Final answer:
Melanin is the pigment responsible for the natural coloring of hair, and it comes in two forms: eumelanin for dark hair and pheomelanin for red hair. As individuals age, melanin production decreases, leading to gray or white hair.
Step-by-step explanation:
The pigment that provides the natural coloring for a person's hair is melanin. Hair color is determined by the pigmentation of hair follicles due to two types of melanin: eumelanin, which contributes to black and brown colors, and pheomelanin, which gives a red color. The production of melanin is genetically determined and can vary over time, causing a person's hair color to change. In addition, exposure to UV rays can stimulate the production of melanin, leading to a darkening of the skin or a tan, while also providing protection against UV radiation. However, overproduction of melanin can impact vitamin D creation. As people age, melanin production decreases, which often results in gray or white hair.