The problem is the wider we cast the net in terms of subject matter for the article, the more room there is for disagreement and debate.  Energies are dispersed, and the article becomes lopsided and uneven.  Read the article on Human skin color.  This article discusses the various theories about human skin color.  One scenario is that fair skin is the result of spontaneous, random mutation, that, theoretically, there were white-skinned people (the result of genetic mutations) in Africa, but they simply did not survive to produce progeny; that the same mutations occurred when humans migrated north, but because of the climate, those mutants survived to bear and rear offspring.  Another scenario posits that humans initially were pale like simians, but as they began to lose their hair, their skin darkened over time as a climatic accommodation.  And there are other theories, as well.  You want to get into melanin in this article  and the accompanying sturm und drang of agrument, disagreement and, potentially, more edit warring (just look at what's happened here with a far narrower piece)  and for material that eventually will be cut out, anyway?  The "mechanics of melanin"?  This still reads like a phenomenally bad idea.