Final answer:
The distribution of skin tones globally is influenced by ancestral exposure to UV radiation, with darker skin near the equator and lighter skin towards the poles, reflecting an evolutionary adaptation to sunlight. The concept of race based on skin color is biologically inaccurate, as human traits vary along a spectrum. Cultural perceptions of skin color have also influenced modern conceptions of race.
Step-by-step explanation:
The general geographic distributions of darker and lighter skin tones are primarily influenced by the levels of ultraviolet radiation that people's ancestors were exposed to in various parts of the world. As one travels from the equator towards the poles, there is a noticeable shift in skin pigmentation among indigenous populations. This gradation sees deep brown skin tones in equatorial regions, like Kinshasa, shifting to lighter shades as you move towards northern latitudes, such as Tromsø in Norway. This gradual change in skin color from darker to lighter is due to evolutionary adaptations that balanced the need for protection against the sun's harmful UV radiation in sunny climates with the requirement for vitamin D synthesis in areas with less intense sunlight.
Biological anthropology indicates that the concept of discrete racial categories based on skin color and other traits is flawed. Instead, human traits vary along a spectrum without distinct boundaries, which has resulted in an immense diversity of appearances across human populations. The traditional view aligns darker skin with sun-rich environments near the equator to protect against UV radiation, while lighter skin is favored in sun-deprived areas like northern Europe to facilitate vitamin D production. Cultural perceptions of skin color and socioeconomic status have further shaped modern conceptions of race, often diverging from biological qualities.