Study suggests reindeer vision evolved to spot favorite food
Concord (US), Dec 23: Rudolph the red-nosed reindeer may have millions of carrots set out for him on Christmas Eve, but what about the rest of the year? Finding food in a cold, barren landscape is challenging, but researchers from Dartmouth College in New Hampshire and the University of St. Andrews in Scotland report that reindeer eyes may have evolved to allow them to easily spot their preferred meal.
It’s further evidence that while reindeer are famous for pulling Santa’s sleigh, it’s their vision that really sets them apart, says Nathaniel Dominy, a Dartmouth anthropology professor and co-author of a recent study published in the journal i-Perception.
“They’ve been sort of obscure and unheralded in the annals of visual neuroscience, but they’re having their moment because they have a really fascinating visual system,” he said in an interview.
Scientists have known for years that mirror-like tissue in reindeer eyes changes color from a greenish gold in the summer to vivid blue in the winter, a process that is thought to amplify the low light of polar winter. But they weren’t sure what to make of another curious fact: Unlike other mammals, reindeer can see light in the ultraviolet spectrum.
“Most animals that are active under daylight conditions want to avoid UV light. UV light is damaging,” Dominy said. “Snow reflects UV light, which is a problem, which is why humans get snow blindness.” Some scientists believe reindeer vision evolved to protect the animals from predators, allowing them to spot white wolves against a snowy landscape, for example. The new study points to another possibility: food.
Reindeer subsist largely on light-colored reindeer moss, which isn’t actually a moss but rather a type of lichen that grows in crunchy, carpet-like patches across northern latitudes. Researchers traveled to the Cairngorms mountains in the Scottish Highlands, which hosts more than 1,500 species of lichen as well as Britain’s only reindeer herd. They found reindeer moss absorbs UV light, meaning the white lichen that humans have trouble seeing against the snow stands out as dark patches to the animals. (AP)
