Hair is a protein filament that grows from follicles in the dermis. It is one of the most distinctive features of mammals. It serves a variety of functions, including thermal regulation and camouflage; it can be used for communication or as a mating signal; and it can help prevent injury in some animals by eliciting a recoil response from predators.
Hair is composed of three layers: The medulla, the cortex, and the cuticle. The medulla contains the pigment melanocytes that determine hair color, and the cortex is rich in lipids that give it its sheen. The outermost layer is the cuticle, which protects and insulates the hair from water, fungus, and ultraviolet radiation.
Many different hair types are known, and most are the result of genetic mutations or environmental influences. For example, some people have curly hair due to a dominant gene, while others have straight hair because of a recessive gene. Hair may also be thick or thin, coarse or fine, long or short, or a combination of these traits.
The primary function of hair is to insulate the body from cold weather. It also helps regulate the internal temperature by allowing sweat to evaporate, which cools the head and lower body. Hair can also act as a buffer against UV radiation, although it is not as effective as skin. Hair is also a means of social signaling; it can indicate sexual maturity in females and fertility in males.
In addition to its functional role, hair is a valuable aesthetic feature. It can be worn in a variety of styles, such as a ponytail, braid, or bob. It can even be used to sculpt facial features, as in a beard or mustache. The color, length, and thickness of hair is a reflection of cultural, ethnic, and genetic identity.
For many cultures, hair is a source of pride and a sign of beauty and health. It can be a symbol of masculinity and femininity, as well as wealth and status. Many religious and cultural groups have rules about the length, style, or color of hair. These rules can vary between individuals within a culture and may change over time.
Hair damage is common with heat styling, and it can cause brittle or frizzy hair. A good way to reduce this damage is to use a heat protectant before blow-drying or using any other type of heat tool on your hair. There are a variety of heat protectants on the market, and some are more effective than others. Look for products that contain humectants, which are ingredients that attract moisture to the hair shaft and prevent drying. They can be found in most moisturizers and can also be purchased separately. They can help keep the hair hydrated and healthy, which will make it easier to style. They can also keep the hair from becoming damaged by high temperatures, which will improve the quality of your hair over time.