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Post by djoser-xyyman on Nov 7, 2013 20:00:48 GMT -5
Look man. Stop posting outdated papers. Did you read the ******2013****** Shriver paper? OP.
And you still don't understand how pigmentation works, do you?
Your SLC45A2 world has come to an end in 2013......Don't get it..huh?
First read the paper then get back to me. I will give you a few days. If you don't find it...I will show it to you. I will put up.....
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Post by zarahan on Nov 8, 2013 3:39:00 GMT -5
SOme quotes:
"Our results indicate that Cape Verdean pigmentary variation is the result of variation in a different set of genes from those determining variation within Europe, suggest that long-range regulatory effects help to explain the relationship between skin and eye color, and highlight the potential and the pitfalls of using allele distribution patterns and signatures of selection as indicators of phenotypic differences..
The strong effect of genomic ancestry on skin color is also striking in the context of eye color; there is only a weak correlation between skin and eye color in Cape Verdeans (R‘2 =0.14), and African genomic ancestry is also weakly correlated (R‘2 = 0.08) with eye color (Figure 1c, 1d). Overall, these observations point to different genetic architectures for skin and eye color...
These results suggest that an APBA2 (OCA2) mutation conferring light skin arose BEFORE the spread of humans out of Africa, and that a HERC2 (OCA2) mutation conferring pale eye color arose much later."
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Good roundup. So:
a) are they saying that what causes skin color variation in peoples of African descent is different from what causes skin color variation among Europeans?
(b) Apparent "race mixes" are not necessary to explain why some Africans may have lighter skin or eyes?
(c) Could the above explain the phenomenon of the paler-skinned so-called 'Red Igbo" in West Africa?
d) When they say: "These results suggest that an APBA2 (OCA2) mutation conferring light skin arose BEFORE the spread of humans out of Africa, and that a HERC2 (OCA2) mutation conferring pale eye color arose much later."
^^COuld this not mean a paler or lighter shade, as in many European Mediterranean populations but not the heavy depigmentation found in the colder, more northern climes of Europe or Asia? COuld not this heavier depigmentation have arisen later?
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Post by djoser-xyyman on Nov 8, 2013 20:14:52 GMT -5
^ Seems like only Truthteacher is catching on... Exactly how are we defining white any way? Of course West Africans are not WHITE.
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Post by djoser-xyyman on Nov 8, 2013 20:24:42 GMT -5
@ my man.. I don't want to overwhelm you but you got me all excited, You have me chumping at the bits, I thought you were someone who was knowledgeable as me or at least formidable. Anyways - here is a teaser. I am disappointed we can't even get past the light skin dilemma. But the blue eye thing is even more challenging. But sadly you don't even understand the light skin genotype. Anyway here is something for the lurkers or newbies. You may benefit from it also. Your job now is to do your research and find the study. The author is well known and it is from a 2012 study ..not a hypothesis from more than a decade old study by obsolete Jablonski(2000) or something 5 yo. Also it is authored by a major player on skin, eye and hair pigmentation. There is even a disease named after him. I hope you will get off that SLC45A2 wagon and learn something from what I posted. That belief held by simplistic racialist is so ...old....SLC45A2 is NOT European and never will be. Only in the delusional simplistic mind of a racialist it is. I hope some of you understand the point being made. There are several candidate genes for blue eyes also. HERC2 is one along with others. Reading only ONE paper does not make you an expert.
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Post by djoser-xyyman on Nov 8, 2013 20:25:13 GMT -5
QUOTE FROM THE STUDY: Notably, skin color has only been a target for natural selection in hominids following the development of hairlessness [7], and a genetic change allowing melanocytes to reside in the epidermis must therefore have occurred early during our evolution.
DJOSER: I TOLD LIONESS OVER AT ES ABOUT 2 YEARS AGO THAT LIGHT SKIN WAS ANCESTRAL AND HE DID NOT GET IT. I HOPE YOU ARE MORE FORMIDABLE THAN HIM AND GET IT. HE GAFAWWED AT THE REMARK.
We now know of a large number of genes that impact on human pigmentation, especially in the melanosome biogenesis or the melanin biosynthetic pathways [1], and we are now in a position to characterize the genetic variation underlying the diversity seen in these pigmentation traits that has arisen during hominid evolution
OCA2 (Ch15q11.2) The OCA2 gene, homologous to the mouse pink-eye dilute locus, is located on chromosome 15 and downstream of the HERC locus. The regulation of its expression has been proposed to exert the strongest influence on iris color [3], as well as having associations with skin and hair color [46] in European-derived populations. The OCA2 protein is thought to be a mature melanosomal membrane protein [63], with a potential role in trafficking other proteins to melanosomes [64]. The key determinant SNP rs12913832*T/C for the regulation of OCA2 expression is located in a short
DJOSER: THERE ARE DIFFERENT PATHWAYS OR "INGREDIENTS" THAT LEAD TO THE "SYNTHESIS" OF OCA2 WHICH IN TURN PRODUCES MELANIN. BLOCKING ANY OF THE PATHWAYS(PIGMENTATION GENES) /OR INGREDIENTS LEAD TO LIGHT SKIN.
**OCA2 IN ASIA** [72], and a later study of 24 populations showed the highest frequency was 0.52 in the Oroquen population in China [73]. These reports provide evidence for lighter skin pigmentation evolving by means of selection acting at least partly genetically independently in Europeans and East Asians, that is, convergent evolution. However, in Europeans selection may have been predominantly for lighter eye color.
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Post by djoser-xyyman on Nov 8, 2013 20:26:21 GMT -5
TYRP1 (Ch9p23) and DCT (Ch13q32) While TYR catalyses the key initial step in melanin production, TYRP1 and DCT (TYRP2) act at subsequent steps, influencing the quantity and the quality of melanins and stabilizing the TYR enzyme. They also have some function in melanocyte survival after ultraviolet radiation (UVR) stress and in the maintenance of melanosomal structures. The TYRP gene family evolved by recurrent gene duplication from a common ancestral TYR early in evolution giving rise to TYRP1 and DCT [80]. In humans, mutations of TYRP1 causing OCA3 are frequently observed in South Africa [13]. Part of this phenotype is red bronze skin, ginger-red hair and blue irides. In a surprising finding, it was recently reported that a nonsynonymous amino acid change, Arg93Cys, in the TYRP1 protein is a major determinant of the blonde hair phenotype. This allele has a frequency of 0.26 on the Solomon Islands and is not seen outside of Oceania, so it
DJOSER: INDIGENOUS SOUTH AFRICANS HAVE A HIGHER FREQUENCY OF BLUES EYES AND REDDISH HAIR THAN TROPICAL AFRICANS. NO ADMIXRURE NEEDED. BEING FAMILIAR WITH THE CARIBBEAN PEOPLES. I HAVE SEEN THIS PHENOMENON IN THE ISLANDERS. ONE PAPER I READ SAID IT OCCURS IN 1-600 WEST AFRICANS.
(Box 1). In the European population TYRP1 rs1408799*A has been associated with blue eye color [24,25], though other SNPs are also associated with blue eyes [49,83], so the causative SNP is yet to be recognized..
DJOSER: DO YOU KNOW WHY THIS PHENOTYPES(EG BLUE EYES) IS FOUND SO FREQUENTLY IN SOUTH AFRICA AND THE SOLOMON ISLANDS??? IF YOU SUGGEST ANYTHING ABOUT ADMIXTURE THE EDUCATION STOPS HERE!!!. TIC! TOC!
SLC24A5 (Ch15q21.1) Lamason and coworkers [89] reported that a mutation in Quillen and coworkers [47] estimate the effect of rs1426654*C/T on melanin index, via admixture mapping, to be of the same magnitude as the SLC45A2 rs1426654*A/374Phe change, and their data seem consistent with an ****additive****, rather than a dominant, allelic effect of the SLC24A5 rs1426654*A/111Ala allele on skin reflectance. Interestingly, in the indigenous American populations they studied, the rs1426654*A/111Ala allele is at intermediate frequencies, and shows no evidence of selection [47], while there is strong evidence for selection in Europeans. Mouse Slc24a5 null animals have normal
Apart from protecting against the damaging effects of solar UVR, melanin has several other roles in the body, including scavenging reactive oxygen species, protecting nutrients from photodamage and possibly modulating the inflammatory response. Melanin can also provide camouflage, transport energy and bind drugs, and is involved in hearing, sight and regulation of body heat [103].
DJOSER: THERE IS THAT "ADDITIVE": WORD AGAIN. NOTE: MELANIN MAKES YOU SEE WELL, MELANIN MAKES YOU KEEP WARM, MELANIN MAKE S YOU ENERGETIC, MELANIN LOWERS THE RISK OF CANCER, MELANIN AIDS NUTRIENT UPTAKE, MELANIN MAKES YOU HEAR BETTER, MELANIN IS A CURE FOR PSYCHOTIC DISEASES EG DEPRESSION AND SUICIDAL TENDENCIES, MANIC DEPRESSION AND VIOLENT OUTBURST. MELANIN MAKES THE BODY HEAL FASTER. DID I LEAVE ANYTHING OUT? MALANIN MAKES OR MADE US HUMAN?
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Post by djoser-xyyman on Nov 8, 2013 20:26:48 GMT -5
Perhaps more surprisingly, pigmentation genes were NOT associated with blood folate concentrations in a GWAS [123], consistent with earlier clinical studies of UVA exposure effects on folate levels [124]. However, the behavior of melanin pigment itself after UVR exposure in undergoing the immediate pigment darkening response may participate in protection against folate photodegradation [125]. Darkly pigmented skin does display more rapid barrier recovery after acute damage than lightly pigmented skin types [127]. Thus, these authors have proposed that pigmentation in hominids evolved in response to the combined stress of UVR exposure and low humidity. Moreover, there is an intimate link between maintaining the permeability barrier of the skin and antimicrobial defenses, and some researchers suggest that darkly pigmented melanocytes enhance this defense by acidifying the outer epidermis [126,127].
DJOSER:MAN! I WISH I WAS WHITE AND HAD BLUE EYES.
DJOSER: I CAN POST ON ABOUT TWO DOZEN PAPERS...BUT YOU GET THE POINT?! AS I TOLD THOSE GUYS OVER AT ES. WHEN I POST GET OUT A PEN AND NOTEPAD.
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Post by djoser-xyyman on Nov 8, 2013 20:54:11 GMT -5
Of course West Africans are not white. Key words here is additive, selective sweep, etc. Main point here is AMH skin shade is perfectly adjusted to their geographic latitude. The genes necessary to adjust the skin pigmantation shade was present BEFORE AMH left Africa including the falsely beloved SLC45A2. If the man understood what he read he will realize that SLC24A5 has a greater impact on skin pigmentation than SLC45A2. Of course no admixture is needed. Not to say some aren't admixed. And yes heavier depigmentation occured as AMH moved North... AND South. The mechanism may be slightly different. But the foundation was layed in Africa. In fact it never "left". per Rees et al. Light skin is ancestral to dark skin. But homins had dark fur to protect them. But if you follow the previous study/post, it is because dark skin we became human. SOme quotes: "Our results indicate that Cape Verdean pigmentary variation is the result of variation in a different set of genes from those determining variation within Europe, suggest that long-range regulatory effects help to explain the relationship between skin and eye color, and highlight the potential and the pitfalls of using allele distribution patterns and signatures of selection as indicators of phenotypic differences..
The strong effect of genomic ancestry on skin color is also striking in the context of eye color; there is only a weak correlation between skin and eye color in Cape Verdeans (R‘2 =0.14), and African genomic ancestry is also weakly correlated (R‘2 = 0.08) with eye color (Figure 1c, 1d). Overall, these observations point to different genetic architectures for skin and eye color...
These results suggest that an APBA2 (OCA2) mutation conferring light skin arose BEFORE the spread of humans out of Africa, and that a HERC2 (OCA2) mutation conferring pale eye color arose much later." ------------------------- Good roundup. So: a) are they saying that what causes skin color variation in peoples of African descent is different from what causes skin color variation among Europeans? (b) Apparent "race mixes" are not necessary to explain why some Africans may have lighter skin or eyes? (c) Could the above explain the phenomenon of the paler-skinned so-called 'Red Igbo" in West Africa? d) When they say: "These results suggest that an APBA2 (OCA2) mutation conferring light skin arose BEFORE the spread of humans out of Africa, and that a HERC2 (OCA2) mutation conferring pale eye color arose much later." ^^COuld this not mean a paler or lighter shade, as in many European Mediterranean populations but not the heavy depigmentation found in the colder, more northern climes of Europe or Asia? COuld not this heavier depigmentation have arisen later?
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Post by herodotus on Nov 9, 2013 10:08:42 GMT -5
Derived SLC24A2 is not African.
It only appears along the coasts by recent gene flow. It is completely absent from Sub-Saharan Africa and even northern mainland North Africa.
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Post by herodotus on Nov 9, 2013 10:27:28 GMT -5
The divide between south + northern Europeans in skin pigmentation is greatly exaggerated through tanning. Under the arm, or from a non-exposed part of the body, there is a very minute difference. Southern Europeans only appear darker through aquiring tans.
Compare Basques to South English, North English, Welsh, Irish and Germans via a skin reflectance spectrophotometer (taken under arm) -
Germany (Mainz) 66•90 Ireland (Ballinlough) 65•20 Ireland (Carnew) 64•50 Ireland (Longford) 65•00 Spain (Basques) 65•70 United Kingdom (London) 62•30 United Kingdom (Northern) 66•10 United Kingdom (Wales) 65•00
(higher numbers = lighter skin)
- Jablonski, N. G., Chaplin, G. (2000). “The evolution of human skin coloration”. Journal of Human Evolution. 39(1). pp. 57-106.
Basques even turn out to be slightly lighter skinned than Welsh, Irish and southern English. The differences are only very small (1-4).
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Post by djoser-xyyman on Nov 9, 2013 14:56:53 GMT -5
If I were you I would shut up.
Knife to a gun fight...Ha! Ha!
Oh now you are agreeing with me. SLC45A2 is meaningless? Time you come around. "Say uncle" before we talk other genes eg SLC24A5. I have a lot to teach you.
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Post by anastasiaescrava on Nov 10, 2013 20:19:10 GMT -5
I'm listening.
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Post by truthteacher2007 on Nov 10, 2013 22:32:35 GMT -5
^ Seems like only Truthteacher is catching on... Exactly how are we defining white any way? Of course West Africans are not WHITE. I know that. But when we say white, exactly what do we mean? White like who exactly? How light does one have to be to be considered "white" skinned?
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Post by herodotus on Nov 11, 2013 4:10:38 GMT -5
^ Seems like only Truthteacher is catching on... Of course West Africans are not WHITE. I know that. But when we say white, exactly what do we mean? White like who exactly? How light does one have to be to be considered "white" skinned? Light skin is 1 - 14 on the Luschan Scale. Dark skin is 24 - 36. Between these extremes are light/medium brown shades. There are no Africans with 1 - 14, this range falls outside African diversity.
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Post by djoser-xyyman on Nov 11, 2013 19:46:51 GMT -5
continuing...
This is hot offf the press. Published Nov2013.
I was going to hold this one back but...Talk about Karma...
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The Light Skin Allele of SLC24A5 in South Asians and Europeans Shares Identity by Descent - Richard Villems1,2,10, Toomas Kivisild Nov 2013
A total of 378 candidate loci, including 171 cloned genes, are currently recorded in the Color Genes database (http://www.espcr.org/ micemut/), yet only a few of them have been confirmed to have potentially function-altering polymorphisms in humans.
One of the key pigmentation genes in humans is SLC24A5 (OMIM 609802). It is located on chromosome 15q21.1 and encodes a protein called NCKX5. The association of this gene with lighter pigmentation SNP ID: rs1426654) in the third exon of this gene explains 25–38% of the skin color variation between Europeans and West Africans. The ancestral (G) allele of the SNP predominates in African and East Asian populations (93–100%), whereas the derived (A) allele is almost fixed in Europe (98.7–100%) [4]. Functional assays of this gene suggested its direct involvement in human melanogenesis through cation-exchange activity [17], [18]. However, the fact that the ancestral (G) allele is virtually fixed not only in Africans but also in East Asians suggests that light skin at high latitudes evolved independently in East and West Eurasia [19].
Results
Variation of melanin index in South Asia and its association with rs1426654 SNP Comparison with published datasets for the regions of the world revealed that the observed range in South Asians was three times greater than that in East Asians and Europeans and comparable to that of Southeast Asians (Table 1). Notably, the Onge and the Great Andamanese populations of Andaman Islands also showed absence of the derived-A allele
The isofrequency map illustrates high frequencies of the rs1426654-A allele in Europe, Middle East, Pakistan, moderate to high frequencies in Northwest and Central Asia, while being almost absent in East Asians and Africans with NOTABLE EXCEPTIONS in Bantu (Southwest), San, Mandeka, and Ethiopians (Table S7, Figure 2). As rs1426654-A allele frequency was found to be higher in West Eurasian populations that are known to share
Fine-scale genetic variation of SLC24A5 A total of 60 variable sites (including 23 singletons), one insertion, and one tetranucleotide repeat were identified WITH DERIVED ALLELE FREQUENCIES ranging from 0.005 to 0.39. Results of the resequencing study for these variable sites are presented in Table S9. According to dbSNP (http://www.ncbi. nlm.nih.gov/projects/SNP/) build 137 (June 2012), 21 of these 62 identified variants were novel. The insertion present in the 59 flanking region (position 48411803) was confined to two San individuals (San 15 and San 17). Comparison of polymorphic sites across different regions revealed that the exons of SLC24A5 are highly conserved in humans. We detected only two variable positions within exons, with rs1426654 being the only nonsynonymous SNP. The other variant, a synonymous (Ser-Ser) mutation identified at exon 7 at position 48431227, was shared by FOUR AFRICANS. POPULATIONS
from regions previously reported to exhibit a high frequency of the rs1426654-A allele (North Africa and Middle East, Central Asia, SOUTH ASIA AND EUROPE; see Figure 2) show low levels of intra- and inter-population diversity in the resequenced region (Figure 4,
Table S11
The schematic tree representing the 8 most common haplogroups is shown in Figure S3. Haplogroup G was the most common and geographically widely spread clade, being found in 7 of the 8 geographical groups examined. Haplogroup C was confined to sub-Saharan Africans only, while the rest of the observed haplogroups were shared between African and non- African populations. We conclude that all of the 73 phased chromosomes (from Europe, sub-Saharan Africa, Middle East, South Asia, North and Central Asia) with the rs1426654-A allele form a monophyletic group because they share the same haplotype background regardless of their geographic origin. In other words,all carriers of the mutation in our global sample share it by descent. THE PRESENCE OF THE DERIVED A ALLELE IN SUB-SAHARAN AFRICA, ALTHOUGH IN LOW FREQUENCIES (2/73 - ONE HETEROZYGOUS MANDEKA AND ONE HETEROZYGOUS SAN INDIVIDUAL) (FIGURE S3) IS CONSISTENT WITH EARLIER FINDINGS [32].
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