The British Medical Journal is one of the world's oldest and most respected academic publications. So it would only make sense for the much vaunted journal to take on one of the season's most vexing questions: Why on earth would a reindeer have a red nose?
It took seven professors who specialize in otolaryngology, the treatment of ear, nose and throat conditions, to tackle the question. In "Why Rudolph's nose is red: observational study," the researchers suggest that the well-known reindeer's nose is red has a basis in biology: Reindeer have significantly higher blood flow to the nose as do other mammal species, such as humans.
To come to that conclusion, the scientists compared how microcirculation, the delivery of fresh blood to small blood vessels like the one in the nose, works in reindeer and human noses. How does one measure blood flow to a reindeer's nose? According to this paper, it involves "gently inserting an imaging probe, covered with a sterile disposable lens cover, into the nasal cavity."
Microcirculation is the reason that human noses turn red in the cold; there's a rush of red blood cells into the nose. The researchers found that level of microcirculation is 25 percent higher in reindeer than in humans, meaning their noses are "richly supplied with red blood cells." You can sort of see that in this image, which shows the various temperatures of a different parts of a reindeer's head.
"Rudolph’s nose is red because it is richly supplied with red blood cells, comprises a highly dense microcirculation," the researchers conclude, "And is anatomically and physiologically adapted for reindeer to carry out their flying duties for Santa Claus."