Mutated or receptor-mediated skin color

  • Home Genetics January 3, 2014

Studies of a skin color gene across global populations reveal shared origins

Excerpt: “All instances of a gene mutation that contributes to light skin color in Europeans came from the same chromosome of one person who most likely lived at least 10,000 years ago…”

SLC24A5, a Putative Cation Exchanger, Affects Pigmentation in Zebrafish and Humans

Excerpt: “We noted that the G and A alleles of the single nucleotide polymorphism (SNP) rs1426654 encoded alanine or threonine, respectively, at amino acid 111 in the third exon of SLC24A5.”

My comment: The key contributor to the chromosomal rearrangement that led to the skin color difference between Europeans and West Africans that arose 10,000 years ago is one amino acid in the gene SLC24A5. The amino acid substitution is reported as if it were a mutation. However, the human ortholog is highly similar in sequence and functional in zebrafish. If the human ortholog was highly similar in sequence and was functional in a bird species, we could compare chromosomal rearrangements in zebrafish, humans, and birds via conserved molecular mechanisms of nutrient-dependent pheromone-controlled ecological adaptations. For example, see:  Difference in Plumage Color Used in Species Recognition between Incipient Species Is Linked to a Single Amino Acid Substitution in the Melanocortin-1 Receptor and Estrogen receptor α polymorphism in a species with alternative behavioral phenotypes. However, few people seem to think in terms of conserved molecular mechanisms in species from microbes to man that link single amino acid substitutions to cell types and chromosomal rearrangements in individuals of different species. Instead, mutation-driven evolution seems to be what people think occurs in different species via mutations that result in color differences in fish, birds, and humans.

The fact that the mutated or receptor-mediated skin color differences in humans appear to have rapidly arisen as a result one fixed mutation ~50,000 years ago,  that required another another mutation to fix the change in the genome about 10,000 years ago, attests to the ridiculous power attributed to mutation-driven evolution, which requires two fixed mutations, without explaining how the lighter mutated skin color was naturally selected.  For comparison to the ridiculous lack of theoretical explanatory power, increased vitamin D in the diet seems likely to explain the change as does the need to produce more vitamin D via the change to nutrient-dependent pheromone-controlled receptor-mediated skin color.


Author: James Kohl

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