A fatal railway 1875 accident in Sweden that killed nine people was believed to be caused by a color blind rail operator who failed to properly read a signal. After the crash, a method to test color v
Color blindness is hereditary, and is passed from mother to son on the 23rd chromosome. However, it can also be caused by eye diseases, aging or retina damage.
Dogs, cats, and rabbits see mostly gray. Monkeys have strong color vision while bees and butterflies have superior vision and can see colors humans can't even see.
Not a lot of people, but some, suffer from a rare form of color blindness called unilateral dichromacy which means they have one normal seeing eye, and one color blind eye.