Why is the bluebird blue?

I used to have a co-worker who refused to eat blue M&M’s. She ate all the other colors, but the blue ones went in the trash can – unless someone willing to eat the blue ones was on hand to take them. I found this behavior very strange – what difference does it make what color the M&M is? But Sue did not eat anything that was blue, arguing that no food is that color naturally.

What about blueberries? She pointed out that they’re not really blue. The skins are more purplish, and the inside is some shade of green. I tried and tried, but couldn’t come up with any food that is naturally a true blue. For that matter, there’s not much in nature that has blue pigment at all.

You probably know that the sky appears blue because of how light is scattered in the atmosphere, though I learned today that it’s even more complicated than I had thought. In a similar way, the ocean looks blue because it absorbs the other colors of the light spectrum more than it does the blue light.

I found out from this web page about the chemistry of the color blue that

Blue is rare in living nature as it is a colour that is associated with organic molecules in alkaline conditions: few living systems have an alkaline chemistry.

Where, then, I wondered, did artists get the stuff to make blue paint from? It turns out they had to use ground up lapis lazuli, which was very rare and very expensive. I never thought about it much before, but I’m guessing that when I have visited museums with lots of old paintings, I didn’t see much blue.

By the time I was growing up, blue paint and blue crayons, made using synthetic compounds, were easy to come by. My 64-color box of Crayola crayons had several shades of besides the basic blue: cornflower, midnight blue, turquoise blue, periwinkle, aquamarine, cadet blue, sky blue, and navy blue – not even counting color blends such as green blue, violet blue, and blue gray. I used lots of blue coloring the sky and water, never imagining that it had not always been so easy to do.

Today my favorite color is blue. (As a child I chose to have my room painted yellow, with orange trim, because I thought of those as cheerful colors. Years later I decided my older sister had probably chosen better with light blue walls and darker blue trim.)

I like blue clothes, blue cars (though I have never owned one, since I always buy used cars and choose for value, not color), the default blue color scheme in Windows, and blue towels, sheets, and blankets. Other colors have shades that I don’t much care for (e.g. mustard yellow, olive green), but all shades of blue look good.

I must not be alone in my preference. The Crayola Color Census 2000 found that

Americans’ favorite Crayola crayon color is blue.  Six other shades of blue finished in the Top 10 including cerulean, midnight blue, aquamarine, periwinkle, denim and blizzard blue. 

I had been thinking about doing a blog post on this topic recently, since reading Jasper Fforde’s Shades of Grey and thinking about how colors are made and used. But it was just yesterday, reading the current copy of Smithsonian while exercising on the elliptical machine, that I came across an article about how birds with blue feathers acquire that color.

There is no blue pigment in their feathers. Instead, the feathers are made up of keratin arranged around air pockets. Different shades of blue come from different patterns in the structure of the keratin.

I can’t help wondering whether there is any meaning to the fact that the color so many people seem to like best is one that is so rare in nature. If birds find blue attractive, I suppose it should not be too surprising that humans do also.

Then again, perhaps we like blue because we do see blue so much in nature – in the sky and the water – even though there is no blue pigment there. My favorite combination of colors is blue, green, and white – like the sky, trees, and clouds.

In any case, now you know why the bluebird is blue.

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3 Responses to Why is the bluebird blue?

  1. Peter L says:

    Maybe that is why I recently found that the indigo bunting is my new favorite bird.

  2. Peter L says:

    That reminds me about the other colors of corn. We think of it as yellow, but in nature it is red, blue, white and yellow.

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