It's been known for a while that certain injuries can cause cancers, but the reasons why are still foggy. Now, new research shows at least part of the answer when it comes to skin cancer. Follicular stem cells, associated with the spots on your skin that grow hair, are generally dormant. But when you get a scrape or cut on your skin, those stem cells flock to your wounds as part of the healing process.

When those stem cells arrive at your wound, they reawaken - sometimes in a pretty damaged state, full of cancer-causing mutations. Though these follicular stem cells might never have caused you trouble, your wound has now caused cancer-causing cells to start replicating. Suddenly they're causing basal cell carcinomas to pop up on your skin. And this is why some skin cancers start with just a small scrape on your skin.