Science: Why are fruits so colorful?

From pink and green watermelons to the deep blues and purples of blueberries, fruits come in more shades and hues than any other food. Why is that?

Past theories have suggested that fruits as a whole developed in such a rainbow-esque way in order to attract the attention of animals, who spread their seeds by way of eating them. A bright red pop of a berry cluster is easier for a bird to see in a sea of green foliage, after all.

While a common theory, it’s been hard to back up with scientific evidence (especially when considering that animals perceive color differently from us).

“With the exception of a handful of other primates, no other animal on Earth sees color the way that we do,” said Duke University’s Kim Valenta, co-author on a recent study that examines the animal-attraction theory.

Valenta, along with colleagues from the U.S. and Germany, collected data on fruit and leaves from nearly 100 Ugandan and Madagascan plants. Their goal was to examine all the factors that might have influenced the color, from environmental factors like temperature, soil properties and even genetic considerations. Did berries only grow to be pink because their closest genetic relatives did?

The researchers concluded that among closely related plant species, fruit colors are just as varied as they’d expect from non-related plant species. That said, fruits mostly eaten by mammals reflected more green light and fruits mostly eaten by birds reflected more red light, suggesting that animals really might have played a role in shaping fruit color.

Their evidence also suggested that environmental factors play a role in fruit color. Plants with ultraviolet light-reflecting fruits were found to have leaves that did the same thing, which could be tied to sun protection. Some fruits may have become the colors that they are in order to better block harmful rays.

Of course, there’s more to plants than color. The researchers intend to continue their work by looking at how odor, size and texture of fruits might attract hungry animals.

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