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Michael: Suppose you’re angry. Really angry. Like... someone-just-destroyed-your-almost-finished-jigsaw-puzzle kind of angry. Well, in that case, you -- or the person you’re mad at -- might notice that your face will turn red... as though your blood were ready to boil, and steam was about to whistle out of your ears.

Well, I can tell you for sure that it’s physiologically impossible for steam to come out of your ears. But what you’ve just exhibited is a nervous system response. Specifically, a response to a threat. Even though, looking back, having your puzzle ruined wasn’t really threatening, was it? But try telling that to your nervous system! When something causes you immediate stress -- even something mildly upsetting -- like if someone wrecks your sandcastle, or spoils that Darth Vader is Luke’s father, your sympathetic nervous system can recognize this as a threat, and activate a fight or flight response.

This response affects your whole body, preparing you to either fight the threat, or run away from it. And it happens not only when you’re angry, but also when you’re embarrassed, or nervous. It’s just that -- in the case of being angry -- your reaction is more “fight” than “flight.” Either way, you pretty much see the same things happen: Within a few seconds, your pupils grow large, your heart beats faster, and blood vessels all over your body widen, to increase blood flow. This allows more blood to reach your muscles, providing them with more oxygen, and preparing them for action -- whether that’s putting up a fight, or running away. As a result of all this, the vessels in your face also widen, allowing more blood to flow in. And these vessels are very close to the surface of your skin. So the extra blood might actually show through, creating reddish, rage-filled cheeks.

The effects tend to be most noticeable in people with lighter skin, but the same response happens to everybody, no matter the color of their skin. And unfortunately, the whole process happens at the command of the sympathetic nervous system -- which means it’s involuntary and uncontrollable. Scientists are still learning what, if any, evolutionary function this response -- known as flushing -- might have, especially because humans seem to be the only animal that has it. It’s likely that this redness has been useful in helping us communicate our emotions. When your face turns red, the people around you have a better idea of how you’re feeling -- which helps you socially. So next time you glow an angry red, just know your body’s trying to express itself. And, you know, don’t freak out, it’s just a puzzle.

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