We know that our skin is the largest part of our body. It consists of two important layers – dermis (the middle layer) and epidermis (upper layer). Scientists have come up with different theories as to why wrinkles appear on fingers and toes.
Theory number one says it is because of the epidermis layer which protects the blood vessels and other tissues beneath the middle layer dermis. The epidermis is further classified into four layers of which stratum corneum acts the outermost layer. This layer contains dead keratin cells. Keratin is a protein found in hair, nails and outermost layer of skin. While the fingers or toes are in contact with water for a considerable period of time, dead keratin cells absorb water causing the skin to swell. This layer is strongly attached to the deeper layers and so the increase in surface area is compensated by wrinkle formations.
The other theory makes the narrowing of blood vessels below the fingers and toes responsible for the wrinkles. When hands are soaked in water, the nerves are made to shrink and the body temperature regulators on the skin decreases in volume and causes wrinkling pulling the skin downwards.
Whatever reason could be, the fingers with wrinkles are said to have a better grip than when they are dry.