Aug 3, 2017

We Could Be on the Threshold of a New Era of Color Science

Sunset over the colorful tulip fields in Karatay, Konya, Turkey on April 13, 2016.
An international team of 27 scientists has just declared that we are on the threshold of a new era of color science that could have far-reaching impacts on everything from the security industry to our understanding of animal and human behavior.

The declaration, published in the journal Science, follows multiple advances in the study of animal and plant coloration.

“New technology is opening new windows into exploration of color perception, production, and function,” senior author Tim Caro of the University of California, Davis, said.

Co-author Justin Marshall of the University of Queensland recently determined that mantis shrimp have four times as many color receptors as humans do. He explained that we have three — red, green, and blue — while the shrimp have twelve.

Lead author Innes Cuthill of the University of Bristol said mantis shrimp use those extra color channels to analyze light coming from objects in ways much different than humans and most other animals.

“They analyze light like a machine called a spectrometer, which a physicist would use to measure how much light there is in a set of wavebands,” he said. “We, and most other animals, instead transform the relative amounts of light in different wavebands into a single continuous percept: the sensation we call color.”

Peacock mantis shrimp (Odontodactylus scyllarus) photographed in the Andaman Sea, Thailand
Animals see the world differently than we do. For example, no human has yet set eyes on “bird white.” What we think of as “white” could also be something completely different to a bird.

“Objects that all look white to us may look different to a bird depending on how much ultraviolet light there is,” Cuthill said. “If there’s as much UV as blue, green, and red, that would be ‘bird white.’ If there was no UV, then that would be a saturated primary color to a bird, one we cannot imagine.”

Another recent finding in the field of color biology suggests patterns of color on a species can signal how well an individual can fight. Co-author Elizabeth Tibbetts of the University of Michigan first noted that black facial patterns vary on paper wasps. She then discovered that females with larger or a greater number of irregular black marks on their faces tended to win fights with their rivals.

Tibbetts explained that the facial signals help reduce the costs of conflict.

“Lots of animals have color patterns that convey information about fighting ability: birds, lizards, fish, mammals, insects,” she said. “It’s the animal version of advertising your fighting prowess with karate belt color. If you are a wimpy wasp, it doesn’t make sense to challenge the strongest wasp in the neighborhood to a fight.”

European paper wasp
Body coloration can be tied to many behaviors. Humans are not exempt from the color-behavior connection. In fact, many people who head to a sunny climate for spring or summer vacation may exemplify the phenomenon.

Caro explained that skin color in humans is the result of a trade-off between avoiding the harmful effects of ultraviolet radiation and the beneficial effects of vitamin-D production caused by sunlight hitting the skin.

“This trade-off can affect behavior,” he continued. “For example, people in northern European climates like to take advantage of the sun in spring and sunbathe to produce vitamin D after the long winter.”

Color in nature is usually tied to honest visual information. Human heritage, in this way, is reflected in an individual’s skin color.

Read more at Seeker

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