In order for a wrinkle to develop, you need loose skin.  This is called the aging process which is the laxity of the skin over a certain amount of time. At 25, the eyebrows start moving downward over the ridge of the eye.  This causes a saggy, droopy appearance.  At 30, the nasolabial folds (starting at outer bottom edges of the nose towards the corners of the mouth) become more prominent as they deepen.  At 40, forehead wrinkles begin to appear and crow's feet begin their etch at the outer corners of the eyes.  At 50, the outer corners of the eyes start to slope downwards and the nose starts to droop.  Also, the appearance of wrinkles around the mouth and neck start to show and the cheeks begin to hollow due to fat loss.  At 60, the eyes may look smaller because of the folded skin and from here on, it is a continuous process due to fat absorption and elastic reduction. 

Why does this happen?

Skin is a composite tissue, consisting of a fibrous matrix containing elastin and collagen.  Collagen provides strength to the skin structure and elastin provides the "snap" or resiliency, allowing the skin to move about and assume conformational changes as required.  When changes occur, the elastin fibers lose their resiliency or snap and the skin is no longer able to return to its original state.  As a result, sagging and crinkling occur in a pattern that is called wrinkles.

What are the causes of wrinkles?

Sun exposure tops the list.  You must, at all times, protect your skin from both UVB and UVA irradiation.  The sun's rays denature the total cellular structure which results in profound abnormal structures.  Just one bad sunburn is all it takes to produce substantial wrinkles, though it will take 15 to 20 years to show itself. 

Smoking cigarettes causes free radical damage and is one of the major causes of abnormal proteins in the body.

Drinking excessive amounts of alcoholic beverages at a certain level is toxic to the body.  Alcoholics and habitual drinkers have a very dry, dull yellow skin that shows the ravages of the underlying tissues.  

Soap-based products have side effects on the skin because the most common emulsions used of this type are stearic acid and triethanolamine.  Manufacturers use it because it is inexpensive.  The pH of these emulsions are often higher than pH 8, which is one hundred times the pH of skin.  It is meant for cleaning the face but it removes essential lipids, the natural skin oils, at the same time.  It also reacts with the keratins of the skin, denatures them, and causes them to lose functon.  This produces the dry, tight feeling.  There is no doubt that it is a contributing agent to wrinkles.