This seemingly contradictory situation is explained by the differing responses of hair follicles to dihydrotestosterone (DHT), a hormone derived from testosterone.
The Role of DHT in Hair Growth and Baldness
- Scalp Hair: Hair follicles on the scalp are particularly sensitive to DHT. High levels of DHT cause these follicles to shrink, leading to hair miniaturization and eventually baldness (male pattern baldness). This is why some men experience hair loss on their heads while retaining hair elsewhere.
- Body Hair: In contrast, hair follicles in areas like the beard, chest, and back are less sensitive to DHT, or even stimulated by it. This explains why many bald men have thick beards, hairy chests, or back hair. The differing sensitivity of hair follicles to DHT is genetically determined. [Reference: Hair follicles in areas that are destined to become bald are especially sensitive to DHT – it makes them shrink. Follicles on the sides and back of the head are not affected by DHT. Confusingly, DHT helps growth of the beard and hair on the chest.]
Genetic Factors and Individual Variation
The distribution and density of body hair are heavily influenced by genetics. While DHT plays a significant role, individual genetic predispositions dictate how follicles respond to this hormone. This explains the wide variation in hair patterns among individuals, even those with similar levels of DHT. [Reference: To a large degree, science has proved him right. Baldness is the result of hair follicles reacting to male hormones. However, men with male pattern baldness do...]
Age and Hair Changes
Hair growth patterns can also change with age. While some men may experience increased body hair in certain areas as they age, others may find their body hair thins out. This variation is largely due to fluctuating hormonal levels and individual genetic makeup. [Reference: One explanation, Scientific American has reported, is that as men age, the hair follicles in the nose and ear become more sensitive to...]
In summary, being hairy but bald is not paradoxical. It's a result of the varying sensitivity of different hair follicles to DHT, coupled with individual genetic predispositions and the natural changes in hair growth patterns that occur throughout life.
