Final answer:
Dark skin is advantageous in the tropics because it helps protect from overexposure to ultraviolet radiation and prevents the synthesis of excessive amounts of vitamin D.
Step-by-step explanation:
In the tropics, dark skin is advantageous because it helps protect from overexposure to ultraviolet radiation. The pigment melanin, which is more abundant in dark-skinned individuals, absorbs and protects the underlying layers of the skin from the damaging effects of UV radiation from the sun. This protection reduces the risk of skin cancer and other skin damage caused by excessive UV exposure.
Dark skin also prevents the synthesis of excessive amounts of vitamin D, which could be harmful in tropical areas where sunlight is strong. However, it's important to note that individuals with dark skin may need more time in the sun to produce the same amount of vitamin D compared to individuals with lighter skin.
Overall, dark skin in the tropics provides a natural defense mechanism against the harmful effects of UV radiation, while still allowing for the synthesis of essential vitamin D.