I'm no social scientist, so i'm being a layman here. THe comment re: the green ink was joke, but a study reported in the Times did say that there seemed to be link.

But doesn't nature attribute colours to emotion or patterns of behaviour, our cheeks become red when angry, indicating a danger that violence may ensue, many dangerous creatures, and those that wish to appear so, are red in order to discourage attack, although predators are less likely to be so as they would wish to conseal their threat, not advertise it.

Like i say, i'm pleb in these matters, so feel free to totally discredit me, as i'm sure someone will :D