science: Humans get their color vision from three kinds of cone cells in the eyes, with response curves centered around the wavelengths we perceive as blue, green and red. As a result, the color space we can perceive is three-dimensional. Birds have four different kinds of cones, and so they can distinguish more shades of color than humans. It is, in a sense, the opposite of color blindness. And...
I am free, no matter what rules surround me. If I find them tolerable, I...– Robert A. Heinlein (via ruineshumaines)