Which body part tends to spend the longest duration in the anagen phase?

The head, specifically the hair on the scalp, tends to spend the longest duration in the anagen phase of the hair growth cycle. The anagen phase is the active growth phase where hair follicles are stimulated to produce hair. For scalp hair, this phase can last several years, typically ranging from 2 to 7 years, and in some cases even longer, allowing the hair to grow significantly in length.

In contrast, hair on other body parts, such as the arms, legs, and face, generally has a shorter anagen phase. This is largely due to biological and evolutionary factors; for instance, body hair typically serves different purposes and thus follows a different growth pattern that does not require as extended a growth period as scalp hair does. As a result, hair on these areas transitions more quickly into the catagen (transitional) and telogen (resting) phases, making them less prominent in comparison to the longer-growing hair found on the head.