What causes wrinkles?
Years of repeated facial movements eventually leave their mark on your skin. As the muscles in your face move to form expressions, your skin stretches and presses against itself. This leads to creases, lines, and folds that will eventually form over areas of high muscle activity.
For example, folds can develop around the sides of your mouth from smiling. Fine lines can creep up near the outer corners of your eyes due to squinting. These signs of aging may look almost imperceptible at first, but they will inevitably become more deeply set — and permanent — over time.