Fine lines and wrinkles are caused by the breakdown of collagen and elastin in the skin. Collagen and elastin provide the support structure for skin, helping to keep it smooth and resilient. As these fibers break down, the skin begins to lose its strength and elasticity. When this happens, fine lines and wrinkles can begin to appear. For most, exposure to the sun's damaging UV rays is the major cause of skin aging resulting in fine lines, wrinkles and rough texture. Heredity, the natural aging process and even years of facial expression can also play a role. Most people first notice fine lines and wrinkles around their eyes and mouth.