The depressed area of skin under your nose and above your upper lip is called your philtrum.

The philtrum allows humans to express a much larger range of lip motions than would otherwise be possible, which enhances vocal and nonverbal communication. The ancient Greeks believed that the philtrum was one of the most erogenous spots on the human body, hence the etymology. According to the Jewish Talmud (Niddah 30b), God sends an angel to each womb and teaches a baby all the wisdom that can be obtained. Just before the unborn baby comes out, the angel touches it between the upper lip and the nose and all that it has taught the baby is forgotten.

The aquatic ape hypothesis provides a potential explanation for the philtrum. The hooded nose in the human species is seen as an adaptation that is not seen in the apes, preventing water from entering the nasal passage while swimming.