Human populations feature a broad palette of skin tones. But until now, few genes have been shown to contribute to normal variation in skin color, and these had primarily been discovered through studies of European populations.
Please note: comments and debunking of this nonsense study,
will normally be in Blue text on White background
|A Penn-led team identified new genes associated with skin color variations. Their study of more than 2,000 Africans from diverse ethnic backgrounds sheds light on ancient human migrations, the biology of skin pigmentation and health and disease risks [Credit: Alessia Ranciaro and Simon Thompson]|
Now, a study of diverse African groups led by University of Pennsylvania geneticists has identified new genetic variants associated with skin pigmentation. The findings help explain the vast range of skin color on the African continent, shed light on human evolution and inform an understanding of the genetic risk factors for conditions such as skin cancer. "We have identified new genetic variants that contribute to the genetic basis of one of the most strikingly variable traits in modern humans," said Sarah Tishkoff, a Penn Integrates Knowledge Professor and the David and Lyn Silfen University Professor in Genetics and Biology with appointments in the Perelman School of Medicine and School of Arts and Sciences. "When people think of skin color in Africa most would think of darker skin, but we show that within Africa there is a huge amount of variation, ranging from skin as light as some Asians to the darkest skin on a global level and everything in between. We identify genetic variants affecting these traits and show that mutations influencing light and dark skin have been around for a long time, since before the origin of modern humans."
The findings are published in the journal Science. Tishkoff, senior author, collaborated with first author and lab member Nicholas Crawford, a postdoctoral fellow, and a multi-institutional, international team. Tishkoff has long studied the genetics of African populations, looking at traits such as height, lactose tolerance, bitter-taste sensitivity and high-altitude adaptation. Skin color emerged as a trait of interest from her experience working on the continent and seeing the diversity present across groups. "Skin color is a classic variable trait in humans, and it's thought to be adaptive," Tishkoff said. "Analysis of the genetic basis of variation in skin color sheds light on how adaptive traits evolve, including those that play a role in disease risk." Both light and dark skin pigmentations confer benefits: Darker skin, for example, is believed to help prevent some of the negative impacts of ultraviolet light exposure, while lighter skin is better able to promote synthesis of vitamin D in regions with low ultraviolet light exposure.
Comment - this is an old Albino lie that has been
debunked many times by scientific study and anecdotally.
In 2004, Nina G. Jablonski - then of the Department of Anthropology, California Academy of Sciences; published a study entitled "THE EVOLUTION OF HUMAN SKIN AND SKIN COLOR" which declared that White skin developed in Europeans because of a lack of vitamin "D". (She is now at Pennsylvania State University).
Though Nina G. Jablonski's nonsense was disproved by common sense and a myriad of related studies, it was officially discredited by Ashley H. Robins study of 2009; which said that vitamin "D" had nothing to do with it! (The American Journal of Physical Anthropology).
Many additional proofs debunking the nonsense that pale skin
(Albinism) aids vitamin D absorption are at this link:
To objectively capture the range of skin pigmentation in Africa, Tishkoff and colleagues used a color meter to measure the light reflectance of the skin of more than 2,000 Africans from ethnically and genetically diverse populations. They took the measurement from the inner arm, when sun exposure is minimal. The measurements can be used to infer levels of the skin pigment melanin. They obtained a range of measurements; the darkest skin was observed in Nilo-Saharan pastoralist populations in eastern Africa, and the lightest skin was observed in San hunter-gatherer populations in southern Africa.
The researchers obtained genetic information from nearly 1,600 people, examining more than 4 million single nucleotide polymorphisms across the genome, places where the DNA code may differ by one "letter." From this dataset the researchers were able to do a genome-wide association study and found four key areas of the genome where variation closely correlated with skin color differences. The region with the strongest associations was in and around the SLC24A5 gene, one variant of which is known to play a role in light skin color in European and some southern Asian populations and is believed to have arisen more than 30,000 years ago. This variant was common in populations in Ethiopia and Tanzania that were known to have ancestry from southeast Asia and the Middle East, suggesting it was carried into Africa from those regions and, based on its frequency, may have been positively selected.
This one is really silly, these Albinos are actually suggesting that their Albinism (which they call "Light Skin") was created in southeast Asia and the Middle East and brought BACK into Africa. This is of course a play on the expected ignorance of the general population to not know that Europeans, Southeast Asians, Middle Easterners, and ALL people were originally Black.
Neolithic = 10,200 B.C. to 4,500 B.C.
Another region, which contains the MFSD12 gene, had the second strongest association to skin pigmentation. This gene is expressed at low levels in depigmented skin in individuals with vitiligo, a condition where the skin loses pigment in some areas. "I still remember the 'ah ha!' moment when we saw this gene was associated with vitiligo," said Crawford. "That's when we knew we'd found something new and exciting." The team found that mutations in and around this gene that were associated with dark pigmentation were present at high frequencies in populations of Nilo-Saharan ancestry, who tend to have very dark skin, as well as across sub-Saharan populations, except the San, who tend to have lighter skin. They also identified these variants, as well as others associated with dark skin pigmentation, in South Asian Indian and Australo-Melanesian populations, who tend to have the darkest skin coloration outside of Africa.
"The origin of traits such as hair texture, skin color and stature, which are shared between some indigenous populations in Melanesia and Australia and some sub-Saharan Africans, has long been a mystery." Tishkoff said. "Some have argued it's because of convergent evolution, that they independently evolved these mutations, but our study finds that, at genes associated with skin color, they have the identical variants associated with dark skin as Africans.
Another Lie! Pale Skin, Straight Hair, Blonde and Red hair:
Blue, Green, and Gray eyes,
are ALL indicators of different levels Albinism.
"Our data are consistent with a proposed early migration event of modern humans out of Africa along the southern coast of Asia and into Australo-Melanesia and a secondary migration event into other regions. However, it is also possible that there was a single African source population that contained genetic variants associated with both light and dark skin and that the variants associated with dark pigmentation were maintained only in South Asians and Australo-Melanesians and lost in other Eurasians due to natural selection."
Here again, the Albinos are saying that they (Albinos), are Albinos by choice. They feel that they are "Prettier". And perhaps they are; to themselves and Blacks under their Hegemony, who are a captive audience to their lies and Propaganda. We sometimes wonder if the real purpose of conquering the World and killing all of those people, was just to get validation for that pathetic bit of lying Hubris. Of course no one chooses to be diseased, and if that was indeed their choice, which it COULD have been:
On the other hand, this is how Blacks free of Albino indoctrination and Propaganda view their Blackness.
The travels of Marco Polo ("The description of the world)
Also of interest was that genetic variants at MFSD12, OCA2, and HERC2 associated with light skin pigmentation were at highest frequency in the African San population, which has the oldest genetic lineages in the world, as well as in Europeans.
For some time, we Black researchers, have wondered if light skin in (Supposedly) unmixed Blacks like the San, was due to normal environmental variation, the result of surreptitious mating, or a tinge of Albinism. This study clearly indicates a tinge of Albinism. But is that tinge of Albinism naturally occurring, like in Blonde Pacificans, or is it due to Afrikaner Rape?
These two tables tell the real meaning of those Genes:
This is what Albino people hide, and dread admitting.
|In a first-of-its-kind study, University of Pennsylvania researchers studied the genetics behind skin pigmentation of diverse African populations, finding new genetic variants associated with skin color. Here, senior research scientist Alessia Ranciaro measures the skin reflectance of a man from a Nilo-Saharan group. Members of this population tend to have very dark skin pigmentation [Credit: Tishkoff lab]|
MFSD12 is highly expressed in melanocytes, the cells that produce melanin. To verify the gene's role in contributing to skin pigmentation, the researchers blocked expression of the gene in cells in culture and found an increase in production of eumelanin, the pigment type responsible for black and brown skin, hair and eye color. Knocking out the gene in zebrafish caused a loss of cells that produce yellow pigment. And in mice, knocking out the gene changed the color of their coat from agouti, caused by hairs with a red and yellow pigment, to a uniform gray by eliminating production of pheomelanin, a type of pigment also found in humans. "Apart from one study showing that MFSD12 was associated with vitiligo lesions, we didn't know much else about it," said Crawford, "so these functional assays were really crucial."
"We went beyond most genome-wide association studies to do functional assays," Tishkoff said, "and found that knocking out MFSD12 dramatically impacted the pigmentation of fish and mice. It's pointing to this being a very conserved trait across species. "We don't know exactly why, but blocking this gene causes a loss of pheomelanin production and an increase in eumelanin production," Tishkoff added. "We also showed that Africans have a lower level of MFSD12 expression, which makes sense, as low levels of the gene means more eumelanin production." A collaborator on the work, Michael Marks, a professor in the departments of Pathology & Laboratory Medicine and of Physiology at Children's Hospital of Philadelphia and at Penn Medicine, demonstrated that the MFSD12 gene influences eumelanin pigmentation in a novel manner. Unlike other pigmentation genes, which are expressed mainly in melanosomes, the organelle where melanin is produced, MFSD12 is expressed in lysosomes, a distinct organelle from the melanosomes that produce eumelanin.
"Our results suggest there must be some kind of as-yet-uncharacterized form of cross-talk between lysosomes and the melanosomes that make eumelanins," Marks said. "Figuring out how this works might provide new ideas for ways to manipulate skin pigmentation for therapeutic means. "In addition," Marks said, "the fact that loss of MFSD12 expression had opposite effects on the two types of melanins, increasing eumelanin production while suppressing pheomelanin, suggests that melanosomes that make pheomelanins might be more related to lysosomes than those that make eumelanin."
Additional associations with skin color were found in the OCA2 and HERC2 genes, which have been linked with skin, eye and hair color variation in Europeans, though the mutations identified are novel. Mutations in OCA2 also cause a form of albinism that is more common in Africans than in other populations. The researchers observed genetic variants in a neighboring gene, HERC2, which regulates the expression of OCA2. Within OCA2, they identified a variant common in Europeans and San that is associated with a shorter version of the protein, with an altered function. They observed a signal of balancing selection of OCA2, meaning that two different versions of the gene have been maintained, in this case for more than 600,000 years. "What this tells us," Tishkoff said, "is there is likely some selective force maintaining these two alleles. It is likely that this gene is playing a role in other aspects of human physiology which are important."
A final genetic region the researchers found to be associated with skin pigmentation included genes that play a role in ultraviolet light response and melanoma risk. The top candidate gene in the region is DDB1, involved in repairing DNA after exposure to UV light. "Africans don't get melanoma very often," Tishkoff said. "The variants near these genes are highest in populations who live in areas of the highest ultraviolet light intensity, so it makes sense that they may be playing a role in UV protection." The mutations identified by the team play a role in regulating expression of DDB1 and other nearby genes. "Though we don't yet know the mechanism by which DDB1 is impacting pigmentation, it is of interest to note that this gene, which is highly conserved across species, also plays a role in pigmentation in plants such as tomatoes," said Tishkoff.
The team saw evidence that this region of the genome has been a strong target of natural selection outside of Africa; mutations associated with light skin color swept to nearly 100 percent frequency in non-Africans, one of few examples of a "selective sweep" in all Eurasians; the age of the selective sweep was estimated to be around 60,000 to 80,000 years old, around the time of migration of modern humans out of Africa.
These silly lying Albinos are depending HEAVILY on the ignorance of the general population in not knowing the normal appearance of the World’s people.
One additional takeaway from this work is a broader picture of the evolution of skin color in humans. Most of the genetic variants associated with light and dark pigmentation from the study appear to have originated more than 300,000 years ago, and some emerged roughly 1 million years ago, well before the emergence of modern humans. The older version of these variants in many cases was the one associated with lighter skin, suggesting that perhaps the ancestral state of humans was moderately pigmented rather than darkly pigmented skin. "If you were to shave a chimp, it has light pigmentation," Tishkoff said, "so it makes sense that skin color in the ancestors of modern humans could have been relatively light. It is likely that when we lost the hair covering our bodies and moved from forests to the open savannah, we needed darker skin. Mutations influencing both light and dark skin have continued to evolve in humans, even within the past few thousand years."
On the surface that sounds somewhat reasonable, until you test it with known data. Regarding Fur, Only those of the Horse family, including Zebra, and Humans, use sweat as the primary means of temperature regulation - NOT Chimps. The modern horse is 5 million years old. No one seems to know the age of modern Chimps, but it is less than 5 million years. Likewise, no one seems to know the age of modern humans, but it seems to be about 400,000 years.
Question: If Primate Fur gave way to Black skin and sweating for life on the Savannah, then why do Zebras still have Fur, when they live on the Savannah, along with some Chimps and Baboons, and they are all much older than Modern Man?
See the study: Savanna Chimpanzees, Pan troglodytes verus, Hunt with Tools
Tishkoff noted that the work underscores the diversity of African populations and the lack of support for biological notions of race.
"Many of the genes and new genetic variants we identified to be associated with skin color may never have been found outside of Africa, because they are not as highly variable," Tishkoff said. "There is so much diversity in Africa that's not often appreciated. There's no such thing as an African race. We show that skin color is extremely variable on the African continent and that it is still evolving. Further, in most cases the genetic variants associated with light skin arose in Africa."
Here they walk back their nonsense about Southeast Asia and the Middle East.
Want some African Diversity?
Here, lets try some Ethiopians
Miss Scandinavia? Miss Germany? Miss Ireland? Miss Russia?
Peaches-n-Cream complexion, "Long Natural Blonde Hair", Blue eyes..... What else could she be?
Source: University of Pennsylvania [October 12, 2017]
Read more at https://archaeologynewsnetwork.blogspot.com/2017/10/genes-responsible-for-diversity-of.html#Rr2o2SgGLDoIm4hk.99
Nicholas G. Crawford, Derek E. Kelly, Matthew E. B. Hansen, et al.
Science 17 Nov 2017: Vol. 358, Issue 6365, eaan8433
Skin color varies among human populations and is thought to be under selection, with light skin maximizing vitamin D production at higher latitudes and dark skin providing UV protection in equatorial zones. To identify the genes that give rise to the palette of human skin tones, Crawford et al. applied genome-wide analyses across diverse African populations (see the Perspective by Tang and Barsh). Genetic variants were identified with likely function in skin phenotypes. Comparison to model organisms verified a conserved function of MFSD12 in pigmentation. A global genetic panel was used to trace how alleles associated with skin color likely moved across the globe as humans migrated, both within and out of Africa.
Science, this issue p. eaan8433; see also p. 867
Variation in pigmentation among human populations may reflect local adaptation to regional light environments, because dark skin is more photoprotective, whereas pale skin aids the production of vitamin D. Although genes associated with skin pigmentation have been identified in European populations, little is known about the genetic basis of skin pigmentation in Africans.
Genetically and phenotypically diverse African populations are informative for mapping genetic variants associated with skin pigmentation. Analysis of the genetics of skin pigmentation in Africans informs upon melanocyte biology and the evolution of skin pigmentation in humans.
We observe extensive variation in skin pigmentation in Africa, with lowest melanin levels observed in southern African San hunter-gatherers and highest levels in East African Nilo-Saharan pastoralists. A genome-wide association study (GWAS) of 1570 Africans identified variants significantly associated with skin pigmentation, which clustered in four genomic regions that together account for almost 30% of the phenotypic variation.
The most significantly associated single-nucleotide polymorphisms were at SLC24A5, a gene associated with pigmentation in Europeans. We show that SLC24A5 was introduced into East Africa >5 thousand years ago (ka) and has risen to high frequency.
The second most significantly associated region is near the gene MFSD12. Using in vitro and in vivo analyses, we show that MFSD12 codes for a lysosomal protein that modifies pigmentation in human melanocytes, with decreased MFSD12 expression associated with darker pigmentation. We also show that genetic knockouts of MFSD12 orthologs affect pigmentation in both zebrafish and mice.
A third highly associated region encompasses a cluster of genes that play a role in ultraviolet (UV) response and DNA damage repair. We find the strongest associations in a regulatory region upstream of DDB1, the gene encoding damage-specific DNA binding protein 1, and that these variants are associated with increased expression of DDB1. The alleles associated with light pigmentation swept to near fixation outside of Africa due to positive selection, and we show that these lineages coalesce ~60 ka, corresponding with the time of migration of modern humans out of Africa.
The fourth significantly associated region encompasses the OCA2 and HERC2 loci. We identify previously uncharacterized variants at HERC2 associated with the expression of OCA2. These variants arose independently from eye and skin pigmentation–associated variants in non-Africans. We also identify variants at OCA2 that are correlated with alternative splicing; alleles associated with light pigmentation are correlated with a shorter transcript, which lacks a transmembrane domain.
We identify previously uncharacterized genes and variants associated with skin pigmentation in ethnically diverse Africans. These genes have diverse functions, from repairing UV damage to playing important roles in melanocyte biology. We show that both dark and light pigmentation alleles arose before the origin of modern humans and that both light and dark pigmented skin has continued to evolve throughout hominid history. We show that variants associated with dark pigmentation in Africans are identical by descent in South Asian and Australo-Melanesian populations. This study sheds light on the evolutionary history, and adaptive significance, of skin pigmentation in humans.
|A genome-wide association study (GWAS) and functional assays illuminate the genetic basis of pigmentation in Africa. It identified four genomic regions associated with skin pigmentation in Africa. Functional assays in melanocytes, zebrafish, and mice characterized their impact on skin pigmentation. Evolutionary genetic analyses revealed that most derived variants evolved before the origin of modern humans. Ma, million years ago.|
Despite the wide range of skin pigmentation in humans, little is known about its genetic basis in global populations. Examining ethnically diverse African genomes, we identify variants in or near SLC24A5, MFSD12, DDB1, TMEM138, OCA2, and HERC2 that are significantly associated with skin pigmentation. Genetic evidence indicates that the light pigmentation variant at SLC24A5 was introduced into East Africa by gene flow from non-Africans. At all other loci, variants associated with dark pigmentation in Africans are identical by descent in South Asian and Australo-Melanesian populations. Functional analyses indicate that MFSD12 encodes a lysosomal protein that affects melanogenesis in zebrafish and mice, and that mutations in melanocyte-specific regulatory regions near DDB1/TMEM138 correlate with expression of ultraviolet response genes under selection in Eurasians.
(Their point being that if human skin was originally light, then they can't be Albinos!).
This silliness proves that when it comes to Race, Albinos have no sense of logic. We already know that the Earths creatures have the ability to EVOLVE and ADJUST to changing environments and conditions. And we know that each adjustment the body makes requires energy. Logically then, if a body gets protection from the Suns UV Rays with its MELANIN saturated FUR, it would be a waste of ENERGY to also saturate the underlying Skin with Melanin.
Of course the REVERSE would also have to be true: Polar Bears, which have WHITE Fur year-round, have BLACK Skin under their Fur.
Wiki: "Polar bear fur consists of a layer of dense underfur and an outer layer of guard hairs, which appear white to tan but are actually transparent. Two genes that are known to influence melanin production, LYST and AIM1, are both mutated in polar bears, possibly leading to the absence on this pigment in their fur. The guard hair is 5–15 cm (2–6 in) over most of the body. Polar bears gradually moult from May to August, but, unlike other Arctic mammals, they do not shed their coat for a darker shade to provide camouflage in summer conditions. The hollow guard hairs of a polar bear coat were once thought to act as fiber-optic tubes to conduct light to its black skin, where it could be absorbed; however, this hypothesis was disproved by a study in 1998."
Arctic Foxes which have WHITE Fur in the Sunless Winter; change to BROWN Fur along the back, with light gray fur around the abdomen in summer.
Their problem is not that they have White Skin in of itself. Their problem is that they have WHITE SKIN AND NO FUR! And the DISEASE of ALBINISM has robbed them of the ability to make enough MELANIN in their SKIN to COMPENSATE for that lack of dark Fur to protect them from the Sun!
Also, people with Melaninated Skin have advanced Skin REPAIR capabilities to keep their skin healthy. That is why Black people show signs of aging much later in life than Albino people. The following study CONFIRMS these facts.
The pigment of the skin protects the body from the sun’s dangerous UV rays, but researchers have not until recently known how this works. Now they report that skin pigment converts the UV radiation into heat through a rapid chemical reaction that shoots protons from the molecules of the pigment.
Researchers at Lund University in Sweden and other institutions have worked out how the pigment of the skin manages to protect the body from the sun's dangerous UV rays. The skin pigment converts the UV radiation into heat through a rapid chemical reaction that shoots protons from the molecules of the pigment. In a new study, the team from Lund University, working with colleagues in France and Italy, have studied pigment in the skin and its building blocks. Pigment in both skin and hair comprises two different types of melanin: eumelanin and pheomelanin. Eumelanin makes us develop a suntan and gives colour to brown and black hair, whereas those with red hair and pale skin instead have high levels of pheomelanin.
"We found that eumelanin converts harmful UV radiation into heat with almost 100 per cent efficiency. The chemical reaction is incredibly quick, taking less that a thousandth of a billionth of a second," said Villy Sundström, Professor of Chemistry at Lund University. What happens in detail in the chemical reaction is that a hydrogen ion -- a proton -- is ejected from the pigment at the same moment the UV light reaches the pigment molecule. The chain of events could be likened to the melanin getting rid of the energy of the UV light by very quickly shooting a proton projectile. This projectile in turn gives off energy to the surrounding membrane tissue in the form of heat. It has therefore converted dangerous UV energy into harmless heat.
"In this way, the pigment disarms the energy in the UV light and prevents it causing harmful chemical reactions," said Villy Sundström. Eumelanin is considered to be the pigment that protects against UV radiation while pheomelanin is believed to cause skin cancer in some way, which explains why people with red hair are more likely to develop malignant melanoma. However, researchers have not previously been aware of what chemical reactions UV light causes in the pigment. There has therefore also been a lack of knowledge of the pigment processes that lead to protection against or development of cancer. "By understanding how the body naturally protects itself against UV light, we can develop better sun protection products based on the same principles. This would provide better protection against skin cancer," said Villy Sundström.
The “Super Protective” properties of Melanin, is probably what has allowed the totally Black Crow and Raven, whose feathers are loaded with Melanin, to develop as the Animal Kingdoms most intelligent creatures.
When it comes to intelligence, Crows should probably be at the top of the list, or close to it. Many scientists think that corvids - the family of birds that includes crows, ravens, rooks and jays - just may be among the most intelligent animals on earth. This intelligent rating is based on their ability to solve problems, make tools as well as consider both future events and other individuals' states of mind. In addition to Crows making customize tools, they understand causality, can reason, count up to five and remember human faces. In Israel, Wild Hooded Crows actually use bread crumbs to catch fish. In Norway and Sweden they have been seen dragging fishing lines out of water to get the hooked fish. They are second only to humans in intelligence — even smarter than apes in some research tests. And what’s also impressive is that their brain-to-body weight ratio is equal to that of the great apes and cetaceans (whales, dolphins, porpoises) and just slightly lower than in humans.