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In reality, colors are a mere invention of our brain. When sunlight falls on an object, it is reflected and then captured by the retina in our eyes. This stimulus travels to the brain, where we receive it as colors.
Whether an object appears red or blue depends primarily on the nature of its surface. This determines which light waves are reflected and which are absorbed. Because light is made up of electromagnetic waves of different wavelengths, each color has a different wavelength.
Birds can see even more colors than we can
The fact that we can distinguish between yellow, red, and blue is due to the sensory cells in the eye called cones. The three different types of cones in the human eye can each receive a specific wavelength-and therefore one of the three primary colors. When light of different wavelengths is reflected from an object, a mixture of colors is created. For example, when light with wavelengths corresponding to yellow and red hits the retina, the brain perceives the color orange.
Incidentally, the world is even more colorful for most birds than it is for us, as their eyes are equipped with four types of cones and can even perceive UV light. There are probably evolutionary reasons for this: Some fruits reflect UV light as they ripen.
How animals actually perceive color, however, remains unclear. Researchers can measure their response to color stimuli, but not their perception of color in the brain. As a result, the nature of color, like the beauty of the world, is in the eye of the beholder.
