What is the indent above your upper lip (and below your nose) called?

The subtle vertical groove situated just above your upper lip and directly beneath your nose has a specific name: the philtrum. This indentation, often bordered by two subtle ridges known as philtral columns, is a common facial feature across many mammals. Its name, "philtrum," originates from the Greek word "phíltron," which translates to "love charm" or "to kiss," hinting at ancient associations with attraction and affection.

While the philtrum appears to have no active function in humans, it holds a significant evolutionary history. In many other mammals, such as dogs and cats, this groove is a functional part of their olfactory system, acting as a channel to transport dissolved odorants from their wet nose, or rhinarium, to specialized scent organs. This enhances their sense of smell and helps keep the nose moist. For humans, however, it is largely considered a vestigial trait. The philtrum forms early in embryonic development when different parts of the face fuse together. A failure in this intricate process can sometimes lead to conditions like a cleft lip.

Beyond its biological origins, the philtrum has also found its way into cultural folklore and aesthetic considerations. In some traditions, like certain Jewish beliefs, it is said to be the mark left by an angel who touches a baby's lip before birth, causing them to forget all the wisdom they learned in utero. From an aesthetic perspective, the definition and length of the philtrum can contribute to facial harmony and are sometimes associated with perceptions of youthfulness. Variations in its appearance, such as a flattened or broader philtrum, can also be indicators for certain genetic syndromes or developmental conditions.