Why does skin wrinkle in water?

Answer: Nervous system causes constriction

Loss of natural oils — Wrong. Water does wash away oils, but wrinkles form from nerve-controlled blood vessel constriction, not just oil loss.

Nervous system causes constriction ✓ — Correct! Wrinkled fingers aren't passive water absorption—they're active nervous system response! Blood vessels in fingertip/toe skin constrict under autonomic control, pulling skin inward and creating wrinkles. Evidence: nerve damage prevents wrinkling. Purpose: improved grip on wet objects (like tire treads). Evolutionary advantage for handling wet items!

Osmosis draws water out — Wrong. Osmosis would work opposite direction. Wrinkles are active nerve-controlled vasoconstriction creating grip-enhancing treads, not passive water movement.