As both the earliest and the most obvious form of facial aging, fine lines and wrinkles occur on every face eventually. Despite their inevitability, though, they don’t all come from the same place.

When most people think of their facial aging, they think of it as the result of natural deterioration of the skin. For many types of wrinkles, that’s pretty accurate. This type of wrinkle is called a static wrinkle, and it occurs when essential skin components like collagen, elastin, and hyaluronic acid disintegrate naturally over time. This process is often accelerated by factors like excessive tanning, smoking, and other activities that damage the skin. Combined with the effects of gravity over time, this weakening of the internal structure of the skin causes slackening and loss of volume that leads to fine lines, drooping skin, and wrinkles.

The other, less-known type of wrinkle is called a dynamic wrinkle. This type of wrinkle is also fundamentally caused by the deterioration of the healing compounds in skin, but instead of coming straight from gravity, it is caused by repetitive movements that crease the skin. Dynamic wrinkles form in areas of the face where the muscles are particularly active and include common wrinkles like horizontal lines on the forehead, furrows between the eyebrows, and crow’s feet at the outer corners of the eyes. Over time, dynamic wrinkles turn into static wrinkles as the aging skin stops bouncing back from repeated facial expressions.