2006-06-23 03:38:35 · 16 answers · asked by sarthak h 1 in Science & Mathematics ➔ Biology
different races
2006-06-23 03:40:17 · answer #1 · answered by Backwoods Barbie 7 · 0⤊ 0⤋
Different environments different adaptations.
Skin color is regulated by only six genes, so natural selection can rapidly make changes should the need arise.
The amount of UV light exposure related skin cancer factors in as an agent of natural selection. By exposure I don't just mean what comes down from the sky, but how much people actually get exposed to as related to their lifestyle. More UV exposure = darker skin.
The diet's content of either vitamin D or its precursors which require some UV exposure to be turned into vitamin D. The vitamin deficiency caused by a lack of vitamin D stunts bone growth and causes a jump in the number of deaths during childbirth for both mother and offspring. Less vitamin D and/or less UV exposure to process precursors = lighter skin.
Women darken slightly after menopause, which has caused a slight but measurable preference among men for women who are lighter than the populations average (assuming unmixed populace). This qualifies as 'sexual selection', but it is one factor among many others so is easily overwhelmed by environmental needs for better UV protection.
2006-06-23 04:16:38 · answer #2 · answered by corvis_9 5 · 0⤊ 0⤋
Many different theories. People think that white people are actually a mutation of a gene.
But the one that holds the most water to me is places of different exposures to the sun. Like black skin means their decendents were somewhere with a lot of sun.
2006-06-23 03:43:28 · answer #3 · answered by Sam L 2 · 0⤊ 0⤋
Well here's my reasoning.
Closer to the equator is hot. The skin nearby to Africa is darker. The pigments are dark, and doe snot get easily sunburned. There eyes are darker which are less sensitive to sun. People who are around the equator usually have dark complexions, eyes, and hair.
Now look at Europe. People ther have fair complexions. Blond hair, blue eyes. Light Skin. The pigments are made lighter because of their surroundings. Blue eyes are more sensitive to light. In Europe, they do not have as strong sunlight and heat as in Africa. Their skin also sunburns easily because the sun is not as strong. The reasons of race all make sense.
Hope I helped!
2006-06-23 03:47:20 · answer #4 · answered by fortunamajor 4 · 0⤊ 0⤋
Melanin, or skin pigment is found in larger quantities in people near the equator to protect them from more sunlight. Conversely, it's found in smaller quantities in people closer to the poles to allow them to take advantage of much less sunlight.
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Uhm, I'm seeing a lot of guess work and personal theories in here-- if you don't know already-- this is not a scientific mystery folks-- it hard fact.
2006-06-23 03:43:54 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Combination of environmental factors and melanin content already present in the skin
2006-06-23 05:01:13 · answer #6 · answered by icehoundxx 6 · 0⤊ 0⤋
Because the climate at different places are also different.
2006-06-23 03:43:55 · answer #7 · answered by Chie 5 · 0⤊ 0⤋
The color of your skin is depicted by a pigment called melanin. the same pigment determines the color of your iris. But sorry, I dunno how it differs in different places. May be due to the temperature or the food habits!
2006-06-23 21:49:59 · answer #8 · answered by Shruthi 2 · 0⤊ 0⤋
it depends on the melanin content of the body and factors like the environment and the heat or rather temperature of the particular area
2006-06-23 03:51:01 · answer #9 · answered by aru 2 · 0⤊ 0⤋
Genetics and the different climates.
2006-06-23 03:42:44 · answer #10 · answered by Anonymous · 0⤊ 0⤋
Why do you come on here with this different question
2006-06-23 03:41:48 · answer #11 · answered by J.B. Goode 3 · 0⤊ 0⤋