Why do we like to scratch a wound when it's healing?
Forbidden pleasure
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Why do we like to scratch a wound when it's healing?
Asked by Nikki Boyle of Newtown, NSW, Australia
Scratching an itch is a puzzling biological and behavioural response in any case. It is especially odd to scratch a healing wound since logic would indicate that scratching would hinder rather than help the healing.
One theory of why we itch suggests that scratching stimulates the release of endorphins. These are naturally occurring opiates which block pain sensation. We release a flood of endorphins to block the pain of the initial injury, while the scratching only injures our skin only a little more. The gain from the endorphins thus outweighs the loss from the slight injury.
Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au
COMMENTS
More speculation
Maybe the wounds just taste good. Maybe it's the salt in the blood. Check it out - lick your wounds!
So how come these animals can overcome the scratching urge like that? Maybe they don't itch? There again, my dog scatched her eczema to shreds and then licked the wounds.
Maybe there's evolutionary value in not knowing these things?
Licking, not scratching
Well, most animals do not scratch wounds - they lick them. The itching reminds them to keep the wound clean and moist.
itching to reply
"If scratching really does have shown negative effects (infection, slowing of tissue growth etc.) then evolution usually has the complexity to work around it."
There again, evolution may not be all it's cracked up to be. Maybe itching - and consequent scratching - is just a ba-ad thing that doesn't help us at all. Maybe we'd all be much better off if we didn't do it. Maybe all those sabre-toothed tigers were even more itchy than we were. Maybe itchy wounds are caused by wolf genes "reaching out into the world" a la Dawkins to weaken their prey. In a world without references or personal biographies anything is possible.
I thought the itching was just the bits of torn tissue beginning to join up again.

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