Is it a silly question to ask *why* we see the orders of colors the way we do in the visible spectrum with respect to wavelength? For instance, I know that comparisons to dogs are often made with the following visible spectrum comparisons: [PLAIN]http://www.psychologytoday.com/files/u162/dog_color_vision.png [Broken] Notice how we still have yellows at longer wavelengths than the blues. Or a bee's vision (ability to see UV light): [URL]http://img.dailymail.co.uk/i/pix/2007/08_01/WoodDM0708_468x137.jpg[/URL] Or snake infrared sensors: http://en.wikipedia.org/wiki/Infrared_sensing_in_snakes At any rate, what seems important to me is that wavelengths don't have any particular color encoding in them by definition -- it's just that our brains are sensitive to a particular threshold of wavelengths and then they chop up that threshold into visible colors, ranging from red colors to violet ones (and in that order, the interesting part to me). My question is, though, is there any reason our brains do this? Why are the colors of the spectrum the way they are? As in, why are longer wavelengths encoded to be shifted towards red/orange/yellow colors whereas shorter wavelengths are encoded to be shifted towards green/blue/violet colors? Why couldn't the spectrum be inverted altogether? I am not asking that question to invite a "Well, if it were the other way around, you'd be asking the same question" response -- to me, such a response is no different from asking why the moon is round ("no matter its shape, you'd be asking that question"). I am still after the underlying explanation, which we can offer for the moon -- but can we offer it to color, as well, or is it still a huge unknown?