One of the most mysterious systems in the human body actually sends signals you can see all over your skin: goosebumps. Those tiny pins of flesh can rise when you’re suddenly spooked by something, when you hear an inspiring song, or when you’re cold. How do so many different things trigger the same response? And why?
Goosebumps are a reaction of the nervous system, which is responsible for all of your senses; it channels a steady stream of information between your brain and body, interpreting everything you see, hear, smell, taste, and feel. But just why goosebumps appear is traced to something a little less elegant: our animal ancestors.
As George A. Bubenik, a professor of zoology (of course!) explains over on Scientific American: Tiny muscle contractions cause your skin to round up when you get goosebumps; they also make every hair stand straight up. This was useful when we had more fur for a couple reasons. For one, it helped to keep us warmer when cold and, for two, made us look bigger when scared. Next time you see a dog and cat cross paths, watch for the fur on their backs to rise as they size each other up.
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