Final answer:
Pheomelanin is indeed the melanin type that contributes to red and blond hair colors. This pigment, along with eumelanin, determines the range of hair colors seen in humans, and changes in their levels can cause hair to alter color over a person's lifetime.
Step-by-step explanation:
It is true that pheomelanin is the melanin that gives blond and red colors to the hair. Hair color is determined by the presence and ratios of two types of melanin: eumelanin and pheomelanin.
Pheomelanin provides a range of colors from red to yellow, depending on its concentration, which is why it's associated with giving hair blond and red hues. Conversely, eumelanin is responsible for darker hair colors from brown to black.
Over time, the levels of melanin can vary, which may lead to changes in hair color. Additionally, as a person ages, the production of melanin decreases, leading hair to lose its color and become gray or white.
Factors such as genetics and exposure to ultraviolet rays can influence melanin production. For instance, UV exposure can stimulate melanocytes, increasing melanin in the skin and resulting in a tan. This adaptation is a defense mechanism to protect our skin cells from UV damage.