Humanity's survival is highly dependent on a mechanism to manage sunlight and repair damaged DNA. No melanin means no future Sunlight--especially the ultraviolet (UV) part of the light spectrum--is naturally a photocarcinogen. It can penetrate keratinocytes, damage the DNA, and lead some cells to possibly be transformed into cancer cells, such as a deadly melanoma. The cumulative effect on the human species of sun-damaged DNA over time is not trivial. Humanity's survival is highly dependent on a mechanism to manage sunlight and repair damaged DNA. People produce a complex compound called melanin that dissipates the damaging effect of UV light as heat and helps prevent skin cancers in other ways. The transfer of melanosomes from melanocytes to skin cells is unique in human biology, requiring a whole organelle specific to one cell type to be transferred to a completely different type of cell. How? The melanocyte will form long arms that will extend up between the skin cells. Growing inside are microtubules (so small that 3,000 could fit in the diameter of a human hair), which act like railroad tracks to shuttle melanosomes. Tiny protein motors made for the microtubules pull the melanosomes outward. Under the direction of at least two more genes and controlled by four carrier proteins, the melanosome is put into a transfer vesicle at the tip of the arm. This tip fits into a special invaginated spot on a skin cell, and then the melanosome is injected into it. Skin cells will convey melanosomes to the sunward side of their nuclei. As illustrated in human skin, raw energy from the sun must be managed by preexisting complex biological systems or else it kills life.
This fact of nature still reigns over all evolutionary speculations. In 2024 about 200,000 cases of melanoma will be diagnosed in the UUSA alone, with an estimated 5 million reported and unreported new cases of mostly curable basal cell and squamous cell skin cancer--predominantly in lighter-skinned people globally. Melanin certainly provides a measure of natural protection, but nobody is immune from skin cancer, regardless of skin color and all need to be aware of skin care and protections. When people overexpose or fail to protect their skin, or have a defect in the pigment-making process, the sun's UV energy can eventually overwhelm skin's protective and repair mechanisms with deadly results as well as cause infertility and shorter lifespans in Caucasian children according to a recent Norwegian study.