Introduction
Human skin color varies from dark brown to light colors. Differences in skin color between individuals are caused by variations in pigmentation resulting from genetic inheritance from biological parents, sun exposure, or a combination of both. In addition, distinctions between populations result from natural selection due to environmental differences and the control of the biochemical outcomes of ultraviolet radiation that penetrates the skin. Thus, it is essential to establish basic information about human skin color.
Skin Color as a Geographical Adaptation
It is essential to note that skin color is a significant adaptation to living in a particular latitude and varies significantly. For example, among Africans, one can find people with relatively light skin and those who are completely black (LaBerge et al., 2020). Moreover, the intensity of pigmentation correlates with the power of ultraviolet radiation, which is typical for that region. It reaches its maximum at the equator and its minimum at high latitudes, where the lightest-skinned people live (LaBerge et al., 2020). While dark skin protects its wearer from excess ultraviolet light, white skin is an adaptation to the lack of it since some ultraviolet light is required for the synthesis of vitamin D.
The Role of Melanin in Skin Pigmentation
Melanin is an organic substance produced by the oxidation of the amino acid tyrosine. Melanins are found in a variety of living organisms and can perform various functions. For instance, the black ink spray produced by cuttlefish also contains melanin. Skin color depends on the number of melanosomes, size, melanin saturation, and distribution in the skin. In dark-skinned people, melanosomes are large, melanized, and do not form clusters (LaBerge et al., 2020).
Individuals with fair skin have smaller melanosomes that often cluster, surrounded by a membrane. Furthermore, melanin synthesis is determined by multiple genes, hormonally regulated, and influenced by age and the intensity of ultraviolet light. Under its influence, melanocytes become more active, synthesizing melanin, and tanning occurs (LaBerge et al., 2020). That is why anthropologists determine a person’s innate skin color in the places least exposed to the sun’s rays, in other words, on the inner side of the hand.
Genetic and Environmental Influences on Skin Tone
There is still an incomplete understanding of the genetic mechanisms underlying human skin color variations. However, genetic studies have discovered several genes that influence human skin color in specific populations, demonstrating that this occurs independently of other physical characteristics, such as eye and hair color (LaBerge et al., 2020). Different populations have distinct allele frequencies of these genes, and the combination of these allele variations results in complex, continuous changes in skin coloration. This can be observed in modern humans today (LaBerge et al., 2020). Studies of populations and admixture suggest a three-way model for the evolution of human skin color: dark skin developed in early hominids in sub-Saharan Africa, and light skin developed independently in Europe and East Asia after modern humans emerged from Africa.
Conclusion
Therefore, skin color is determined by a substance called melanin. The more melanin in a person’s skin, the darker it appears. When white-skinned people spend a considerable amount of time in the sun, a lot of melanin forms in their skin; in other words, they tan. The dimmer light of the European sun contains much less ultraviolet light than the sunlight in Africa. Thus, one can explain that Europeans have a brighter skin than the Negro race.
Reference
LaBerge, G. S., Duvall, E., Grasmick, Z., Haedicke, K., Galan, A., Leverett, J., & Pawelek, J. (2020). Focus: Skin: Recent advances in studies of skin color and skin cancer. The Yale Journal of Biology and Medicine, 93(1), 69.