 |
Why does the nose have two holes? |
Outside the Body
If you picture an imaginary line running right down the middle of your face, from your forehead to your chin, both sides of that line would be pretty much a mirror image of each other. Each side would have one ear, one eye, one eyebrow, one nostril, half a nose, and half a mouth. Our bodies like to match left and right. But still, why have two nostrils, instead of just one big one right in the center?
Scientists have a pretty good idea of how two nostrils help us. Having two eyes makes us see better. Having two nostrils makes us pick up smells better! Even though our nostrils look the same, they don’t act the same. They take turns swelling and tightening on the inside. That means one airway is smaller than the other, and air travels through that nostril more slowly.
We smell things because particles in the air enter our nose, which has special smell sensors. Not all smells are the same! Some smells are best picked up in big deep breaths. If they travel too slowly the particles may break up before our brains have a chance to understand what they are. Other smells need time for our noses to pick up. If they get lost in a deep breath, we might not be able to sense them at all. By having different speeds of airflow in our nostrils, we can pick up more types of smells than we could with just one nostril.
Know Your Nose
Can you tell which of your nostrils is more open and moving air more quickly? Put two of your fingers right below your nostrils (not in them!) and try to breathe normally. Can you feel more air coming out of one nostril? The amount of air might be very close in each so it may be difficult to tell, but try and breathe as normally as possible.
Check back in few hours and see if your nostrils have switched roles. How often do they switch?
