The Biology of Skin Color. Summarize the role of solar radiation in variations of human skin tone.
People far from the equator.
Dark skin is found in populations near the equator. why?. Human genetic variation across populations is relatively low for a mammal. Before the mass global migrations of people during the last 500 years dark skin color was mostly concentrated in the southern hemisphere near the equator and light color progressively increased f a rther away as illustrated in the map below. Results from the lack of lactase.
It seems that this group intermingled with a group of farmers from the Near East who had genes for white skin. Populations closer to the equator tend to have dark skin for protection against UV since overexposure to UV may decrease folic acid levels 8 9 and cause skin cancer 10 11 12 13. This triggers the DNA to produce melanin a dark skin pigment that helps block UV rays.
Most investigators believe that black pigmentation was an essential adaption to protect naked pale skin against solar ultraviolet radiation which is high all year round near the equator. B It Protects From Gverexposure To Ultraviolet Radiation. Lower frequencies of lactose intolerance tend to be found in these populations.
Ancient populations in Sweden around the same time the researchers found already had genes for pale skin and blue eyes. Dark skinned individuals are at _____ near equator because their skin color _____. Askin color BABO blood type Chair color Dnone of these ANS.
It Protects From The Damaging Effects Of UV Radiation On Fol E It Increases The Skins Exposure To Ultraviolet Radiation. Pigmentation skin color in humans has evolved under selection pressure from the duration and intensity of sunlight. Therefore individuals that live nearer the equator have darker skin colors all the time while individuals living the higher latitudes on Earth may only produce.
Ancestral populations near the equator were selected for dark skin while those living in higher northern latitudes were selected for lighter skin. In fact the majority of dark pigmented people lived within 20 º of the equator. The only reason why no northern populations have very dark skin is mostly just a coincidence.
At the poles the skin of indigenous people is almost always lighter. Which is when the trait is partially dominant and is expressed intermediately. That suggests that variation in human skin melanin production arose as different populations adapted biologically to different solar conditions around the world.
Measures of skin reflectance a way to quantify skin color by measuring the amount of light it reflects in people around the world support this idea. People from tropical regions of the world at or near the equator generally have darker skin than people who live in temperate regions farther from the equator because variation in human skin color is closely related to geographic variation in solar radiation. Black and White.
They found that in Southern Europe Europeans had dark skin. The lighter skin in populations at higher latitudes is underlying selection to maintain vitamin D photosynthesis which is a UV-dependent process 14 15. Is dark like it is near the equator or at high altitude.
Theres a convincing explanation for why human skin tone varies as a global gradient with the darkest populations around the equator and the lightest ones near the poles. Skin color is a incomplete dominant trait. If 1 a population in Siberia has the gene for dark skin one in every 100 people would be born with a tan looking medium skin tone.
Dark skin is a type of human skin color that are rich in melanin pigments especially eumelanin. The darker skin of peoples who lived closer to the equator was important in preventing folate deficiency. Near the equator a light skin is damaged by the sunlight while a darker skin with more pigmentation can withstand this sunlight and thus in these latitudes having a dark skin is an advantage.
Dark Skin Is Found In Populations Near The Equator. Prevents photo destruction of folate. Dark skin is found in populations near the equator.
People with very dark skin are often referred to as black people although this usage can be ambiguous in some countries where it is also used to specifically refer to different ethnic groups or populationsThe evolution of dark skin is believed to have begun around 12 million years ago in. In your explanation include information as to why reduced pigmentation leading to lighter skin colors is advantageous for populations indigenous to northern latitudes. Areas closer to the equator receive almost direct UV rays from the Sun all year around.
Rely heavily on dairy farming. A It Protects From Frostbite. It Helps Prevent Rickets D.
Put simply dark complexion is advantageous in sunnier places whereas fair skin fairs better in regions with less sun. The need for vitamin D during pregnancy may explain why women around the globe tend to have lighter skin than men.