<P> The subcutaneous tissue (also hypodermis and subcutis) is not part of the skin, and lies below the dermis of the cutis . Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves . It consists of loose connective tissue, adipose tissue and elastin . The main cell types are fibroblasts, macrophages and adipocytes (subcutaneous tissue contains 50% of body fat). Fat serves as padding and insulation for the body . </P> <P> Human skin shows high skin color variety from the darkest brown to the lightest pinkish - white hues . Human skin shows higher variation in color than any other single mammalian species and is the result of natural selection . Skin pigmentation in humans evolved to primarily regulate the amount of ultraviolet radiation (UVR) penetrating the skin, controlling its biochemical effects . </P> <P> The actual skin color of different humans is affected by many substances, although the single most important substance determining human skin color is the pigment melanin . Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker - skinned humans . The skin color of people with light skin is determined mainly by the bluish - white connective tissue under the dermis and by the hemoglobin circulating in the veins of the dermis . The red color underlying the skin becomes more visible, especially in the face, when, as consequence of physical exercise or the stimulation of the nervous system (anger, fear), arterioles dilate . </P> <P> There are at least five different pigments that determine the color of the skin . These pigments are present at different levels and places . </P>

How many surface layers does the skin have