Michael Aranda explains why human beings blush, while animals don’t, in the latest Quick Questions by SciShow. Charles Darwin referred to the trait as, “the most peculiar and most human of all expressions.”
Your face turns red because your sympathetic nervous system kicks in. That’s the network of nerves that controls your fight-or-flight response. When it’s triggered, it signals the release of adrenaline. Suddenly your heart rate picks up and you start breathing faster and then you’re ready to run away.