1. Is there any particular reason/advantage in having two nostrils?
No, there is no particular advantage to having two nostrils (if we define the word as specifically as we can and mean two "openings" into the nasal cavity.
2. What would happen if someone only had one nostril?
If that nostril served both chambers of the nasal cavity, nothing untoward would happen.
3. Why do humans have two nostrils?
Most animals, including humans, are bilaterally symmetrical. This means that the right and left sides are mirror images of one another. Thus both sides develop somewhat independently of each other. Having said that I have to emphasize the word "somewhat," since there is a great deal of interrelationship, interaction, and communication between the two sides for normal development to occur. Thus, as the face develops, two nasal placodes (thickenings of the frontal process) develop. These begin to submerge and as they do, each placode results in the formation of a nasal chamber, and the region surrounding each placode forms a horseshoe-shaped thickening, known as the nasal process. Each nasal process is subdivided into a lateral and a medial nasal process, which partially surround the opening into nasal chamber. Since it is a horseshoe-shaped structure, it will require a closure at its open end and that closure results from the fusion of the lateral and medial nasal processes with the developing maxillary process.
I hope this helps.
Leslie P. Gartner, Ph.D. Associate Professor of Anatomy Dental School University of Maryland Baltimore, MD
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Ответ номер два.
No, there is no particular advantage to having two nostrils (if we define
the word as specifically as we can and mean two "openings" into the nasal
cavity.
2. What would happen if someone only had one nostril?
If that nostril served both chambers of the nasal cavity, nothing untoward
would happen.
3. Why do humans have two nostrils?
Most animals, including humans, are bilaterally symmetrical. This means
that the right and left sides are mirror images of one another. Thus both
sides develop somewhat independently of each other. Having said that I have
to emphasize the word "somewhat," since there is a great deal of
interrelationship, interaction, and communication between the two sides
for normal development to occur. Thus, as the face develops, two nasal
placodes (thickenings of the frontal process) develop. These begin to
submerge and as they do, each placode results in the formation of a nasal
chamber, and the region surrounding each placode forms a horseshoe-shaped
thickening, known as the nasal process. Each nasal process is subdivided
into a lateral and a medial nasal process, which partially surround the
opening into nasal chamber. Since it is a horseshoe-shaped structure, it
will require a closure at its open end and that closure results from the
fusion of the lateral and medial nasal processes with the developing
maxillary process.
I hope this helps.
Leslie P. Gartner, Ph.D.
Associate Professor of Anatomy
Dental School
University of Maryland
Baltimore, MD
Re: Ответ номер два.
Мне интересно не объяснение, каким образом в носу появляются две дырки, а в чём тут смысл :-)
Re: Ответ номер два.
Думаю, смысл в ответе номер один :)
Re: Ответ номер два.
Почему бы ноздре не быть по центру?
Re: Ответ номер два.
Думаю, так сложилось.
http://news-service.stanford.edu/news/1999/november10/smell-1110.html