Human physiology?!
Question:
Why do we have two eyes?
Why do we have two ears?
Why do we have two nostrils?
Answers:
ask Darwin
Other Answers:
Two eyes and two ears-- Having one for a back up. Two eyes gives 3 dimentional viewing.
As for 2 nosterals, not sure.
EYES
MadSci Network: Evolution
http://www.madsci.org/posts/archives/feb99/920061344.Ev.r.html
Re: Why do all fish, mammals, reptiles and birds have exactly two eyes?
"In summary, animals that have two eyes have them because of two
reasons. All vertebrates with eyes have two because the common
ancestor of vertebrates had two eyes. That common ancestor had two
eyes for the same reasons that invertebrates with eyes tend to have
only two complex eyes: two eyes are better than one because they allow
comparison of light coming from two directions, while a third eye
doesn't give enough extra information to make it worth the costs of
having it."EARS
Two Ears Are Better Than One
http://www.starkey.co.uk/pages/learn/learnHearing2.html
Why do we have two ears? Much like having two eyes helps us to see all
around us, having two ears helps us locate sound in time and space.
Balanced or binaural hearing is vital to your ability to locate where
a sound is coming from. The brain instinctively locates a sound’s
source by measuring the tiny differences in duration and intensity in
the way each ear hears the sound.
*****
"Q: Why do we have two ears?
Http://freda.auyeung.net/5sens.
A: We have two ears because the sounds hits one ear a fraction of a
second before the other and produces stronger vibrations. It helps
you tell what direction the sounds come from."NOSTRILS
MadSci Network: Development
http://www.madsci.org/posts/archives/jan2000/947001218.Dv.q.html
"Question: Why do humans have two nostrils?
Is there any particular reason/advantage in having two nostrils? What
would happen if someone only had one nostril?"
Answer:
http://www.madsci.org/posts/archives/jan2000/947001218.Dv.r.html
"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."
Answers: