Why we have two nostrils instead of one big hole
https://www.popsci.com/science/why-we-have-nostrils/Open linkView original on toast.ooohttps://www.popsci.com/science/why-we-have-nostrils/Open linkView original on toast.ooohttps://www.popsci.com/science/why-we-have-nostrils/Open linkView original on toast.ooo
We have stereo smell to help with locating smells. There's also the nasal cycle. One nostril/sinus handles most of the airflow, then they swap (the sinuses are separate until they get to the throat). That way one can recover moisture, plus some smells are more easily detected with fast airflow and others with slow. So the nostrils functioning differently gives us a broader range of odor detection. What else? Umm, bilateral symmetry and redundancy is useful.
This guy nose.
Knows his noses.
Nobody nose it, but you've got a secret smile...
The same reason we have two eyes and snakes have forked tongues.
... So the snake can lick both our eyeballs at the same time before biting us on the nose?! Also two snake fangs, two human nostrils, aaahk it's twos all the way down!
Snakes smell with their tongues.
Since we use our nose to warm incoming cold air, I'm sure cutting the volume per nostril and boosting contact surface makes a significant difference
Wtf do you mean the swap?!?!?
Yeah, if they could both work at the same time though, that'd be ideal.
So that we know which side to lay on because one is clogged?
Bilateral symmetry, hox genes.
If you do enough cocaine, you can end up with one nostril. It happened to a British TV celebrity in the 90s.
Happened to Steve-o too I believe
This is the first thing I thought of too when I read the post. Though presumably this doesn’t answer the question from an evolutionary perspective - ENS happens when you alter the normal anatomy. If it evolved that way hopefully the creature would perceive that as normal.