Philtrum

What it is

The philtrum is a distinct vertical indentation located in the centre of the upper lip. In humans, this groove runs from the base of the nose, known as the nasal septum, down to the raised peak of the lip, called the tubercle. The area is framed by two parallel ridges referred to as philtral columns. While this feature is widespread across therian mammals, it appears only as a vestigial mark in humans and most primates, lacking any current biological purpose.

History and origin

This structure is considered a primitive trait for therian mammals, often appearing alongside a glandular nose pad and slit-like nostrils. Monotremes do not possess a philtrum, likely due to their unique beak-like jaws. In evolutionary terms, the feature was originally functional in many species, serving to channel scents from the nose to internal organs. As higher primates relied more on vision than smell, the structure lost its utility, remaining only as a physical remnant in modern humans.

What it means

Various cultures have attached spiritual significance to this facial mark. Jewish tradition suggests an angel taps the unborn child’s lip to seal away heavenly secrets, creating the groove. Similar myths appear in films like Key Largo and Mr Nobody, where an angel’s touch causes forgetfulness. Philippine folklore describes enchanted beings without a philtrum, while Icelandic tales attribute convex lips to hidden elves. These stories link the physical trait to silence, memory, and the supernatural.

The science

During human embryonic development, the philtrum forms where the nasomedial and maxillary processes merge. If these tissues fail to fuse completely, a cleft lip may result. Research indicates that variations in the philtrum can signal certain conditions. A shorter-than-average length has been observed in boys with autism spectrum disorders. Additionally, a flattened appearance may be associated with fetal alcohol syndrome or Prader–Willi syndrome, highlighting its role in developmental health markers.

In culture

The philtrum frequently appears in literature and cinema as a symbol of mystery or origin. Victor Hugo described it in Les Misérables as a sign of chastity. Modern media often references the myth of the angelic tap, using the feature to explain human silence or forgotten past lives. These cultural references transform a simple anatomical detail into a narrative device, connecting physical appearance to themes of knowledge, birth, and the unseen world.

Questions people ask about Philtrum

Good reading and sources

• Philtrum on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data