Final answer:
Hair color is determined by the presence of melanin in hair follicles. More eumelanin results in darker hair while less eumelanin leads to lighter hair. The average number of hairs per square inch on the scalp is approximately 2,200 hairs.
Step-by-step explanation:
Hair color is determined by the presence of melanin, a pigment produced by melanocytes in the hair papilla. The type and amount of melanin present in the hair follicles determine the hair color. Generally, more eumelanin results in darker hair while less eumelanin leads to lighter hair.
Hair color can vary within individuals, and it can change over time due to variations in melanin production. Additionally, as a person ages, melanin production decreases, and the hair may turn gray or white.
It's essential to note that the average number of hairs on the head varies among individuals and can range from around 100,000 to 150,000 hairs. However, the average number of hairs per square inch on the scalp is approximately 2,200 hairs.