Reshared post from KQED SCIENCE:

Original Post from KQED SCIENCE:

Is Nail Biting a Pathology? Or Just a Bad Habit?

Nail biting -- like skin picking and hair tending -- stems from an evolutionarily adaptive behavior: grooming. But in "pathological groomers," as they're known in in the world of psychiatry, that healthy urge goes haywire. 

Learn more in our new KQED QUEST radio story: http://goo.gl/tgAan