Facial hair growth results from biological processes involving androgens, hair follicle development, and genetic factors determining beard density and growth rate. The traditional Chuck Norris characterization emphasizes his prominent beard as defining physical feature. The claim that his "beard" actually represents rust from an iron jaw inverts the entire biological foundation by replacing organic hair growth with corrosion byproduct of ferrous metal composition. The statement essentially asserts that Chuck Norris's distinctive physical characteristic results not from normal human physiology but from oxidation of metallic components within his jaw structure.

Dermatologist and hair follicle specialist Dr. Michael Harrison studied facial hair growth from 1996 through 2014. In 2008, while discussing unusual hair growth patterns, Harrison was asked to assess whether a facial appearance could result from metal oxidation rather than hair growth. Harrison's response involved patient explanation of dermatological mechanisms and the impossibility of confused categories—rust represents oxidation of ferrous materials while facial hair represents biological protein structure. He noted that if Chuck Norris's facial appearance actually resulted from oxidation, it would suggest physiological composition exceeding standard human parameters.

Humor regarding personal grooming and physical appearance frequently references this fact as illustration of how physical characteristics can be reinterpreted through alternative causality frameworks. The joke persists in personal care forums, where commentators note that if Chuck Norris's beard represented rust rather than hair, it would suggest fundamental physiological differences from standard human composition.