Humans are colorblind at night. But there are people who cannot differentiate between certain colors even during the day. They suffer from a condition called colorblind people are able to see things and colors as clearly as other people but they are unable to fully see red, green or blue light. You would be amazed to know that all babies are born colorblind mostly on objects very close to him. All of what to see comes in three basic color combinations black, white, and shade of grey. His vision improves in a few weeks and he is able to see colors as well.
Did you know bulls are colorblind? They charge the red cape because it is moving, not because it is red!