Minor quibble: I think it's the other way around (redder = longer wavelength)
Derp, yeah, I always get those mixed up.
Another possibility is that we grow to like colours that we subconsciously associate with nice things red is also the colour of danger and sweet blushes. Or angry ones
I think the ubiquity of the red effect points to nature rather than nurture. Also, red is only the colour of danger because humans decided that it should be so. Why did they? Because humans are already sensitive to red.
They may be, indirectly. The sun's peak energy output lies around the greenish wavelengths, so being extra sensitive to greenish photons will make life a little easier for animals who see (and being less sensitive ie. reflecting green photons will make life easier for plants who want to avoid sunburn ). Sensitivity to green and red may also have been especially advantageous in our ancestral environments, whether we're talking about forests or the savannah.
Good guess, but like Loki, I think the answer is no. The second factor related to vision is
the absorption spectrum of water. Animal vision takes advantage of the fact that wavelengths between 300 and 700 nm are the least absorbed by water. Green light, 500 nm, is able to pass through water the easiest! Since life evolved in the water, animals would have to have the ability to see through water first and foremost, which I think explains why our vision (and that of all animals) is centered around green light. We're out of the water
now, but light still has to pass through our eyes, which are of course mostly water.
The biological reason we're more sensitive to green, by the way, is because rhodopsin, the light-sensitive molecule in the retina, is excited by light according to a normal distribution. Green light is at the center of that curve, and red and violet are more to the sides. But given the absorption spectrum of water, I think the reason that animals evolved rhodopsin that's sensitive to green light, rather than some other light-sensitive molecule, is because it lets you see through water.