Why are there no blue cows in the world?

Looking at the colors of nature is truly awe-inspiring. The magical blue color of the feathers of a merganser sitting on the bank of a river or the bright blue pattern of the wings of a butterfly flying over a flower always fascinates us. This wonderful blue color can also be seen in the world of insects and birds around us. But now let's take a look at the other side. Just look at the big animals around us! Do dogs, cats, cows, horses, tigers, lions or monkeys appear blue? Or have you ever seen a dog or cat with bright blue fur like a merganser? Of course not. But why is this so? Why don't mammals have this blue glow in their bodies?

In the animal world, colors are mainly produced in two ways. The first way is through dyes or pigments. Our skin, hair, fur or bird feathers contain these pigments. These pigments create specific colors because of these pigments. For example, a pigment called melanin causes black skin. If someone lacks this pigment at all, it is called albinism. If this pigment is missing, the animal is completely white.

Mammals have two main types of common pigments: eumelanin and pheomelanin. Eumelanin gives animals their black and brown fur. Pheomelanin, on the other hand, gives them a reddish-brown hue, which we see in red or yellow fur. The various combinations of these pigments give mammals different shades, stripes, or color variations, and these colors can change with age. But notice that there is no blue pigment in the list of these pigments!

The second way to create color is structural color. There is no pigment involved; rather, when light falls on the internal structure or structure of fur or feathers, it is reflected in a way that looks like a specific color. This structural color is most commonly used in insects like butterflies or birds like flamingos.

Now you might think, there is a lot of color variation among monkeys. There are even mammals like blue monkeys, blue whales, and blue wildebeests! So why are they called that? Actually, their skin color is not truly blue. Their body color is basically slate gray. Because of this color, animals can appear a bit bluish when viewed from a distance in certain environments.

Shannon Farrington, senior keeper at ZSL London Zoo in the UK, said that like humans, other mammals are also dependent on their evolutionary history. Is it very important for animals to have blue or green skin or pink eyes for their survival? Will blue help them survive better than they do now? In fact, through thousands of years of evolution, animals have received exactly what they need to survive in nature. In other words, nature did not give them blue color because blue color does not give them any additional advantage in the fight for survival.

 But there are some surprises in this too! A type of monkey called the mandrill has a very beautiful touch of blue on its face. But there is no blue pigment here either. The collagen protein fibers in the inner cells of the mandrill's skin are arranged so perfectly that when light falls on them, it reflects blue. According to Shannon Farrington, this extraordinary mixture of blue and red on the face and back of the male mandrill is mainly created to attract a mate and show their dominance.

The same phenomenon is seen in the case of vervet monkeys. Their bodies also have a blue color due to their structure. In scientific terms, this law of light scattering is called the Tyndall effect. This effect is named after the person who discovered why the sky looks blue. Although later Lord Rayleigh did more detailed research on the subject. Therefore, it is also known as Rayleigh scattering. This Tyndall effect is also behind the blue color of the human eye. But there is no blue pigment in the blue eyes of humans!

That is, there is no pigment or dye in the body of mammals that can produce blue color. Therefore, there is no mammal in this world that is truly completely blue in color.