It's amazing how we can perceive all of the different colors of the world with just three microscopic cones found in our eyes. These color detecting cones were discovered in 1964 by Brown & Wald. Each cone is sensitive to different wavelengths of light. Color blindness is caused when a person loses the function or is missing of one or more of the cones due to genetic abnormalities or traumatic brain damage. 
The person is then not able to recognize certain colors. By only having one cone in your eye, you are considered to be a monochromat, which only allows you to see the world in black and white. A dichromatic person is only missing one type of cone, resulting in the loss of only a few colors.Animals such as cats and dogs are dichromatic normally and can only distinguish a few colors. Red-Green color blindness is the most popular type of color loss, occurring mostly in males. Often times it goes unnoticed because it does not really interfere with someone's everyday life. When visiting the eye doctor, you might notice a chart of circles that looks like this. If you cannot read all of the numbers located in the circles, then you may just be color blind, so take a good look, and maybe read a little bit more on the subject matter!
