Melanin and Vitamin-D have a unique coalition. Vitamin-D is an essential biomolecule for proper bone formation and a functional immune system. Vitamin-D synthesis takes place predominantly in keratinocytes of the upper epidermis layer stratum spinosum, under the influence of a narrow portion of the electromagnetic spectrum emitted from the sun, namely Ultraviolet B radiation (UVB). The secosteroid Vitamin-D3 is synthesized when the direct precursor of cholesterol, 7-dehydrocholesterol, is exposed to UV-B in human skin. Simultaneously, the primary biomolecule of human skin pigmentation, Melanin, gets synthesized to proficiently absorb UVR, to protect sensitive macromolecules (DNA & proteins), from mutagenesis and destruction. Melanin functions as the main UV-absorbing component in humans, since it has a very high refractive Index and a broad absorption spectrum. Melanin is originated via the oxidation and polymerization of the aromatic amino acid tyrosine which happens in specialized organelles called melanosomes within the melanocytes. Furthermore, during the course of human evolution, melanin has evolved to provide protection against high levels of UVR while still permitting cutaneous production of Vitamin D. However, skin colour phenotypes frequently evolved as the result of independent genetic events of population dispersion into different climates of extremely low or high UVB exposure. Meanwhile, human adaptations to different climates have become more cultural than biological. Expeditious migrations, urbanization, and lifestyle factors have resulted in Vitamin-D deficiency. The prevalence and significance of Vitamin-D deficiencies are subjects of intense biological research. According to the prior literature, lack of sun exposure and abandonment of Vitamin-D-rich foods in the diet is the cause of these deficiencies. Against this backdrop, the present review is an attempt to unravel the mechanism of two archaic biomolecules (Melanin and Vitamin-D) in human evolution and health with the help of previous research articles on online databases namely ResearchGate, PubMed, Google Scholar.
