It's Not the HOW . . . It's the WHY

. . . I ask myself this question:

WHY do we see in color?

When I ask my very intelligent computer this question, something to this effect always comes up -

The cells in our eyes called cones are sensitive to the wavelengths found in the visible spectrum. They allow us to see the all the colors of the rainbow.

These cones respond to light with varying wavelengths, which correspond to different colors.
The brain processes these signals and translates them into the colors we perceive.
Light is made up of different wavelengths, each corresponding to a different color in the visible spectrum.
Our eyes have three types of cone cells,
each sensitive to different wavelengths of light (short, medium, and long). 
When light enters the eye, it stimulates the cones, and they send signals to the brain through the optic nerve. 
The brain processes these signals from the cones, comparing their activity levels to determine the color we perceive.

Considered to be part of the brain itself, the retina is covered by millions of light-sensitive cells, some shaped like rods and some like cones. These receptors process the light into nerve impulses and pass them along to the cortex of the brain via the optic nerve.

Rods are most highly concentrated around the edge of the retina. There are over 120 million of them in each eye. Rods transmit mostly black and white information to the brain.

Cones are concentrated in the middle of the retina, with fewer on the edge. Six million cones in each eye transmit the higher levels of light intensity that create the sensation of color and visual sharpness. 

These light-sensitive cells, working in combination with connecting nerve cells, give the brain enough information to interpret and name colors.

Can you imagine being in charge of counting the millions of rods and cones in the eye? Not a job for me.

This is all very informative, even interesting - BUT - I asked a different question . . .

WHY do we see in color?

I already have my answer.
My answer is EASY.

We can EXIST without seeing in color.

Our world would be seen in black, white and various / multiple shades of gray
(or grey, if you prefer).

“The sky is such a lovely shade of gray this morning.”
Stop lights - black, white and gray.
Flowers and tree leaves - all various shades of gray. Butterflies attracted to light grays; hummingbirds attracted to dark grays - or visa versa.
What is this year’s shade of gray? Interior designers can work around this shade.

Our lives would be as if watching TV prior to 1954, when color televisions made their debut.

After a coughing spell, trying to catch my breath;
I don’t take my breathing for granted.

While weed whacking the yard, flying bits of grass scratching my eyes;
I don’t take my vision for granted.

I can hear very well, it’s just that I don’t always know which direction the sound is coming from.
Listening carefully; I don’t take my hearing for granted.

BUT COLOR . . . I never take for granted.

The color mint green calms my soul.

Bright red excites my heart.

Trees would all blend into each other if there weren't so many shades and hues of green to separate the trees from each other.
Leaves aren’t just light green in the spring, and darker green in the summer.
Leaves aren’t  just green.
Leaves are hues, shades and tints of white, yellow, green, blue, purple, even red.

The impressionist (oil painters, that is) were the first to incorporate scientific discoveries of their day into their paintings.
Monet's use of complementary colors allowed him to create harmonious compositions that shimmered with light. Complementary colors such as red next to green.
Understanding that shadows were cool in tone and that blue was preferable to black for creating shadow colors.
By incorporating these scientific principles into their work, the Impressionists were able to achieve a greater sense of realism and luminosity in their paintings.

And we, as visitors to museums, get to appreciate these beautiful works of art - in full color; in living color.

We would not miss color, IF no one could see color.
Would we evolve into color seeing humans, if there was no NEED to see in color?

We COULD EXIST in a black, white and various shades of gray world.

Yes, it is possible to exist without seeing in color. 

Complete Achromatopsia or Monochromacy, describes someone who can only see shades of black, white, and gray.
This is a rare form of color vision deficiency, where individuals have no ability to see colors at all, and it is usually inherited or acquired from injury / illness.
As the description states, achromatopsia is rare, however people can exist without seeing colors.

So - Back to my original question :

If it is possible to EXIST in a world of black, white and various shades of gray, 

THEN . . .
WHY - Do we see in color?

As I mentioned earlier, my belief is EASY . . .

It is a GIFT.