Key points

We scratch itches and hold injuries because those responses reduce discomfort.

Relief comes because activation of touch receptors "gates off" itch and pain signals in the spinal cord.

Touch activates descending pathways from the brain to the spinal cord to further inhibit itching and pain.

Touching irritated or damaged skin also activates reward centers in the brain.

When I was a kid, my mom would say, “Don’t scratch that itch, it will only make it worse.” And multiple elementary school teachers told me, “Holding an injury doesn’t help. Leave it alone.”

But it seems that my body knew some neuroscience that my parents and teachers didn’t: that scratching and grabbing actually do help, which is why evolution wired those adult-annoying behaviors into us.

Let’s start with i

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