Some say it could be a warning for others to stay sharp.
Asked by: Kanika Ahuja, Winchester
This is part of our fight-or-flight response and happens when our sympathetic nervous system releases hormones, including adrenaline, which activates sweat glands. Brain scans reveal that sniffing someone else's panic-induced sweat lights up regions of the brain that handle emotional and social signals. So one theory is that this sweating is an evolved behaviour that makes others' brains more alert and primed for whatever it is that's making us anxious - handy if there's a marauding tiger on the loose.
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Dr Emma Davies is a science writer and editor with a PhD in food chemistry from the University of Leeds. She writes about all aspects of chemistry, from food and the environment to toxicology and regulatory science.
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