There are many factors that contribute to the development of wrinkles.
Free radicals are molecules that lead to the degeneration of collagen, a protein found in the skin that keeps it elastic and healthy-looking. Free radicals are found in the UV radiation in sunlight, smoking and air pollution.
Changes in hormones also produce changes in the skin. Menopause and decreased estrogen production can affect the skin's elasticity and also cause fine lines.
Muscle use, including everyday expressions like frowning and smiling, also leads to wrinkles while the effects of gravity loosen the skin, causing it to sag.

How Wrinkles Form
As we age, the cells in the epidermis (the outer layer of the skin that protects us from the elements) become increasingly thin and decreasingly sticky. As a result, our aging skin becomes thinner and drier; cells divide more slowly, meaning that the natural repairing mechanisms in the skin work less quickly. Changes also occur in the dermis, the second layer of the skin, where the connective tissue is found. The connective tissue controls the strength and elasticity of the skin, as well as the proteins found in it. In our aging skin, the dermis becomes thinner and collagen production is decreased. Elastin fibers decline, leading to decreased elasticity.

There are a number of causes for wrinkles, folds which appear in the skin over time. People often associate the development of wrinkled skin with age, and the aging process definitely plays a role in the development of wrinkles. There are some steps which people can take to reduce wrinkling of the skin, and some products purport to limit wrinkling and erase wrinkle lines. These products work with varying degrees of success, and people who are interested in them should consider talking to a dermatologist about their options.

As people age, their skin undergoes a number of changes. The cells in the epidermis, the upper layer of the skin, start to divide more slowly, making it difficult for the skin to repair itself, and the epidermis thins. Both process make skin more papery and fragile, and they contribute to water loss. When the skin is not able to stay as moist, dehydration can contribute to the formation of wrinkles.

Wrinkling is also associated with a loss of skin elasticity, another thing which occurs over the course of time. Muscle movements can also hasten the formation wrinkles, with habitual muscle movements creating creases which will eventually become permanent. The face and hands are often heavily wrinkled for this reason, because they are used abundantly over the course of someone's lifetime.

The skin's supply of nutrients is also interrupted by the aging process, and activities such as smoking can make this problem even worse. This contributes to wrinkle formation. Wrinkles also become pronounced because fat cells shrink with age, and they no longer act as a form of natural wrinkle filler which keeps the skin plump and tight.

Damage from sunlight is a big cause of wrinkles, especially in areas where the ozone layer is thin. Wearing sunscreen can protect people from wrinkles and prevent skin cancers. Natural hormonal changes which occur with age are also a cause of wrinkles, especially in women, as changing hormone levels can lead to issues such as skin dryness.

Wrinkling is also associated with a loss of skin elasticity, another thing which occurs over the course of time. Muscle movements can also hasten the formation wrinkles, with habitual muscle movements creating creases which will eventually become permanent. The face and hands are often heavily wrinkled for this reason, because they are used abundantly over the course of someone's lifetime.

The skin's supply of nutrients is also interrupted by the aging process, and activities such as smoking can make this problem even worse. This contributes to wrinkle formation. Wrinkles also become pronounced because fat cells shrink with age, and they no longer act as a form of natural wrinkle filler which keeps the skin plump and tight.

Damage from sunlight is a big cause of wrinkles, especially in areas where the ozone layer is thin. Wearing sunscreen can protect people from wrinkles and prevent skin cancers. Natural hormonal changes which occur with age are also a cause of wrinkles, especially in women, as changing hormone levels can lead to issues such as skin dryness.