Have you ever stepped out of a long bath or spent hours swimming only to notice your fingertips looking pale, wrinkled, and almost unrecognizable? Photos like this often go viral with dramatic captions suggesting something is seriously wrong. In reality, the explanation is usually much more ordinary.

Many people believe their skin wrinkles simply because it absorbs water, but scientists have discovered that’s not the whole story. The wrinkling is actually controlled by the nervous system. When your hands stay in water for an extended period, your blood vessels narrow, causing the skin on your fingertips to pucker into the familiar wrinkled pattern.

Researchers believe this response may have a useful purpose. Wrinkled fingertips appear to improve grip on wet objects, much like the tread on a tire helps it hold onto a wet road. It’s thought to be an evolutionary adaptation that made it easier for our ancestors to gather food or move across slippery surfaces.

In most cases, these wrinkles disappear within a short time after your hands dry and warm up again. However, if your fingers become severely wrinkled without being exposed to water, or if the changes are accompanied by pain, numbness, swelling, or discoloration, it’s a good idea to consult a healthcare professional to rule out an underlying condition.

So while these fingers may look shocking at first glance, they are usually just the result of spending too much time in water. It’s a completely normal response for most people and one of the many fascinating ways the human body adapts to its environment.