The majority of humanity has 'Rods' and 'Cones' in their eyes. Rods allow us to see light, dark and shades of gray. It's the rods which allow us to see in the dark. Cones on the other hand, allow us to see color. Most of humanity have rods which allow them to see red, blue and green light. These are the building blocks of the visible spectrum that we see around us. With properly functioning cones, the average person can see 1 million color variations.
Mutations can cause colorblindness in males which affect the red-green ends of the spectrum and those afflicted either can't see those colors or see them altered. They only have two rods so the numbers of colors A recently discovered mutation found to primarily affect women born with a 'fourth cone' (Red, Blue, Green, ?) that allows them to see 100 million colors. The mutation is carried on the 'X' chromosome so though extremely rare, women are much more likely to carry the gene than men with their single X chromosome.
Here's an article that reveals in small part what information has been found so far and a link for a test to see if you may be a 'Tetrachromat'....
nice drop, thanks wolfgang
Thanks. This comes straight out of sci-fi (only it's real.) There is speculation as to what use the ability is useful for when for the most part the world seems to be designed for 'trichromats' (three color cones.) Even that is not necessarily 100% since most animals can only see in black and white. Insects and many other invertebrates can see into the ultraviolet range where they see patterns and colors we can't. The tetrachromats can see colors those with three rods can't. It's an amazing discovery because there are people walking around with this ability and probably have no idea that they have it.