[Paranasal sinuses: only one of nature's games?]

Many theories exist concerning the function of paranasal sinuses, but it is rather difficult to definitively name the right one. Despite the fact that many of them have been proved to be wrong, they are still used.

Galen postulated 2000 years ago that they were "porous bones", which helped with weight reduction. Like Galen's theory, most of the others have been refuted as well. A list of these refuted theories covers a range of postulated functions including a relative warming or moistening of the breath, protection against high pressure in the nasal region when sneezing, paranasal sinuses as a place of efficient mucus production, or an aid for smelling, similar to the ethmoidal cells of the porcupine. Others include an isolated function for protection against cold climates and an aid for formulating sound by acting as a resonance chambers.

Two theories still remain. One says that the paranasal sinuses are only the result of the evolutionary processes that have taken place in the skull during human development. The other theory explain that the form of the paranasal sinuses exists through the influence of the forces created during the act of chewing. Small cavities appear as a result of the minimal energy created, and these cavities can be found in the form of paranasal sinuses.