Your skin's structural foundation depends on collagen, which provides tensile strength, and elastin, which allows skin to snap back after movement. Starting around age 25, collagen production declines by approximately 1% per year. By your 40s, you may have lost 20-30% of your dermal collagen, and this decline accelerates significantly after menopause, with women losing up to 30% of their remaining collagen in the first five years.
Repetitive facial expressions create dynamic wrinkles -- the lines that appear when you smile, squint, or furrow your brow. Over decades, the underlying muscles etch permanent creases into thinning skin that can no longer bounce back. Crow's feet, forehead lines, and glabellar frown lines (the "elevens" between the brows) are classic examples of expression-driven wrinkles that gradually become visible even at rest.
Ultraviolet radiation compounds this process through photoaging, which accounts for up to 80% of visible facial aging. UV exposure generates free radicals that break down collagen and elastin fibers while simultaneously suppressing new collagen synthesis. This damage accumulates over years, eventually manifesting as deep creases, crepey texture, and uneven skin tone layered on top of natural age-related changes.
