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Scratching May Have an Evolutionary Purpose, But You Still Need to Resist the Urge

Scratching can be beneficial, but learn more about how in most cases, the harm outweighs the benefit.

ByAvery Hurt
(Image Credit: AYO Production/Shutterstock)

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Ever had poison ivy? If so, you probably noticed that scratching made the rash much worse. But scratching an itch, especially one as intense as that caused by poison ivy, is nigh irresistible — and feels so satisfying.

If you think about it, says Daniel Kaplan, who is a dermatologist and immunologist at the University of Pittsburgh, that’s a little curious. When comparing this action to pain, pain causes you to stop what you’re doing and tend to the wound. But the pain also creates a memory that tells you not to repeat whatever you were doing when you got hurt — or to wear gloves the next time you prune the roses.

“From an evolutionary standpoint, there’s a clear and obvious benefit to that pain,” he says. But with scratching, the damage feels good. It’s as if when you cut yourself with a knife, you were immediately compelled to ...

  • Avery Hurt

    Avery Hurt is a freelance science journalist. In addition to writing for Discover, she writes regularly for a variety of outlets, both print and online, including National Geographic, Science News Explores, Medscape, and WebMD. She’s the author of Bullet With Your Name on It: What You Will Probably Die From and What You Can Do About It, Clerisy Press 2007, as well as several books for young readers. Avery got her start in journalism while attending university, writing for the school newspaper and editing the student non-fiction magazine. Though she writes about all areas of science, she is particularly interested in neuroscience, the science of consciousness, and AI–interests she developed while earning a degree in philosophy.

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