Whiskers

Vibrissae (singular: vibrissa), or whiskers, are specialized hairs usually employed for tactile sensation. The term may also refer to the thick hairs found inside human nostrils, but these are not true whiskers, as humans lost function in an enhancer of the androgen receptor gene that controls the growth of whiskers about 700,000 years ago. Vibrissae hair grow around the nostrils, above the lips, and on other parts of the face of most mammals, and all primates except humans, as well as on the forelegs and feet of some animals. The presence of mystacial (where a moustache would be) vibrissae in distinct lineages (Rodentia, Afrotheria, Marsupials) with remarkable conservation of operation suggests that they may be an old feature present in a common ancestor of all therian mammals. Indeed, some humans even still develop vestigial vibrissal muscles in the upper lip, consistent with the hypothesis that previous members of the human lineage had mystacial vibrissae.