It's important that our eyes differentiate yellow from green because leaves are green and things that aren't leaves may be yellow. It's completely possible that we could have more colors or less. That whole dogs are color blind thing.
Color vision predates our species so niggers likely see color too
A colour could be defined in a couple of different ways. You could define it by its wavelength, and it could also be defined according to the beholder's perception - here I'm thinking of the Himba tribe who consider blue to be a shade of green, or the Russian people who consider dark blue and light blue to be separate colours, just like English speakers consider red and pink to be separate.
I'm just thinking about the definition of color and how it relates to Race.
Color vision predates our species so niggers likely see color too
http://grindgis.com/wp-content/uploads/2015/05/Electromagnetic-Spectrum.png