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[QUOTE]Originally posted by MindoverMatter718: [QB] Of extreme importance is the fact that original Island Melanesian samples showed relatively higher frequency levels than that of CEPH Island Melanesian populations. [QUOTE]Originally posted by The Explorer: [i]The discordance between our Fst-based divergence values and allele frequencies in the Melanesian CEPH populations at ASIP largely stem from the relatively [b]low frequency of the ancestral allele[/b] in the [b]2 CEPH Island Melanesian populations[/b] relative to our [b]original Island Melanesian sample[/b]. These discrepancies make it difficult to determine if ASIP truly underlies broad pigmentation differences between darkly and lightly pigmented populations or instead inter-population variation at this locus can largely be explained by differences between Africans and non-Africans. The discordance between the [b]frequencies of the ASIP ancestral allele[/b] in our original Island Melanesian sample and the Melanesian samples from the CEPH panel may be indicative of both the complex demographic history of Island Melanesia (involving several migratory events (Spriggs 1997) and probable extensive genetic drift (Friendlaender 1975, 1987) as well as the importance of multiple loci in determining pigmentation phenotype[/i] - Norton, Kittles et al. Note that the sample of the "original Island Melanesians" showed up relatively greater frequencies of the ancestral state of the allele in question than the "CEPH Island Melanesians". Whether the derived state has much of a "lightening" effect amongst sections of Melanesians or not, is trivial to the point that the ancestral state is predominantly found in equatorial Africans. [/QB][/QUOTE]Also, is that Khoisan seem to possess high frequencies of the allele in a derived state. [QUOTE]Originally posted by The Explorer: [QUOTE]And indeed, they'd have to have ancestral alleles, because after all, that is what's keeping them "dark complexioned". In the meantime,... [i]The [b]lightly pigmented[/b] hunter-gatherer San populations of Southern Africa is exceptional in having a [b]high frequency[/b] of the [b]derived allele[/b] relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area.[/i] - Norton et al. Note that while it is said that the allele in question is suggestive of not being a new one, it is recognized as being in the "derived" state. [/QUOTE][/QB][/QUOTE]and of course the fact that every study on pigmentation confirms that darkskin is the ancestral state in humans, and lightskin in East Asians and Europeans are not only independent of eachother, but are also of recent origin..... Dark skin evolved with the loss of 'fur' in hominids and is the original state of all homo sapiens. - Jablonski. [2000] The original human population would have been [b]very dark[/b] , similar to, today's equatorial Africans. - Jablonski [2006] [QUOTE] Signatures of Positive Selection in Genes Associated with Human Skin Pigmentation as Revealed from Analyses of Single Nucleotide Polymorphisms http://www3.interscience.wiley.com/journal/120118254/abstract ABSTRACT Phenotypic variation between human populations in skin pigmentation correlates with latitude at the continental level. A large number of hypotheses involving genetic adaptation have been proposed to explain human variation in skin colour, but only limited genetic evidence for positive selection has been presented. To shed light on the evolutionary genetic history of human variation in skin colour we inspected 118 genes associated with skin pigmentation in the Perlegen dataset, studying single nucleotide polymorphisms (SNPs), and analyzed 55 genes in detail. We identified eight genes that are associated with the melanin pathway (SLC45A2, OCA2, TYRP1, DCT, KITLG, EGFR, DRD2 and PPARD) and presented significant differences in genetic variation between Europeans, Africans and Asians. In six of these genes we detected, by means of the EHH test, variability patterns that are compatible with the hypothesis of local positive selection in Europeans (OCA2, TYRP1 and KITLG) and in Asians (OCA2, DCT, KITLG, EGFR and DRD2), whereas signals were scarce in Africans (DCT, EGFR and DRD2). Furthermore, a statistically significant correlation between genotypic variation in four pigmentation candidate genes and phenotypic variation of skin colour in 51 worldwide human populations was revealed. [b]Overall, our data also suggest that light skin colour is the derived state and is of independent origin in Europeans and Asians, whereas **dark skin** color seems of unique origin, **reflecting the ancestral state in humans**.[/b] [/QUOTE] [/QB][/QUOTE]
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