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Your Family May Once Have Been A Different Color Listen Now [7 min 19 sec] add to playlist
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Courtesy George Chaplin Click to see a global skin color map, adapted from 2004 data.
Morning Edition, February 2, 2009 · To begin, please point your elbow to the ceiling.
Then imagine yourself naked.
Then look at the patch of skin on the inside of your upper arm, the part of you that almost never sees the sun. Whatever color you see there is what experts call your basic skin color, according to professor Nina Jablonski, head of the Penn State Department of Anthropology.
And that color, the one you have now, says Jablonski, is very probably not the color your ancient ancestors had — even if you think your family has been the same color for a long, long time.
A Different Place, Different Color
Skin has changed color in human lineages much faster than scientists had previously supposed, even without intermarriage, Jablonski says. Recent developments in comparative genomics allow scientists to sample the DNA in modern humans.
By creating genetic "clocks," scientists can make fairly careful guesses about when particular groups became the color they are today. And with the help of paleontologists and anthropologists, scientists can go further: They can wind the clock back and see what colors these populations were going back tens of thousands of years, says Jablonski. She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."
Over the last 50,000 years, populations have gone from dark pigmented to lighter skin, and people have also gone the other way, from light skin back to darker skin, she says. "People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented," Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.
"There has probably been a redarkening of several groups of humans."
Why We Change Color
The repigmenting process is increasingly well understood. "Humans started in Africa," Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.
Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don't get enough ultraviolet light, we're less likely to survive to reproductive age to produce strong-boned babies.
Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator eventually have too little UV. Hooray For Melanin
The solution is what Jablonski calls "a really cool molecule": melanin. In different concentrations, melanin makes skin lighter or darker. Kind of like a Venetian blind, it can let UV light in or keep it out.
Melanin has evolved in many different animals. Humans have had it for a long, long time and what Jablonski and others have learned is that when early humans migrated from the equator, their melanin levels changed. That doesn't mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own.
Successive mutations created successive generations of lighter and lighter people as they moved north.
"This, in short, really created the gradation of skin color that we see in modern humans today," says Jablonski. Her map of UV radiation levels on Earth closely mirrors the array of skin colors on Earth.
Skin Color Is A Fleeting Thing
The big surprise is how fast these changes can occur. "Our original estimates were that [skin color changes] occurred perhaps at a more stately pace," Jablonski says. But now they're finding that a population can be one color (light or dark) and 100 generations later — with no intermarriage — be a very different color.
Figuring 25 years per generation (which is generous, since early humans walked naked through the world — clothes slow down the rate), that's an astonishingly short interval.
It's "a blink of an eye," she says.
Jablonski is the author of Skin: A Natural History, published in 2006. These newer findings are mentioned, in a preliminary way, in that book.
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Looking at the map and seeing how black skin radiates from Africa, can we say; All Blackness comes from Africa?
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Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
She's stealing and repackaging my stuff! What she is "implying" is that UV exposure led to Albinism, which in turn created havoc on European immunization and productive capabilities.
What she left out is that the lack of melanin in those past generations is what allows UV to cause damage to DNA since Albinos lack the basic protective coating of melanin nature provided to protect DNA from exposure and damage. 50-100 generations ago in Jablonski's family were very likely strong OCA1 Albinos. Over the generations, she has decreased these symptoms to sub-clinical OCA2 levels.
Look how much sun screen Jablonski squirts on her face before getting in the sun. Looks like she uses half a bottle and she has very little skin melanin.
quote: "People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented," Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.
Is absolute nonsense. The people of Sri Lanka are part of the aboriginal populations that migrated out of Africa and have been black SINCE that migration. But of course, whites just cannot stand to admit that they descend from blacks so they have to make up nonsense to make everything seem equal or that whites are as ancient as blacks when they aren't. South Asia is one of the oldest places first colonized by early humans, including Sri Lanka and therefore it is HIGHLY doubtful that any ancient Sri Lankan turned black from being white in the North because the first Sri Lankans did NOT come from the North. The earliest remains from Sri Lanka are of Australoid aboriginal type people that were the ancestors of those who moved north or at least their close cousins as the earliest populations in the North Also had the same features. If anything, the modern Sri Lankans are a combination of the aboriginal dark inhabitants with a range of populations some of whom were lighter skinned people from the North. They are not the same people as the aboriginal Sri Lankans of long ago. In fact, the aborigines of Sri Lanka are almost extinct according to some sources. Developing dark skin due to intermarriage is not the same as developing dark skin as a process of evolution. And it is certainly unlikely that the aboriginal black populations of South India and Sri Lanka ever disappeared or got there AFTER some light skinned migrants from the North.
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^^^Another White persons theory on why White people exist. And like all the rest, they are quite plausible, if you don't think too deeply. The parts about melanin and the bodies metabolic requirements are true, but however, that convenient little scenario does NOT account for the obvious differences in phenotype.
In very general terms; Negroid or Black is characterized by tightly curled hair to straight hair, broad and flat to small and narrow noses, long heads and broad heads, very full to thin lips, dark hair and eyes - with rare exceptions, some with eye folds, and ALWAYS dark skin.
On the other end, Mongols are characterized by broad heads and very straight hair, dark hair and eyes, White skin - and some with eye folds.
And the "Typical White" person is of the "Nordic" type - Germanic peoples of northern Europe and especially of Scandinavia" or "of or relating to a group or physical type of the Caucasian race characterized by tall stature, long head, White skin and hair, and blue eyes".
From phenotypes we can easily discern the originating Black race, because it encompasses the traits of all the others except for skin color.
The Mongol race shows affinity with the Black race in that all of its types such as eye folds, straight hair, broad head, and nose types, can be found in Black populations. The exceptions being very full lips and White skin. Thus the scenario put forth by Nina Jablonski could very well work for MONGOLS!
Whites however are another story; the exaggerated phenotype differences in the White race cannot be explained away by geographical displacement. If that were true, then Mongols who experienced the same displacement, would display the same exaggeration, they do not.
In addition, it has been genetically determined that the White race started with as little as seven breeding pairs. This of course explains the tight phenotype range. But it also indicates a separate, unique and unusual circumstance for these founding breeders. To date, only the theory of an Albino colony explains the narrow range of physical attributes and phenotype for White people.
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quote:Originally posted by meninarmer: Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
She's stealing and repackaging my stuff! What she is "implying" is that UV exposure led to Albinism, which in turn created havoc on European immunization and productive capabilities.
What she left out is that the lack of melanin in those past generations is what allows UV to cause damage to DNA since Albinos lack the basic protective coating of melanin nature provided to protect DNA from exposure and damage. 50-100 generations ago in Jablonski's family were very likely strong OCA1 Albinos. Over the generations, she has decreased these symptoms to sub-clinical OCA2 levels.
Look how much sun screen Jablonski squirts on her face before getting in the sun. Looks like she uses half a bottle and she has very little skin melanin.
Jablonsky lives in a fantansy world. She talks about the evolution of genes and even implies that their is a specific gene for ranges in color. Then she implies in the interview that people have confirmed that there are color specific genes.
This is a lie. They have only recently confirmed that the Cro-Magnon people of Europe carried non-contemporary European genes. I have not seen any article outlining the discovery of genes for color in which they have been compared to ancient populations.
Presently, they describe ancient populations based on craniometrics--not genetics.
This whole idea of the origin of color as proposed by this researcher and others is false. Look at the map above. As we know the Eskimos are dark skinned yet they are labled in the same category as Europeans.
quote: "People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented," Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.
Is absolute nonsense. The people of Sri Lanka are part of the aboriginal populations that migrated out of Africa and have been black SINCE that migration. But of course, whites just cannot stand to admit that they descend from blacks so they have to make up nonsense to make everything seem equal or that whites are as ancient as blacks when they aren't. South Asia is one of the oldest places first colonized by early humans, including Sri Lanka and therefore it is HIGHLY doubtful that any ancient Sri Lankan turned black from being white in the North because the first Sri Lankans did NOT come from the North. The earliest remains from Sri Lanka are of Australoid aboriginal type people that were the ancestors of those who moved north or at least their close cousins as the earliest populations in the North Also had the same features. If anything, the modern Sri Lankans are a combination of the aboriginal dark inhabitants with a range of populations some of whom were lighter skinned people from the North. They are not the same people as the aboriginal Sri Lankans of long ago. In fact, the aborigines of Sri Lanka are almost extinct according to some sources. Developing dark skin due to intermarriage is not the same as developing dark skin as a process of evolution. And it is certainly unlikely that the aboriginal black populations of South India and Sri Lanka ever disappeared or got there AFTER some light skinned migrants from the North.
I agree with you. But they feel they can propagate this idea because of the limited genetic evidence that correlate some Indians with Eurasians. But this may change given the fact that some researchers believe that R1a1* is of Indian origin.
quote:
J Hum Genet. 2009;54(1):47-55. Epub 2009 Jan 9.Related Articles, Links The Indian origin of paternal haplogroup R1a1(*) substantiates the autochthonous origin of Brahmins and the caste system.
Sharma S, Rai E, Sharma P, Jena M, Singh S, Darvishi K, Bhat AK, Bhanwer AJ, Tiwari PK, Bamezai RN.
Many major rival models of the origin of the Hindu caste system co-exist despite extensive studies, each with associated genetic evidences. One of the major factors that has still kept the origin of the Indian caste system obscure is the unresolved question of the origin of Y-haplogroup R1a1(*), at times associated with a male-mediated major genetic influx from Central Asia or Eurasia, which has contributed to the higher castes in India. Y-haplogroup R1a1(*) has a widespread distribution and high frequency across Eurasia, Central Asia and the Indian subcontinent, with scanty reports of its ancestral (R(*), R1(*) and R1a(*)) and derived lineages (R1a1a, R1a1b and R1a1c). To resolve these issues, we screened 621 Y-chromosomes (of Brahmins occupying the upper-most caste position and schedule castes/tribals occupying the lower-most positions) with 55 Y-chromosomal binary markers and seven Y-microsatellite markers and compiled an extensive dataset of 2809 Y-chromosomes (681 Brahmins, and 2128 tribals and schedule castes) for conclusions. A peculiar observation of the highest frequency (up to 72.22%) of Y-haplogroup R1a1(*) in Brahmins hinted at its presence as a founder lineage for this caste group. Further, observation of R1a1(*) in different tribal population groups, existence of Y-haplogroup R1a(*) in ancestors and extended phylogenetic analyses of the pooled dataset of 530 Indians, 224 Pakistanis and 276 Central Asians and Eurasians bearing the R1a1(*) haplogroup supported the autochthonous origin of R1a1 lineage in India and a tribal link to Indian Brahmins. However, it is important to discover novel Y-chromosomal binary marker(s) for a higher resolution of R1a1(*) and confirm the present conclusions.Journal of Human Genetics (2009) 54, 47-55; doi:10.1038/jhg.2008.2; published online 9 January 2009.
quote:Originally posted by Mike111: ^^^Another White persons theory on why White people exist. And like all the rest, they are quite plausible, if you don't think too deeply. The parts about melanin and the bodies metabolic requirements are true, but however, that convenient little scenario does NOT account for the obvious differences in phenotype.
In very general terms; Negroid or Black is characterized by tightly curled hair to straight hair, broad and flat to small and narrow noses, long heads and broad heads, very full to thin lips, dark hair and eyes - with rare exceptions, some with eye folds, and ALWAYS dark skin.
On the other end, Mongols are characterized by broad heads and very straight hair, dark hair and eyes, White skin - and some with eye folds.
And the "Typical White" person is of the "Nordic" type - Germanic peoples of northern Europe and especially of Scandinavia" or "of or relating to a group or physical type of the Caucasian race characterized by tall stature, long head, White skin and hair, and blue eyes".
From phenotypes we can easily discern the originating Black race, because it encompasses the traits of all the others except for skin color.
The Mongol race shows affinity with the Black race in that all of its types such as eye folds, straight hair, broad head, and nose types, can be found in Black populations. The exceptions being very full lips and White skin. Thus the scenario put forth by Nina Jablonski could very well work for MONGOLS!
Whites however are another story; the exaggerated phenotype differences in the White race cannot be explained away by geographical displacement. If that were true, then Mongols who experienced the same displacement, would display the same exaggeration, they do not.
In addition, it has been genetically determined that the White race started with as little as seven breeding pairs. This of course explains the tight phenotype range. But it also indicates a separate, unique and unusual circumstance for these founding breeders. To date, only the theory of an Albino colony explains the narrow range of physical attributes and phenotype for White people.
The Abino theory would fit into Jablonski's theory about people of the same color living together and breeding others of the same type.
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^ The Albinism theory is the most plausible of all. Especially considering Tanzania has within it's population upwards of some 75,000 Albinos, the migrating group of Albinos theory is not only realistic, but the best theory explaining the severe lack of melanin in present day Europeans. This cannot be explained by skin Lightening due to UV absorption anymore then African Albinism can be traced to the same. Jablonski is clear that she is opposes the Albinism component but provides no adequate counter argument to dismiss it.
Jablonski's theory falls in line with the pseudo-science Rasol and KIK tried to pass off as scholarship entitled, Europeans recently turned White in Europe due to evolving Magical "White" Gene. Pure non-sense!
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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Quote: This is a lie. They have only recently confirmed that the Cro-Magnon people of Europe carried non-contemporary European genes. I have not seen any article outlining the discovery of genes for color in which they have been compared to ancient populations.
Clyde - there are many studies that allude to this, but I have not seen any that specifically discredit it. If there is a new one that does, please post it.
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^ They only "Allude" to this because as in the above referenced study, they are the same gene sequences responsible for Albinism.
In normal operation, these genes act analogous to an electrical Dimmer type switch, regulating melanin density as a Dimmer switch regulates electrical flow (light).
In Europeans, the genes are not regulated in an analog sense, but switched full off, or partially leaking (barely "On". Rasol's article (posted in Marc's, Europeans are recent to Europe thread) labeled this as, European evolution. In reality, it is scientifically described as, Albinism.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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^^^It would seem to be a simple thing to prove. I can't help but wonder how much of this ambiguity has to do with a lack of science, and how much of it has to do with embarrassment.
Anyone who has ever read the insulting and demeaning things that they have written about Black people, under the title "science" will understand their reluctance to admit that they are nothing more than "Defective" facsimiles of that very same "Negro".Posts: 22721 | Registered: Oct 2005
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^ They understand it very well. Which is the reason behind them labeling any person of color as a racist as soon as the word Albinism is mentioned.
The truth is, the world wide budget on Melanin, Albinism, and genetic research only falls second to weapons research.
Mongrels, based on their established low rate of skin cancer incident, in spite of their low melanin densities, appear to be pretty well environmentally adjusted. Europeans, on the other hand, appear to be a very unstable mutate form of human that has nowhere to hide from the earth's UV levels. They appear to be susceptible to excessive UV exposure everywhere on earth. Either their true origins are from a migrating colony of Albinos, or their ancestors were deep cave dwellers. These are the only two credible options.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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quote:Originally posted by Doug M: Deep cave dwellers! That's a good one. LOL!
What's wrong with this idea? We know that the Europeans prior to the last Ice Age used caves as santuaries and religious locales.
We also know that the last Ice Age in Europe came suddenly. Who are we to deny the possibility that when the last Ice Age came many Blacks retreated to the caves.
In the caves they lived in darkness and the melenin migrated to the hair and out of the skin cells. Then over time they became depigmented and after the Ice Age ended and Europeans left the caves they were "white" like most things that live in caves.
Note the cave fish on the left and regular fish on the right
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Clyde - I was going to lampoon you, by asking how far could they have gone on Mushrooms - now I'm not so sure.
Vitamins in Mushrooms. Mushrooms are one of the few natural sources of vitamin D, which is essential for healthy bones and teeth. One serving of 4-5 mushrooms provides 15 IU of this important nutrient, which many people do not get enough of1,2. Factors affecting your vitamin D intake include your age, skin color, where you live and whether you use sunscreen or not8,9,11. Mushrooms are also a good source of the B vitamins riboflavin (B2), niacin (B3) and pantothenic acid (B5). These vitamins help break down proteins, fats and carbohydrates so they can be used for energy1,5. Mushrooms can be an important source of B-vitamins for people who don’t eat meat. One serving of crimini mushrooms provides nearly one-quarter of the Daily Value for riboflavin, and mushrooms are one of the best plant-based sources of niacin around1,2.
* Pantothenic acid helps with the production of hormones and also plays an important role in the nervous system5. * Riboflavin helps maintain healthy red blood cells5. * Niacin promotes healthy skin and makes sure the digestive and nervous systems function properly5.
Minerals in Mushrooms. The focus on the nutritional value of brightly colored fruits and vegetables has unintentionally left mushrooms in the dark. Mushrooms provide a similar number of nutrients as brightly colored fruits and vegetables.
* Selenium is a mineral that works as an antioxidant to protect body cells from damage that might lead to heart disease, some cancers and other diseases of aging5. It also has been found to be important for the immune system and fertility in men6. Many foods of animal origin and grains are good sources of selenium, but mushrooms are among the richest sources of selenium in the produce aisle and provide 8-22 mcg per serving1. This is good news for vegetarians, whose sources of selenium are limited. * Ergothioneine is a naturally occurring antioxidant that also may help protect the body’s cells. Mushrooms provide 2.8-4.9 mg of ergothioneine per serving of white, Portabella or crimini mushrooms7. * Copper helps make red blood cells, which carry oxygen throughout the body. Copper also helps keep bones and nerves healthy1,2,5. * Potassium is an important mineral many people do not get enough of. It aids in the maintenance of normal fluid and mineral balance, which helps control blood pressure. It also plays a role in making sure nerves and muscles, including the heart, function properly. Mushrooms have 267- 407 mg of potassium per serving, which is 9 percent of the Daily Value 1,2,5,8.
PLUS you can increase the vitamin D content!
The Vitamin D Download Mushrooms are the only natural fresh vegetable or fruit with vitamin D; a serving of 4-5 white button mushrooms provides 15 IU. Preliminary research suggests that the ultraviolet light found in sunlight may boost levels of vitamin D in mushrooms. The natural process of “enriching” mushrooms by briefly exposing mushrooms grown in the dark to light for 5 minutes may boost existing vitamin D levels from 15 IU (4 percent of Daily Value) to as much as 100 percent of the Daily Value (400 IU). Currently, the industry is investigating ways to make mushrooms enriched with vitamin D through light enhancement commercially available.
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quote: "People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented," Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.
Is absolute nonsense. The people of Sri Lanka are part of the aboriginal populations that migrated out of Africa and have been black SINCE that migration. But of course, whites just cannot stand to admit that they descend from blacks so they have to make up nonsense to make everything seem equal or that whites are as ancient as blacks when they aren't. South Asia is one of the oldest places first colonized by early humans, including Sri Lanka and therefore it is HIGHLY doubtful that any ancient Sri Lankan turned black from being white in the North because the first Sri Lankans did NOT come from the North. The earliest remains from Sri Lanka are of Australoid aboriginal type people that were the ancestors of those who moved north or at least their close cousins as the earliest populations in the North Also had the same features...
I agree with your comment about aboriginal populations of south Asia retaining dark skin from their African ancestors. Don't know if this article is George Chaplin's own work, or someone else's interpretations thereof, but even it acknowledged the original state of humanity being that of 'dark skin'...
"Humans started in Africa," Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.
Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer...
Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator *eventually* have too little UV...
That doesn't mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own. Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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This article pretty much put Jablonski's article in it's proper place, the circular file.
This is truly amazing stuff. It indicates that like any sophisticated active feedback & control system, each Melanocyte, Fibroblast, and Keratinocyte form a constantly communicating network providing active feedback to each other and between layers for implementing adaptive control for regulating melanin in response to external stimuli, heat regulation, and immunization.
Note that White subject shows no real increase in Melanin density following prolonged irradiation opposed to Black and Latin who show a marked increase.
The "Subjects examined here are; "W" White, "A" Asian, "B" Black
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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meninarmer – at the bottom of page one, it says: melanocytes can produce three distinct types of melanin’s; two types of eumelanin’s, which are associated with dark skin and hair, and pheomelanin which is associated with Red hair and Freckles.
This has me confused; it appears to be saying that pheomelanin though different, is a normal and healthy melanin. From my own observations, thought light-skinned Black people have freckles and Reddish hair, I always thought the trait to be associated primarily with White people – and that the trait in Blacks, was the result of Black/White admixture. But even there, freckled and Red haired White people do not tend to be as pale as Red haired and un-freckled White people.
Then there are the studies that suggest that some Neanderthal’s were red haired - Please Help if you can - what the hell is the deal with Red hair, and how is it different from Blonde hair and Blue eyes.
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Melanin biosynthesis is a complex pathway that appears in highly specialized cells, called melanocytes, within membrane-bound organelles referred to as melanosomes (7) . Melanosomes are transferred via dendrites to surrounding keratinocytes, where they play a critical role in photoprotection. The anatomical relationship between keratinocytes and melanocytes is known as "the epidermal melanin unit" and it has been estimated that each melanocyte is in contact with ~40 keratinocytes in the basal and suprabasal layers (8) .
Several important steps must occur for the proper synthesis and distribution of melanin, as follows (9) .
1. The development of melanocyte precursor cells (melanoblasts) and their migration from the neural crest to peripheral sites Prospective melanocytes, known as melanoblasts, derive from the neural crest beginning in the second month of human embryonic life and migrate throughout the mesenchyme of the developing embryo. They reach specific target sites, mainly the dermis, epidermis, and hair follicles, the uveal tract of the eye, the stria vasculare, the vestibular organ and the endolymphatic sac of the ear, and leptomeninges of the brain. In humans, this migration process takes place between the 10th and the 12th wk of development for the dermis and ~2 wk later for the epidermis (1) .
The survival and migration of neural crest-derived cells during embryogenesis is highly dependent on interactions between specific receptors on the cell surface and their extracellular ligands. For example, steel factor, formerly known as mast cell growth factor, KIT ligand, or stem cell factor (SCF), binds the KIT receptor on melanocytes and melanoblasts. Mutations in the KIT gene decrease the ability of the KIT receptor to be activated by the steel factor and are responsible for at least one type of human piebaldism (10) . See http://albinismdb.med.umn.edu for other examples of genes that regulate pigmentation and, when mutant, are involved in pigmentary disorders.
2. Differentiation of melanoblasts into melanocytes Once melanoblasts have reached their final destinations, they differentiate into melanocytes, which at about the sixth month of fetal life are already established at epidermal-dermal junction sites (1) .
3. Survival and proliferation of melanocytes Melanocytes have been identified within fetal epidermis as early as 50 days of gestation. Dermal melanocytes decrease in number during gestation and virtually disappear by birth, whereas epidermal melanocytes established at the epidermal-dermal junction continue to proliferate and start to produce melanin.
4. Formation of melanosomes and production of melanins Once established in situ, melanocytes start producing melanosomes, highly organized elliptic membrane-bound organelles in which melanin synthesis takes place. They can be detected using electron microscopy (EM) as early as during the fourth month of gestation.
Melanosomes are typically divided into four maturation stages (I–IV) determined by their structure and the quantity, quality, and arrangement of the melanin produced (Fig. 2 ) (11 , 12) . Nascent melanosomes are assembled in the perinuclear region near the Golgi stacks, receiving all enzymatic and structural proteins required for melanogenesis. Stage I melanosomes are spherical vacuoles lacking tyrosinase (TYR) activity (the main enzyme involved in melanogenesis) and have no internal structural components. However, TYR can be detected in the Golgi vesicles, and it has been shown that it is subsequently trafficked to stage II melanosomes. At this point, the presence and correct processing of Pmel17, an important melanosomal structural protein, determine the transformation of stage I melanosomes to elongated, fibrillar organelles known as stage II melanosomes (12 , 13) ; they contain tyrosinase and exhibit minimal deposition of melanin. After this, melanin synthesis starts and the pigment is uniformly deposited on the internal fibrils, at which time the melanosomes are termed as stage III. Their last developmental stage (IV) is detected in highly pigmented melanocytes; these melanosomes are either elliptical or ellipsoidal, electron-opaque due to complete melanization, and have minimal TYR activity. The developmental stages detailed above refer mainly to eu-melanosomes (containing black-brown pigments); however, they are quite similar to pheo-melanosomes (containing yellow-reddish melanin), the only difference being that the latter remain round and are not fibrillar during maturation.
Within melanosomes, at least three enzymes are absolutely required to synthesize different types of melanin. While tyrosinase is responsible for the critical steps of melanogenesis (including the rate-limiting initial step of tyrosine hydroxylation), tyrosinase-related protein 1 (TYRP1) and DOPAchrome tautomerase (DCT) are further involved in modifying the melanin into different types. Besides these, melanosomes contain other melanocyte-specific proteins that have structural functions (e.g., Pmel17, as mentioned above) or probably are involved in regulating the pH within melanosomes , such as P protein- or membrane-associated transporter protein (MATP), or that play as yet unclear roles, such as the melanoma antigen recognized by T cells 1 (MART1) or oculocutaneous albinism-1 (OA-1) protein (14) .
TYR (monophenol, 3,4-ß-dihydroxyphenylalanine oxygen oxidoreductase, EC 1.14.18.1) is a single chain type I membrane glycoprotein catalyzing the hydroxylation of tyrosine to ß-3,4-dihydroxyphenylalanine (DOPA) (which is the initial rate-limiting step in melanogenesis) and the subsequent oxidation of DOPA to DOPAquinone. TYR, TYRP1, and DCT share numerous structural similarities and follow quite similar biosynthetic, processing, and trafficking pathways (15) . Their maturation is assisted by chaperones, calnexin being the most important one due to its involvement in the correct folding of tyrosinase (16 17 18) . The subsequent metabolism of DOPA and its derivatives by various melanocyte-specific enzymes, including TYRP1 and DCT, results in the synthesis of eumelanin, a black-brown pigment. Briefly, 5,6-dihydroxyindole (DHI) melanins are generated from DOPAquinone after several steps of decarboxylation, oxidation, and polymerization. However, in the presence of DCT, the carboxylic acid group of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) is retained when derived from DOPAchrome, and therefore the so-called DHICA melanins are produced. The synthesis of pheomelanin involves the production of cysteinyldopa conjugates from DOPAquinone after the production of DOPA from tyrosine. TYRP1 is important for the correct trafficking of tyrosinase to melanosomes (19) , and DCT also seems to be involved in the detoxification processes (20) taking place within melanosomes.
Melanins are polymorphous and multifunctional biopolymers that include eumelanin, pheomelanin, mixed melanins (a combination of the two), and neuromelanin. Mammalian melanocytes produce two chemically distinct types of melanin pigments: black-brown eumelanin and yellow-reddish pheomelanin (21) . Although they contain a common arrangement of repeating units linked by carbon-carbon bonds, melanin pigments differ from each other with respect to their chemical, structural, and physical properties. Eumelanin is a highly heterogeneous polymer consisting of DHI and DHICA units in reduced or oxidized states, as detailed above; pheomelanin consists mainly of sulfur-containing benzothiazine derivatives (22) . Due to their chemical structure, both eumelanin and pheomelanin are involved in binding to cations, anions, drugs, and chemicals, etc., and therefore play an important protective role within melanocytes (23) . Neuromelanin, which is produced in dopaminergic neurons of the human substantia nigra, can also chelate redox active metals (Cu, Mn, Cr) and toxic metals (Cd, Hg, Pb), and thus protects against their ability to promote neurodegeneration (24) .
Given their complexity, melanosomes can be used as a model to study organelle biogenesis, protein trafficking and processing, organelle movement, and cell-cell interactions (like those occurring during melanin transfer between melanocytes and keratinocytes) (25) . Therefore, even minor changes in the cellular environment affect melanosomes and pigmentation. Numerous intrinsic and extrinsic factors, including body distribution, ethnicity/gender differences, variable hormone-responsiveness, genetic defects, hair cycle-dependent changes, age, UV-R, climate/season, toxin, pollutants, chemical exposure and infestations, are responsible for a whole range of responses in melanosome structure and distribution under different types of stress.
Cutaneous pigmentation is the outcome of two important events: the synthesis of melanin by melanocytes and the transfer of melanosomes to surrounding keratinocytes (26) . Although the number of melanocytes in human skin of all types is essentially constant, the number, size, and manner in which melanosomes are distributed within keratinocytes vary. The melanin content of human melanocytes is heterogeneous not only between different skin types but also between different sites of the skin from the same individual. This heterogeneity is highly regulated by gene expression, which controls the overall activity and expression of melanosomal proteins within individual melanocytes (27) . It has been shown that melanocytes with a low melanin content synthesize TYR more slowly and degrade it more quickly than melanocytes with a higher melanin content and TYR activity (28) . In general, highly pigmented skin contains numerous single large melanosomal particles (0.5–0.8 mm in diameter), which are ellipsoidal and intensely melanotic (stage IV). Lighter pigmentation is associated with smaller (0.3–0.5 mm in diameter) and less dense melanosomes (stages II and III), which are clustered in membrane-bound groups (29) . These distinct patterns of melanosome type and distribution are present at birth and are not determined by external factors (such as sun exposure). They are responsible for the wide variety of skin complexions.
UV-B is responsible for causing the sunburn reaction within the skin and is absorbed mainly by the epidermis and upper dermis. Like UV-A, UV-B stimulates the production of melanin, which constitutes the basis for tanning. UV-B has great potential to induce erythema, and therefore its influence on the skin has been thoroughly investigated in vitro and in vivo (64) . The UV-B portion of the spectrum can promote skin cancer, especially if the exposure has been repeated and prolonged. However, recent studies have shown that the use of narrow-band UV-B (NB-UVB ~311 nm) is a better choice for phototherapy than frequently used psoralen and UV-A therapy (PUVA), which can cause undesirable side effects, including cutaneous cancers (67 , 68 69 70) .
The only known beneficial effect of UV-B is the stimulation of vitamin D synthesis in the epidermis. Vitamin D promotes the absorption of calcium from the intestine and ensures the proper mineralization of bones. However, exposure of just a small area of the body to a small amount of UV-B (5% of that required for erythema) is all that is needed for adequate synthesis of the vitamin D in the skin (64) .
One role of melanin in the skin is to neutralize the ROS generated by a variety of factors, including UV-B (23) , therefore functioning like a natural sunscreen. Until recently it was thought that the higher the melanin content, the less chance of DNA damage resulting from UV-R exposure. In a recent study, the effects of melanin on UV responses in different racial/ethnic groups were investigated for the first time. Despite the general public assumption that dark skin types are UV resistant and therefore not adversely affected by UV, this study showed that even the darkest UV-resistant skin types accumulated significant DNA damage at levels ≤1 minimal erythema dose (MED) (71) . The authors demonstrated that even very low UV exposures cause measurable damage to DNA in all skin types, although it was obvious that the most severe DNA damage was in lightly pigmented skin.
There is no doubt that visual impressions of body form and color are important in interactions within and between human communities. Variation in human skin color is clearly a multifactorial trait with a number of major genetic determinants, several modifier genes, and environmental influences such as exposure to UV-R and gender effects. The pathological role of pigmentation originates mainly from the fact that melanin pigments serve not only as the major determinant of skin color but also as the major source of skin protection against UV-R, preventing sun-induced skin damage as well as skin cancer development. It is well known that repeated exposures to UV-R during an individual’s lifetime are responsible not only for skin aging, but also for the appearance of skin cancer. Various types of skin cancers are responsible today for 50% of all new cancer cases in the U.S. Melanoma, which accounts for > 85% of all skin cancer deaths within the U.S., is the sixth most common type of cancer in men and the seventh in women; over the past 20 years the incidence of melanomas has more than doubled.
Melanogenesis is a highly regulated process that is modified by transcriptional, translational, and post-translational mechanisms. Melanin production results from strong cellular and molecular connections between all cell populations in the skin, the key players being fibroblasts, keratinocytes, and melanocytes. Minor changes in the cellular physiology of the skin can dramatically affect pigment production in positive or negative manners.
The purpose of this review was to provide an overview of the mechanisms by which external or internal factors up-regulate melanin production in either transitory (such as in pregnancy) or permanent (such as aging) fashion. The action of UV-R has been extensively investigated, and there is a great amount of literature available to explain its mechanism of action on the skin and its involvement in hyperpigmentation. Those studies are the basis for research focused on understanding the contribution of sun exposure to the appearance of solar lentigines and other age-related factors in the hyperpigmentation so often seen in older individuals.
The mechanisms of actions of other factors on the skin are less completely understood, such as those involving drugs or certain compounds in increasing melanin production, but studies are ongoing in this direction, trying to provide a scientific rationale for such effects seen in different clinical treatments.
quote:Originally posted by Mike111: meninarmer – at the bottom of page one, it says: melanocytes can produce three distinct types of melanin’s; two types of eumelanin’s, which are associated with dark skin and hair, and pheomelanin which is associated with Red hair and Freckles.
This has me confused; it appears to be saying that pheomelanin though different, is a normal and healthy melanin. From my own observations, thought light-skinned Black people have freckles and Reddish hair, I always thought the trait to be associated primarily with White people – and that the trait in Blacks, was the result of Black/White admixture. But even there, freckled and Red haired White people do not tend to be as pale as Red haired and un-freckled White people.
Then there are the studies that suggest that some Neanderthal’s were red haired - Please Help if you can - what the hell is the deal with Red hair, and how is it different from Blonde hair and Blue eyes.
You may find this study on Hair Color and Diet of interest. The Neanderthal's may have been red headed primarily due to their low tyrosine diets.
quote:Originally posted by meninarmer: Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
She's stealing and repackaging my stuff! What she is "implying" is that UV exposure led to Albinism, which in turn created havoc on European immunization and productive capabilities.
Wow lol, so much ignorance.
What she is actually implying here, is that in Africa under the intense ultraviolet light, original humans had to be dark in order to protect from the intense ultraviolet light or else the over UV exposure can age the skin and damage the DNA molecule, which makes it harder to build a fetus, and causes skin cancer etc..
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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^ LOL, can't you READ junior, or if a picture is worth a thousand words, can't you see which races ADAPT in real time to environmental exposure, and which ONE doesn't. While what you say is ALMOST true, you miss the point that the absence of this control and protection mechanism is a very serious affair and leaves Europeans WIDE OPEN for susceptibility to sun burn, skin cancer, and drastic reproductive mutations. Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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Hey, you're the imbecile who thought she was implying UV exposure causes albinism after reading the following...
quote: "Humans started in Africa," Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.
Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by MindoverMatter718: Hey, you're the imbecile who thought she was implying UV exposure causes albinism after reading the following...
quote: "Humans started in Africa," Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.
Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
UV induced DNA damage is a very likely candidate for the introduction of Albinism. Albinism is very likely the cause of the introduction of the European (sic) "Race", not some "evolved" magical gene or as Jablonski proposes. sweat.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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Of course all the while blatantly ignoring the immediate following, in which I see Explorer has already pointed out..
quote:On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don't get enough ultraviolet light, we're less likely to survive to reproductive age to produce strong-boned babies.
Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator eventually have too little UV......
Hooray For Melanin
That doesn't mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own.
Successive mutations created successive generations of lighter and lighter people as they moved north.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by meninarmer: UV induced DNA damage is a very likely candidate for the introduction of Albinism.
Lol, so now people can become albinos? But aren't albinos born this way?
I guess that you're saying UV must be getting through mommies belly and causing these babies to become albinos?
quote:Originally posted by meninarmer: Albinism is very likely the cause of the introduction of the European (sic) "Race", not some "evolved" magical gene or as Jablonski proposes. sweat.
Poor you and your feeble mind. What's actually funny is you thought this article somehow helped your theory. Lol.
Where did you come to the idea that Jablonski said Europeans turned white because of sweat? Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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Skin cancer also occurs in Norwegian whites. Therefore, the UV levels are not at all as low as you propose. More reading and less blabbing please.
Look at this NONSENSE.
Jablonski writes; She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."
This nonsense must have been published in Discover or one of those other pseudo-science monthlies. 2,500 years ago, my ancestors were most likely the same hue as I am today. Where does Jablonski offer any real proof of her nonsensical statements?
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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^^That I propose; or that of which the scientific community proposes; the one you actually thought agreed with you? Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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I care not that Jablonski's nonsense is in obvious contradiction. The REAL scientific data posted by real scientists is in line with reality, but you will likely not see it published in Discover magazine.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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So far you've failed in showing any contradictions.
All the while being caught in a million of your own.
Therefore this article like everything else, debunks your albinism theory yet again.
quote:"Humans started in Africa," Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.
Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.
On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don't get enough ultraviolet light, we're less likely to survive to reproductive age to produce strong-boned babies.
Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator eventually have too little UV......
Hooray For Melanin
That doesn't mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own.
Successive mutations created successive generations of lighter and lighter people as they moved north.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by meninarmer: Look at this NONSENSE.
Jablonski writes; She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."
This nonsense must have been published in Discover or one of those other pseudo-science monthlies. 2,500 years ago, my ancestors were most likely the same hue as I am today. Where does Jablonski offer any real proof of her nonsensical statements? [/qb]
Obviously she is talking about some families who moved from place to place traveling (North, South etc..) not everybody absolutely in the world.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by meninarmer: Look at this NONSENSE.
Jablonski writes; She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."
This nonsense must have been published in Discover or one of those other pseudo-science monthlies. 2,500 years ago, my ancestors were most likely the same hue as I am today. Where does Jablonski offer any real proof of her nonsensical statements?
Obviously she is talking about some families who moved from place to place traveling (North, South etc..) not everybody absolutely in the world. [/QB]
Of course it's not everyone. Only Europeans. Africans are the same color today they were 10,000 years ago. Obviously she is speaking more about admixed populations such as India. Yet, she still fails to offer any real evidence for her narrow European claim, or why Europeans share the same genetic history as Albinos.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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Boys, boys; There is no need to argue. The truth or lie of Jablonski's theory can be easily TESTED.
Between 332 B.C. when Alexander took Egypt, and about 600 A.D. when the Turks began their ascension: Millions upon Millions of White people, from every Asian locality, found their way to North Africa and the middle-east, to seek their fortunes.
Since the timeframe is the same as that required by Jablonski's theory, all we have to do to test Jablonski's theory, is to see if any of them are still White. (Of course we must allow for those who are the result of admixture).
So everybody; lets see if we can find pictures of any White North Africans and Middle-easterners.
Posts: 22721 | Registered: Oct 2005
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quote:Originally posted by meninarmer: Skin cancer also occurs in Norwegian whites. Therefore, the UV levels are not at all as low as you propose. More reading and less blabbing please.
Look at this NONSENSE.
Jablonski writes; She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."
This nonsense must have been published in Discover or one of those other pseudo-science monthlies. 2,500 years ago, my ancestors were most likely the same hue as I am today. Where does Jablonski offer any real proof of her nonsensical statements?
The nonsense in that statement is that families as a unit cannot be traced over 2,500 years. Not to mention that families consist of various people of different backgrounds intermarrying and therefore adding different ancestries every generation, which means tying that family to any one place historically impossible over 2000 years ago.
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quote:Originally posted by Mike111: Boys, boys; There is no need to argue. The truth or lie of Jablonski's theory can be easily TESTED.
Between 332 B.C. when Alexander took Egypt, and about 600 A.D. when the Turks began their ascension: Millions upon Millions of White people, from every Asian locality, found their way to North Africa and the middle-east, to seek their fortunes.
Since the timeframe is the same as that required by Jablonski's theory, all we have to do to test Jablonski's theory, is to see if any of them are still White. (Of course we must allow for those who are the result of admixture).
So everybody; lets see if we can find pictures of any White North Africans and Middle-easterners.
MOverM Is just so convinced of the nonsensical articles he posts that provide no real proof of their claims. Even with photos their linage cannot be traced back 2500 years. Also, whites who live in Northern Africa would be susceptible to rapid skin aging and genetic defect as can be seen in this Berber woman who is perhaps 50 years old. Sun exposure has made her no darker, nor does the infant she is holding show any marked signs of acquiring addition melanin density.
This correlates well with the results of this study which conclusively shows Whites acquire no increase in melanin density when exposed for prolonged periods of UV radiation.
Europeans have always be fascinated white the concept of Whites in early Africa. So much so that in 1867 the juvenile market writer, William Graydon's fantasy novel, The White King Of Africa, about a white man who ruled a tribe of African cannibals became a bestseller in England, Europe, and America. The book then went on to form Edgar Burroughs Tarzan fantasy.
Posts: 3595 | From: Moved To Mars. Waiting with shotgun | Registered: Dec 2006
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MindoverMatter718 - meninarmer's proof seems conclusive. Shall we agree that Jablonski's theory is total horsesh1t, or will you produce proof to the contrary?Posts: 22721 | Registered: Oct 2005
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Gringo is right, Europeans are not albinos. They are products of Bay Area Chinese-looking European Asians that mixed with incoming Forest Negro Pygmy-looking Africans. Ain't that right gringo?! LOL
Posts: 4165 | From: jamaica | Registered: May 2008
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quote:Originally posted by meninarmer: Sun exposure has made her no darker, nor does the infant she is holding show any marked signs of acquiring addition melanin density.
This correlates well with the results of this study which conclusively shows Whites acquire no increase in melanin density when exposed for prolonged periods of UV radiation.
They turned white due to low UV levels, hence obviously they lost natures sun screen (dark skin) hence they are now susceptible to harmful UV rays when in higher UV environments that darker skin protected against.
Since as explained lighterskin is evolved to allow UV to penetrate the skin under darker cloudier skies to synthesize and produce Vitamin D.
Darkerskinned populations are not able to acquire this UV under darker skies (hence why darkskinned populations suffer from Vitamin D deficiencies in northern latitudes), as lighterskinned humans are. Plain and simple.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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All evidence seems to be on my side; not any of yours.
Darkskin is natures sunscreen; hence blocks out the sun, and in northern latitudes, darker skinned populations need to take Vitamin D supplements, or have an immense Vitamin D intake through diet.
THE COLOR IN BONES - WHY BLACK WOMEN ARE AT HIGHER RISK
A variety of factors can cause calcium and vitamin D deficiency in African-American women. *****The high melanin content in darker skin reduces the skin's ability to produce vitamin D from sunlight.**** ****In fact, experts note that people with darker skin may need 20 to 30 times as much exposure to sunlight as fair-skinned individuals to generate the same amount of vitamin D.****** Inadequate intake of vitamin D in diet is another factor. Studies confirm that African Americans consume the lowest amounts of vitamin D from food alone among different ethnicities. According to the National Institutes of Health (NIH), as many as 75 percent of African Americans are lactose intolerant, possibly further limiting the consumption of calcium and vitamin D fortified dairy products.
For centuries, Inuit living in Canada's Arctic spent months without sunlight, and lifetimes wearing thick, fur clothing that blocked the sunlight from their dark skin.
Mother Nature provided vitamin D in other ways. Instead of making it through sun exposure, the Inuit got a healthy dose from traditional foods that happen to be rich in vitamin D: the skin of Arctic char; seal liver; the yolks of bird and fish eggs; and seal, walrus and whale blubber.
But as the Arctic has changed, so have eating habits. While seal and char (trout) are still staples in Nunavut's isolated communities, walrus and whale consumption have been in decline for 30 years.
The result is ****vitamin D deficiency***, which surfaces as ***rickets*** , a disease most Canadians might be surprised to hear still exists in Canada. Thirty-one new cases of rickets were discovered in the first five years of Nunavut's creation.
4. Groups at risk of not obtaining adequate amounts of vitamin D include:
· the elderly;
· exclusively breast-fed babies;
· individuals with dark skin pigmentation;
· individuals with limited skin exposure to the sun (e.g. housebound, or those who wear clothing covering most of the skin for cultural/religious reasons); and
· those who during the winter are living above 37 degrees latitude (Canada and Northern US).Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by Horet: Why is this black supremacist trash allowed to propogate so much here?
What makes this discussion "black supremist"?
The articles being discussed were all written by Europeans. Are you saying whites are racist?
.
Because it's largely about lauding the idiotic black supremacist rhetoric on how whites are some sort albinic mutants?
Posts: 148 | Registered: Jan 2009
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meninarmer - What we are dealing with here, is at once pernicious and pervasive. Note this quote from Oregon State Univ.
"Linus Pauling Institute (OSU) Quote: One U.S. study reported that 42% of African American women between 15 and 49 years of age were vitamin D deficient compared to 4% of White women"
Isn't it customary to give the name of the study and it's author when citing it? Without knowing the specifics, my guess would be that this is a totally bogus study, much like the one cited by MindoverMatter718, which was done by a Drug company trying to sell their product.
And if there is a problem with vitamin D deficiency, it is easily explained by two things that we already know have an impact on many Black communities - Nutrition and Obesity.
Obesity: Obesity increases the risk of vitamin D deficiency. Once vitamin D is synthesized in the skin or ingested, it is deposited in body fat stores, making it less bioavailable to people with large stores of body fat.
So why did I say "pernicious and pervasive"? Because this is just another example of White people using their power of information to misinform Black people. Before they used guns and dogs, now they use information. The tool is different, the intent is not. BTW - a visit to the National Medical Association (the association of Black doctors), fails to turn up any mention of this supposed "Health Crisis".
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quote:Originally posted by Mike111: "Linus Pauling Institute (OSU) Quote: One U.S. study reported that 42% of African American women between 15 and 49 years of age were vitamin D deficient compared to 4% of White women"
Mike,
The high melanin content in darker skin reduces the skin's ability to produce vitamin D from sunlight in northern latitudes. This is a biological fact.
quote:Originally posted by Mike111: Isn't it customary to give the name of the study and it's author when citing it? Without knowing the specifics, my guess would be that this is a totally bogus study, much like the one cited by MindoverMatter718, which was done by a Drug company trying to sell their product.
Speaks for itself. To you I guess they're all trying to sell their products..
1. There is strong evidence of the harms of exposure to UV radiation from the sun and other sources, including skin cancer, melanoma and some cataracts. Based on expert consensus, sun protection is required when the UV index is 3 (moderate) or higher.
2. There is strong evidence of the benefits of adequate vitamin D status on musculoskeletal health and prevention of fractures in the elderly. There is also a growing body of evidence that vitamin D may have beneficial effects on some types of cancer, in particular colorectal cancer. Experts are concerned that vitamin D status may be too low in the general population to achieve these health benefits.
3. Vitamin D is obtained through skin exposure to UVB radiation, and also through diet (particularly fortified foods) and supplementation. To minimize the health risks associated with UVB radiation exposure while maximizing the potential benefits of optimum Vitamin D status, supplementation and small amounts of sun exposure are the preferred methods of obtaining vitamin D.
The known risks associated with unprotected UVB exposure must be weighed against its benefits as a source of vitamin D. For example, it is possible that just a few minutes a day of unprotected sun exposure will increase vitamin D status, but for some, may also increase the risk of skin damage. Factors such as age, diet, skin pigmentation, geographic location and intensity of the sun will affect the amount of sun exposure needed to produce adequate vitamin D. More research is needed in this area before any more specific recommendations can be made.
4. Groups at risk of not obtaining adequate amounts of vitamin D include:
· the elderly;
· exclusively breast-fed babies;
· individuals with dark skin pigmentation;
· individuals with limited skin exposure to the sun (e.g. housebound, or those who wear clothing covering most of the skin for cultural/religious reasons); and
· those who during the winter are living above 37 degrees latitude (Canada and Northern US).Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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Horet - So far, everyone with a point of view on this matter has provided some sort of logic or documentation to support their position. Even MindoverMatter718 provided something, weak as it was.
Though I am sure that you are the brightest Whiteboy to ever walk the planet, I would still be nice if you were to provide some manner of support for your no-doubt brilliant position.
Posts: 22721 | Registered: Oct 2005
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Mike, The high melanin content in darker skin reduces the skin's ability to produce vitamin D from sunlight in northern latitudes. This is a biological fact.
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^Ad hominem remarks do nothing for your erroneous theory.
Face facts, or get lost.
Darkskin is natures sunscreen; hence blocks out the sun, and in northern latitudes, darker skinned populations need to take Vitamin D supplements, or have an immense Vitamin D intake through diet.
In turn lighterskin allows for UV to penetrate the skin in northern latitudes under darker skies; where there is less sun, and hence lighterskin people are not as much at risk as darkerskinned populations for Vitamin D deficiencies in northern latitudes.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by Mike111: Horet - So far, everyone with a point of view on this matter has provided some sort of logic or documentation to support their position. Even MindoverMatter718 provided something, weak as it was.
Though I am sure that you are the brightest Whiteboy to ever walk the planet, I would still be nice if you were to provide some manner of support for your no-doubt brilliant position.
Cut the sarcastic BS. What are you trying to prove with all of this talk about melanin?
Posts: 148 | Registered: Jan 2009
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