Feast after flight: Study shows reindeer’s eyesight evolved to spot favorite foods

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Concord, New Hampshire, may have millions of carrots ready for Rudolph the Red-Nosed Reindeer on Christmas Eve, but what about the rest of the year?

Finding food in cold, barren lands is a challenge, but researchers at Dartmouth College in New Hampshire and the University of St. Andrews in Scotland report that reindeer eyes may have evolved to allow them to spot themselves easily Favorite food.

Nathaniel Dominy, a professor of anthropology at Dartmouth and co-author of a recent study published in the journal i-Perception, said this is further evidence that although reindeer are famous for pulling Santa’s sleigh well-known, but what really sets them apart is their vision.

“They’ve been obscure and obscure in the annals of visual neuroscience, but they’re having their moment because they have very fascinating visual systems,” he said in an interview.

Scientists have known for years that the mirror-like tissue in reindeer eyes changes color from green-gold in summer to bright blue in winter, a process thought to amplify the low light of polar winter. But they didn’t know what to make of another strange fact: Unlike other mammals, reindeer can see light in the ultraviolet spectrum.

“Most animals that are active in daylight want to avoid UV rays. UV rays are damaging,” Domini said. “Snow reflects UV rays, which is a problem, and that’s why humans suffer from snow blindness.”

Some scientists believe that reindeer’s vision evolved to protect the animals from predators, allowing them to spot white wolves in snowy landscapes, for example. The new study points to another possibility: food.

Reindeer live primarily on light-colored reindeer moss, which is not actually a moss but a type of lichen that grows in crunchy, carpet-like patches in northern latitudes.

The researchers traveled to the Cairngorms in the Scottish Highlands, home to more than 1,500 species of lichen and Britain’s only reindeer herd. They found that reindeer moss absorbs ultraviolet light, meaning the white lichen, which is difficult for humans to see in the snow, appears dark on the animals.

“If you’re a reindeer, you can see it and you have an advantage because then you’re not wandering the landscape. You can walk in a straight line and get food, and you save energy in the process,” Domini said. said. “These animals desperately need food, and if they can find enough lichens, then they have an advantage.”

Juan José Negro specializes in evolutionary ecology and conservation biology at the Spanish Scientific Research Council. Although he focuses primarily on raptors, he finds the new caribou research interesting.

“I love every piece that involves color and visuals,” he said. “Every time I read other people’s work, it sparks new ideas. In the case of reindeer, it makes me want to focus more on that part of the spectrum.”

He said that while he doesn’t think the research will have immediate biomedical benefits, this type of work can help further our understanding of how animals cope with difficult environments.

Domini agrees, but says it also has implications for humans. Due to their antioxidant properties, lichens have been extensively studied pharmacologically. Reindeer’s eyes allow ultraviolet light, suggesting there may be some mechanism that protects them from harm, he said.

“Reindeer eyes are rich in ascorbic acid, or vitamin C, and vitamin C is very effective in repairing damaged cells,” he said.

With that in mind, Domini is updating his recommendations following a 2015 paper that explored why reindeer’s red noses are ideal for guiding Santa’s sleigh.

At the time, he suggested that the kids leave out Rudolph cookies and other high-calorie foods to make up for the body heat he was losing through his nose. Now, he said, focusing his eyes on leaving the milk and cookies for Santa.

“To protect eye health, it’s best to feed them something rich in vitamin C,” he said. “Orange juice, carrots, perfect food for the reindeer on Christmas Eve.”

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