Why do we have sinuses? I know they're little air pockets located behind the forehead, eyes, cheeks, and maybe somewhere else, but what function do they serve? I don't think they are just vestigial organs like the appendix, and clearly they are not an amazing "evolutionary development" like opposable thumbs, so what do they do?
Here, from http://entassociates.com/sinus.htm:
"Sinuses are part of the nasal air and membrane system that produces mucus. Normally, the nose and sinuses produce between a pint and a quart of mucus and secretions per day. This mucus passes into and through the nose, sweeping and washing the membranes, picking up dust particles, bacteria, and other air pollutants along the way. The mucus then flows backward into the throat where it is swallowed, down into the stomach where acids destroy any dangerous bacteria. Most people do not notice this mucus flow because it is just a normal bodily function."Yuck!!??!! On the other hand, if you can remove yourself from thinking just about mucus and bacteria, this is really a quite ingenious design. Just think, we could have some sort of mask over the attractive face or a filter system that obstructed our normal activities to repel dust, bacteria, and other small particles. The runny nose is your sinuses' attempt to flush out the bacteria with extra secretion, just as coughing is the lung's attempt to expel the gunk caught there. In fact, even when the sinuses "malfunction"and hurt because your sinuses have swollen too much and significantly narrowed, or even closed, the drainage openings causing a back-up of mucus. But even when you end up with painful sinusitis, the effect is fatigue and discomfort. Both of which force you to rest and take a break from normal activity. This is quite brilliant. Your body quickly gets the message that something is not right and you must alter your schedule to fix it. Of course, once it's fixed, you feel better and the sinuses go back to being unseen, unheard, and lying peacefully below the surface of our visage. Thank God that He designed the bacteria and dust filter to go under and not over the face.