Opposite colours.

Green and red are opposite colours, and that is important! Why?

The theory goes like this... Humans evolved from tree dwelling apes that lived in a green world where the dominant colour was created by the green chlorophyll in the leaves. The plants couldn't much avoid having green leaves. But plants wanted tree dwellers to assist in plant reproduction by eating and spreading their seeds. So the cunning plants coloured the seeds in the opposite colour, red, to make it easier for the seed spreaders to find the seeds. The seed spreaders, that includes you and me, evolved at the same time with a visual system that had the ability to recognise the useful plant colouring system and get the rewards included in the clever plant strategy, namely bright red ripe sweet fruit.