Why does one eyebrow hair grow faster than others in old men?

Normal aging change: It is normal in men for the hair of the eyebrows, ears, and nose to become longer and coarser with age. It is likely that there will be more long eyebrow hairs as a person ages. The exact reason for this is not known, but other normal aging changes include graying, hair loss, and thinning of hair. Much of this is genetically determined and not modifiable by diet, etc.