The sensation of color is an interpretation by the brain of the reaction of retina in the eye to different wavelengths of electromagnetic radiation. If received in certain proportions, several combinations of radiation with wavelengths between 400 and 800 nanometers produce a sensation of white; any imbalance in these proportions produces color. A leaf looks green because it absorbs red and violet, leaving most of the yellow, green, and blue radiation that together add up to green. Red objects absorb energy at the blue end, leaving the red end of the radiation spectrum. Humans only see radiation between 420 and 800 nanometers, while other animals see other ranges.
Fruit colors cover the full visible spectrum from blue to red. The green color of plants is due to chlorophyll, a pigment essential for conversion of light energy into stored energy. Not surprisingly, the base color of most fruit is green, due to chlorophyll. Although some fruit stay green, others change color during ripening, a process that enhances their attractiveness to humans and to birds. Fruit color changes attract birds and occur after the seeds are mature enough to develop into new plants, resulting in effective seed dispersion. Frequently, ripening involves changes in sugar concentration and flesh texture, which also make the fruit more attractive to birds. Seed-eating birds appear to prefer black and red fruit, and many native fruit are these colors.
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