Why are plants green? The answer to this is some pretty basic physics.
The colors of light that we receive from the Sun have different energies. Red is the lowest of these energies followed by yellow, green, and blue. The sunlight with the highest energy that actually reaches the surface of the Earth is green. Blue light, which is more energetic, is refracted away by Earth’s atmosphere and scattered as it interacts with molecules in our upper atmosphere. That’s why the sky is blue.
When you look at an object, the color you see is the color reflected by that object. A red ball is red because it reflects red and absorbs all other colors. A green leaf is green because it reflects green and absorbs all other colors. If the highest energy of light reaching the surface of the Earth is green, and if the leaf reflects green, what does this do for the leaf? The answer should be pretty obvious – it keeps the leaf from absorbing too much energy and getting cooked. In the fall of the year when the leaves lose their chlorophyll A, which gives them the green color, what happens? The leaf gets cooked, falls off the tree, and we have to scrape it off the yard.
If a planet had a different atmosphere so that a different energy of light reached its surface, its plants would have to be a different color. To quote Kermit the Frog “It’s not easy being green.” Why are plants green? They are green because green is essential to life on Earth.
This explanation is greatly oversimplified. Obviously, not all plants have green leaves. Some plants live under a canopy of other trees and have to use a different system. The design of life on Earth is incredible, and the green trees and grass around us testify to the wisdom of God in making a place for life to exist.
There are many differences between men and women, but you realize that there are color vision gender differences?
Light is electromagnetic radiation that stimulates our eyes. There are only specific frequencies of the electromagnetic frequency spectrum that we can see. Frequencies below the range of visible light are called infrared. We can sometimes feel infrared radiation as heat, but we can’t see it, although some animals can. Frequencies higher than visible light are ultraviolet which we can’t see, but it affects our skin and can cause sunburn. Some animals can see infrared light.
Within the visible spectrum of light that humans can see, different bands of frequencies affect our eyes differently. Most of us have receptors in our eyes for the wavelengths which we call red, green, and blue. When light stimulates those receptors, they send a signal to our brain which combines the signals to allow us to see many variations in colors.
People with colorblindness (mostly men) have one of those color receptor categories missing. The missing color may be either red or green. Why are men colorblind more often than women? The genes that encode the red and green receptors are located in the X-chromosome. Men have one X- and one Y-chromosome. Women have two X chromosomes. That means that if a man has a defective X-chromosome, he is out of luck. A woman would need to have two defective X-chromosomes to be colorblind.
Some of the most beautiful colors you will see are found in birds and butterflies. We usually think of color as coming from pigments or dyes which reflect specific colors of light. However, the most intense and beautiful colors in the feathers of birds and the wings of butterflies don’t come from pigments. These animals display beauty in structural color.
Microscopic structures create structural color within the bird’s feathers or the butterfly’s wings which interfere with the frequencies of visible light. For example, the pigment in a peacock’s feathers is brown, but when you look at a peacock, you see blue, green, and turquoise in unusual patterns. Structural color can create color effects more intense than pigments, and structural color doesn’t fade like pigments. Structural color can even create an effect called iridescence in which colors change depending on the viewing angle. You can see this effect when you look at a CD or DVD.
Our ability to see the incredible color in the world around us is amazingly complex. We don’t actually see color with our eyes. We see color with our brains.
Most humans have trichromatic vision. Our eyes only detect red, green and blue. If our eyes detect a lot of red and green but not much blue, our brains decide that we are seeing yellow. When our eyes register equal amounts of red, green, and blue, our brain decides that we are seeing gray. If red and blue are present, but not much green, our brain decides we are seeing purple.
Some of us do not have red or green receptors in our eyes, especially people with XY chromosomes (males). We call it color blindness, but in reality, our eyes just don’t see one particular set of wavelengths. Some of us with XX chromosomes (females) may have tetrachromacy which means we see more than the three primary colors.
In the animal world, color is produced by many different techniques. The wings of the Morpho butterfly appear to be blue or violet depending on how the light strikes them. This is due to light-scattering scales that cover the insect’s wings. Dragonfly wings look similar to the Morpho wings, but the dragonfly’s color comes from waxy crystals that cover layers of the pigment melanin. We call the method of color production in these insects “structural color” because it is produced by the structure of the material rather than by pigments. Cameleons also use structural color using nanocrystals in their skin. They can tune the nanocrystals to reflect different colors. In this way, they can match the color of their environment or their mood.
One of the joys of life is the beauty that we see in the natural world. The beauty of flowers is so great that we decorate our homes inside and out with flowers of every description. People will get out of bed early in the morning to watch a sunrise display colors of incredible beauty and complexity. We admire the work of artists and photographers who can capture a permanent record of the colors of the world on canvas or film. Why is there color in the world?
There are hundreds of papers that have been written by scientists and science writers concerning the reason for color. The design of the Earth and of the life systems on Earth frequently demand that certain colors exist. For example, the green in vegetation is necessary to protect plants from the high energy wavelengths of the Sun’s light.
There are some colors in the natural world, however, that seem to defy a naturalistic evolutionary explanation. Flowers living in identical environments will frequently have radically different colors. If we postulate that the colors are different to attract different pollinators, we run into logical problems. Wouldn’t the most efficient pollinators provide the same advantages to all flowers of similar geometric design? In caves deep in the ocean, there are some of the more vividly colored tropical fish. These fish never see sunlight and have no camouflage advantage given by their colors. There are worms and burrowing animals in thermal vents deep in the floor of the ocean that display rich and beautiful colors.
A skeptic may reply that these colors are a chance consequence of the materials that make up the bodies of these organisms. The fact is that, in many cases, the colored materials in the organism are inconsequential to the survival of the organism. We would suggest an equally plausible and perhaps more realistic explanation. Could it be that a God of intelligence and creative power designed the creation not only with functional wisdom but also with aesthetic intelligence?