Final answer:
Fingers wrinkle in water due to an involuntary nervous system reaction that causes blood vessels to constrict, resulting in the skin forming ridges that improve our grip. This process is related to the body's response to prolonged wetness and is an evolutionary adaptation. Wrinkling of the skin is also a natural aging process related to the loss of elasticity and moisture retention.
Step-by-step explanation:
When fingers are submerged in water for a period, they often wrinkle due to the skin's reaction to prolonged wetness. Initially, it was thought that osmosis caused the cells in the skin of the fingertips to swell up and wrinkle. However, more recent studies suggest that this wrinkling is an involuntary reaction controlled by the nervous system, which constricts blood vessels beneath the skin. This vasoconstriction leads to negative pressure that pulls the skin into ridges, enhancing our grip on wet objects. The reaction might be an evolutionary adaptation, similar to tread on tires, to improve traction and handling in wet conditions.
Wrinkling is part of the aging process where the skin loses its elasticity and ability to retain moisture, resulting in the breakdown of its structure. This is due to decreased collagen and elastin production, weakening of the underlying muscles, and reduced activity of accessory structures and cells like melanocytes and dendritic cells that contribute to skin tone and immunity.