This month's Smithsonian magazine that arrived this last week contained a lot of food for thought. Well, it always does, but somehow each issue has one article that peaks my interest more than the others.

For a long time I've known about color as a powerful communication tool for humans. It can signal action, influence our own and others' moods and cause psychological reactions. Certain colors are specifically used for those powers. For instance, there was a particular bridge that for some reason attracted suicides; the rate of successful jumpers was very high compared to all other bridges. The decision was made to paint the entire bridge pink, and like magic, the suicide rate there went down drastically. Sometimes rooms in prisons are painted pink, for the same reason: pink has been shown to be a calming, even tranquilizing, color.

On the other hand, red tones, including red, orange and yellow, evoke emotions ranging from warmth and comfort to anger and hostility. I am quite sure no one ever painted rooms in prisons in any red color. Red is the color of love, hence red is big around Valentine's Day. Red cars are considered targets for thieves and are stolen more often. Showing students red prior to taking tests has a negative impact on performance during the tests. The color red causes people to react with greater speed and force, so it is a good color for athletes. On the other hand, sports teams wearing black uniforms receive more penalties.

Blue and green are, for humans, considered cool colors, likely because that is the color of the sky and the ocean and forests. Blue is the most popular color, and people are more productive if they work in blue rooms. When streetlights are blue, the crime rate is lower. Dark green is considered the color of masculinity and wealth; maybe that is why our country's money is green.

It has been shown that babies cry more, and people lose their tempers more, in a yellow room. Maybe a yellow room can help us lose weight, because yellow speeds our metabolism.

Purple is the color of luxury, sophistication and royalty.

Black is the color of authority and power, but also can signal submission. Priests wearing all black are signaling their submission to God, and it has been suggested that women who wear all black are signaling their willingness to submit to men, thus it is common for "ladies of the night" to be attired all in black.

White is the color associated with innocence and purity, and traditionally doctors and nurses wore white to demonstrate sterility. Imagine the message being sent now when hospital staffers wear what looks like kiddies' pajamas! Because it reflects all light rays, white is considered a summer or hot weather color.

I remember well the "rule" that we wear white only between Memorial Day and Labor Day, and I admit to thinking twice just this week when trying to decide whether I was going to wear white slacks for an occasion.

In the magazine that arrived this week, there was additional information about how humans respond to color ("This month we're thinking about color" Smithsonian, Sept. 2013). For instance, the average hours of sleep per night in yellow bedrooms was 7.7 and in purple bedrooms was 5.9.

Men will increase the tip given to waitresses who wear red instead of green or black by an average of 26 percent. But women will not increase the tip at all for a waitress wearing red instead of green or black.

As mentioned, purple is known as the color of luxury, sophistication, and royalty. I guess there is good reason: it is a color that is rarely found in nature, and "in the ancient world, 10,000 tropical sea snails were required to make one gram of royal purple dye."

What most fascinated me in this issue was the information about animals and color. It said that mantis shrimp have 13 types of color-sensitive photoreceptors, while humans have only three.

Amy Maxmen wrote, "Although colors exist only in the mind's eye, they create a universal language." She used as an example the strawberry poison dark frog whose "vivid hues" send the message that "If you eat me, it could be the last thing you ever do!"

Citing a study by Molly Cummings at the University of Texas, she said that "the frogs' colorations have been shaped by an unusual combination of pressures to both avoid predators and win mates....The more poisonous the frog, the more conspicuous its colors." For them, they are literally "dressed to kill." They are in contrast to an animal like a peacock, whose "colorful tails are a hit with the ladies," but those same tails make it difficult for them to fly away from danger.

We humans have a choice as to what colors we wear and use. Now I am wondering if somewhere deep down in our buried psyches we choose colors for the same reason: to avoid predators and attract mates.