why do we have two eyes for vision and not just one ?
Answers
With one eye, the world looks flat, i.e., two dimensional only. With two eyes, the view is three dimensional, i.e., dimension of depth is added to our view
Answer:
There are many advantages of having two eyes instead of one. Some of these are given below.
1. Having Two Eyes Gives a Wider Field of View. A human being has a horizontal field of view of
about 150° with one eye open but with two eyes open,
the field of view becomes 180°. Thus, having two eyes
gives a wider field of view. This means that with two
eyes open, we can see a much larger area in front of us
(than can be seen with only one eye).
The human beings have two eyes at the front of their
head, so their field of view is limited to about 180°. Some animals, however, have their two eyes
located on the opposite sides of their head. Those animals who
have two eyes on the opposite sides of their head have the widest
possible field of view. They can see much larger area around them
than the human being can see. The animals of prey (like rabbit,
deer, chicken, fish, etc.) have their two eyes on the opposite sides
of their heads so that they can see their enemies (predators) in a
very large area around them and try to escape from them . A domestic animal having its two eyes on the opposite
sides of the head is horse.
2. Having Two Eyes Enables Us to Judge Distances More
Accurately. Our two eyes are a few centimetres apart from each
other . Due to this, the two eyes see the same object
from two slightly different angles and send two slightly different
images of the same object to the brain. The brain combines these two slightly different images to build a
three-dimensional picture of the object which enables us to judge the distance of the object more accurately.This will become clear from the following example. Let us take two sharpened pencils, one in each hand.
Stretch the arms forward and try touching the tips of pencils first with one eye open and then with both
eyes open. We will find that it is difficult to touch the tips of two pencils with one eye open but it is much
more easy when both the eyes are open . This is because with both the eyes open, we can
judge the distances of the pencil tips more accurately. Human beings (and all other animals having their
eyes at the front of their head) are said to have stereoscopic vision (or stereopsis) which gives the perception
of depth. All the predators (like tiger, lion, etc.) have their eyes at the front of head so that they can judge
the distance of their prey accurately and catch them easily .