We may never know exactly why Rudolph the Red-Nosed Reindeer's nose glows -- but we have a few scientific suspicions. Learn about bioluminescence and atavisims in this episode of BrainStuff, based on these articles: https://animals.howstuffworks.com/animal-facts/bioluminescence.htm; https://people.howstuffworks.com/culture-traditions/holidays-christmas/rudolph-red-nose-reindeer.htm

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