiation and helps to prevent DNA damage and skin cancer.
As humans migrated to regions with lower levels of sunlight, such as Europe and Asia, the selection pressure for dark skin decreased. In these environments, lighter skin became advantageous because it was able to produce more vitamin D when exposed to sunlight. Vitamin D is essential for the absorption of calcium, which is necessary for strong bones. Lighter skin also reflects more sunlight, which can help to keep the body cool in hot environments.
In addition to the adaptive value of lighter skin, there is also evidence that the evolution of skin color may have been influenced by sexual selection. In some cultures, lighter skin is considered more attractive, and individuals with lighter skin may have had an advantage in attracting mates.
Overall, the evolution of human skin color is a complex process that has been shaped by a variety of factors, including the need to protect against UV radiation, the production of vitamin D, and sexual selection. Understanding the evolution of skin color can help us to better appreciate the diversity of human cultures and the ways in which our ancestors adapted to different environments.
Skin Color and Natural Selection
Otherwise, the implication would be that some humans are more highly evolved than others! After humans were dispersed from the Tower of Babel, the emigrating populations would have encountered vastly different environments. Dark skin became a disadvantage. Answers in Genesis is not responsible for content on the websites to which we refer. The influence of genes, the environment, and social factors on the evolution of skin color diversity in India. The images in Figure 2 show that the size and number of melanosomes, and the amount of melanin, are different in people with different skin colors. The A allele evolved and spread among European populations, but not in Asian populations, so some other genetic pathway for forming light skin must have evolved.
Some headed closer to the equator, some stayed in the mid-latitudes, and others headed farther north. Scientists could measure the average skin color of people at different locations throughout the world and compare Skin reflectance increases as you move north and south from the equator. The case has been used in a first-year introductory biology course for non-majors. . Jablonski explains that melanin, located in the top layer of human skin, absorbs UV radiation, protecting cells from the damaging effects of UV. These are a few questions that form the basis for what Penn State anthropologist Nina Jablonski calls an explanatory framework of the evolution of skin pigmentation in modern human beings. Running time: 18:58 min.
Of course, creationists agree that differences in human skin color can be traced back to the process of natural selection. Sample answer: Not really; although people who are homozygous for the G allele have the highest amount of melanin and the darkest skin color and people who are homozygous for the A allele have the lowest amount of melanin and the lightest skin color, there is a large amount of overlap among the groups. Photosynthesis of vitamin D3 in the skin depends upon the solar zenith angle, which changes with period, latitude, as well as time of day, as well as is more regulated by the quantity of pigment and density of the skin Mawer and Davies, 2001; Lips, 2006. Conversely, those traveling toward the poles benefited from lighter skin, and those in the population with darker skin failed to produce enough vitamin D. And this evolution has implications for our health.
Produced by: HHMI BioInteractive. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources. Some lessons may be too challenging for a regular high school biology course. Four weeks of vitamin D supplementation improves nitric oxide-mediated microvascular function in college-aged African Americans. It all began in the early 1990s when Jablonski began exploring gaps in the literature about the evolution of human skin and skin color. However, as our forebears began to migrate, wandering far from the equatorial sun, not enough UV could make its way through the protective melanin. Find your approximate location on the map.
A certain amount is required for vitamin D production, but too much can destroy folate. Human populations living in different parts of the world have different sets of evolutionary adaptations. After ten years of digging, the two had arrived at what amounts to the first comprehensive theory of human skin color. Focus on European and Asian populations. The cladogram in Figure 6 shows that zebrafish and humans share a common ancestry.
the evolution of human skin color case study answers
The answer has to do with the angle of Earth relative to the sun. Most states in the U. Genetics determines the type of melanin i. The answer, Jablonski reasoned, involves another key vitamin—and the history of human migration. In the process, some populations gained increased exposure to ultraviolet rays from the sun, while others those moving north had decreasing exposure to UV light. The evolution of human skin and skin color.
2022 UPDATED!!! THE EVOLUTION OF HUMAN SKIN COLOR BY ANNIE ANSWER KEY
Why and how did lightly pigmented skin come about? Darker skin colors evolved because they provided increased fitness in early human populations living in equatorial Africa. Journal of the Royal College of Physicians of Edinburgh, 42, 58-63. Thus the evolution of variation in human skin color is due to the balance between needing protection from UV to maintain circulating folate levels and needing some UV to prevent vitamin D deficiency. It has nothing to do with molecules-to-man evolution, because no new information originates in the human genome. Students take on the role of the scientist in exploring their own genomes and heritage. And thanks to all of our readers who have submitted great news tips to us. American Journal of Physical Anthropology, 168 S67 , 4-26.
Our research on the evolution of human skin and skin color has demonstrated that skin color is the product of natural selection acting to regulate levels of melanin pigment in the skin relative to levels of ultraviolet radiation UVR in the environment. American Journal of Physiology-Heart and Circulatory Physiology, 319 4 , H906-H914. Skin color was darkest where surface UV was strongest, the overlay clearly showed, and lightest where surface UV was weak. When they compared these data with geographical records of skin color variation, they found an overwhelming degree of correlation. Melanin is a natural sunscreen that prevents the breakdown of certain essential biomolecules in particular, the B vitamin folate, and DNA , while permitting enough UVR to enter the skin to promote the production of essential vitamin D. A change in a DNA sequence will change the mRNA that gets formed, which could result in a code for a different amino acid and ultimately a different protein. To become a paid subscriber, purchase a subscription Teaching notes are intended to help teachers select and adopt a case.
American Journal of Human Biology, 30 5 , e23170. Evidence from different disciplines can inform what makes a human trait beneficial or harmful in a particular environment. Scientific knowledge is based on empirical evidence. This details aids us recognize the basis of the biogeographic circulation of skin shades. Vitamin D3 is made in the skin when UVR permeates the skin and also is absorbed by 7-dehydrocholesterol 7-DHC in the epidermis and dermis to create previtamin D3.
Stellenbosch, South Africa: AFRICAN SUN MeDIA. These traits are known as adaptations. The more challenging lessons could be particularly useful in an AP biology course. Proceedings of the National Academy of Sciences, 112 26 , 8052-8057. American Journal of Physical Anthropology, 175 2 , 437-447.
