Why?Nostrils?

Question

Why do we have two nostrils instead of one in the middle of our noses?

Answer 1

In biology, the answer to any question that begins with "Why ..." is "Because evolution made it that way." The trick it to figure out what the problem was that evolution was solving.

A second thing to realize is that living things generally resemble their ancestors. In this case, if you look around, almost all vertebrate animals have two nostrils ... meaning that we - all of the vertebrates - are descended from a species that solved some problem of survival by making two nostrils where one might have been enough.

So what was the original problem? The problem was how to locate things by smell. The solution was to use two nostrils and compare what they were each smelling to find the direction that the odor was coming from. More odor on the left side meant that was the direction to go to find food or a mate. If the nostrils were both detecting the same amount of odor, the source was either directly in front of or behind the fish. One nostril would be a less efficient way to detect this information.

Why do I say fish? Well, I don't know for sure, but I don't think animals lower than fish have nostrils in the way that the higher animals do, and fish certainly have two nostrils. Also note that fish do not breathe through their nostrils - they breathe using their gills - and so the original use of nostrils was not to breathe.

So: I think the full answer is that we have two nostrils because we have inherited that body plan from early fish which evolved two nostrils so that they could track odors in the water.

Humans are not very good at tracking things by smell, so I doubt any of us would be conscious of the relative strengths of odors in each nostril, but perhaps an animal like a hound dog might still use it's nose and brain this way.

BTW: your brain compares the time at which a sound arrives at each ear in order to determine the direction the sound came from, and your brain also compares the visual images it receives from each eye in order to judge the distance to an object - these mechanisms are similar to the way a fish deduces the direction to swim to get to food by comparing the strength of odor in each nostril.

Answer 2

Good question

well ,as you know the nostril is the main inlet
for breathing
Functions of the nose ;
it is the top part of our respiratory system ;
The nasal passages have a good blood supply ,
so the when air is breathed in.
the air is moistened and warmed ,

Little hairs in our nostrils ( vibrisea)
filter and sweep out unwanted particles
( that may otherwise get into the lungs )

the adenoids, lay at the base of the nose
they help to fight bacteria

The septum (divide between our nostrils)
adds extra surface area ,
to warm and moisten the air efficiently

All this, is a lot of work, to ask of one poor nostril!
so we have two .

We would look very odd, with one nostril alone-- LOL!!!!

If nostrils both get blocked , as in a heavy cold .....

we can still breath through our mouth ,
but, the air is dry----
and makes our throat sore,when we do ,
and we feel awful, ( all bunged up)

>^,,^<

Answer 3

When we breathe we only use one nostril, and the nostril we use changes around every 10 minutes. This is to give the mucus a chance to break down after catching all of the particles so that we do not constantly breathe through all of the germs we have been breathing in. If we only had one nostril then this would be the case, and so we would be more prone to disease.

Answer 4

For practical reasons. if you only had one your nose would poke out farther, it would be harder for the nose to be designed with as much structeral integrity with only one nostril and with only one it would be too easy for a mouse to crawl up it while you sleep. Also the internal diameter of twin nostrils are the most effacacious for the speed at which breath is breathed in, this is important because it is the speed of the air flow over snot in the nose which dries it and turns it into bogies or boogers as the Americans call them, when dry enough they simply fall out on the carpet uness you find other means of removing them first. Also witth twin nostrils the surace area of the nose inerior is greater still further assisting the drying of bogies and also allowing more fine interier nose hairs to be present in order to trap any dust or other foriegn bodies that otherwise may enter the body through the nose. Obvious really.

Answer 5

The scientific reason of having 2 nostrils instead of one because 1 nostril is used for inhaling oxygen from the air and the other one is used for exhaling carbon dioxide

Answer 6

Human embryonic development is that two primitive noses join in the middle. Two nostrils are like two ears , eyes, etc

Answer 7

Because God wanted us to have two just in case one side of your nostrils was plugged up you could still breathe. If you had one big one, you wouldn't be able to breathe at all (if you were sick of course).

Answer 8

I guess its because we have 2 lungs 1 nostril for each lung.

Answer 9

If a single one got blocked up you would be in trouble.
It is like having two engines on an airplane.

Answer 10

this thing is for scientists to worry about not u ! we have two because we have two!!!haha