From various studies I've seen, the human eye sees best, or responds most to the frequencies of green. It may have been discussed before, but I would guess that is a result of a selection preference to determining different kinds of plants - what's poisonous and what's not.
Also, designers know that blue falls to the background. But do they know it's for the same reason the sky is blue? The farther something is, the more blue light is scattered. our eyes and brain have adapted to to our environment.