Certain Christmas legends require a suspension of disbelief, but a new paper published by Frontiers for Young Minds ("science edited for kids, by kids") reveals that Rudolph’s iconic red nose isn’t one of them—at least not entirely.
Dartmouth College anthropologist and evolutionary biologist Nathaniel J. Dominy here delves into the unique characteristics of Rangifer tarandus tarandus—specifically, how their eyes are well-suited to winter navigation. Unlike humans and most other mammals, Arctic reindeer are able to see ultraviolet light, which is a useful trait to have during those months of the year when the Sun is low on the horizon and light is scattered high in the atmosphere, making it UV and blue-purplish.
Additionally, reindeer have reflective tissue in their eyes that changes color with the seasons. Golden in the summer, the tissue turns to deep blue in the winter, which is believed to help the animals see blue light. The tissue also improves their ability to see in the dark and makes their eyes shine at night.
So, if reindeer basically have superhero sight, couldn't any random reindeer lead Santa's sleigh? Nope. The problem is fog. As you’ll recall, in Robert L. May’s original story, it was a foggy Christmas Eve when Santa came to say: “Rudolph with your nose so bright / won’t you guide my sleigh tonight?” Reindeer are hindered by the fog, which makes purple and blue light practically invisible. Red light, on the other hand, travels well in fog and would be extremely helpful for guiding an airborne sleigh with a planet’s worth of presents. Rudolph’s luminescent snout would be a perfect solution. The final optical benefit comes with the specific red of the nose, which is compared in one version of the story to the color of holly berries. That level of red is quite possibly the maximum redness that the eyes of mammals are able to see. In other words, Rudolph’s nose is perfectly engineered for the task at hand.
There is one small problem. Reindeer noses are vascular, which means they lose a lot of body heat through their schnozzes. Rudolph with his nose so bright might be prone to excessive heat loss, with a risk for hypothermia. The good news, writes Dominy, is that we can do something to help: "It is therefore extremely important for children to provide high-calorie foods to help Rudolph maintain his body temperature on Christmas Eve.”
You heard him. Prepare your plates of milk and cookies accordingly.