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The average person experiences dozens of individual itches each day. We’ve all experienced the annoyance of an inconvenient itch — but have you ever pondered why we itch in the first place? Is there actually an evolutionary purpose to the itch, or is it simply there to annoy us? Emma Bryce digs deep into the skin to find out.

Lesson by Emma Bryce, animation by Sashko Danylenko.