Human hair color

Hair color is the result of pigmentation due to the presence of the chemicals eumelanin and pheomelanin. In general, the more melanin present, the darker the hair color; the less melanin, the lighter the hair color. Black hair predominates outside of Europe. A person's hair color may also change over time and may be more than one color at a time. Considerable differences in color and texture exist between individuals of similar ethnicity, and immigration and global travel have greatly increased the diversity of hair characteristics among many countries.

Hairstyle

For humans, haircut, hairstyle, or hairdo normally describes cutting or styling hair on the top of the head, although it may also refer to the cutting and styling of facial hair.

The Hair is a special arrangement of hard keratin. Keratins are proteins; long chains of amino acids. Unlike other animals, human beings of many cultures cut their hair, rather than letting it grow naturally. Hair styles are often used to signal cultural, social, and ethnic identity and can be used to illustrate social status or individuality. It is a common misconception that men and women have the same hair.

"Biologically, there is a difference in the length of hair between the sexes. If the hair is left uncut, the female usually has the longer of the two. We have no real explanation for this."(from: Hair Structure And Chemistry Simplified, Milady Publishing Corp. 1986)

Adornment of the hair is done for many reasons such as the expression of personality, religious practice, or rank in society. Most hairstyles conform to socio-cultural influences and are gender biased. Fashion trend(s) may have the greatest influence on hair styling today. Different types of hair such as curly, straight, coarse, or fine will dictate the kind of hairstyle one may have. Hair density, texture, and length are all factors that will determine the ability of hair to perform in a certain style. A person will also want to consider face shape, lifestyle, and personal ability when chosing a hairstyle.

Head hair

Head hair is a type of hair that is grown on the head (sometimes referring directly to the scalp). The most noticeable part of human hair is the hair on the head, which can grow longer than on most mammals and is more dense than most hair found elsewhere on the body. The average human head has about 100,000 hair follicles. [1] Its absence is termed alopecia, commonly known as baldness. Anthropologists speculate that the functional significance of long head hair may be adornment, a by-product of secondary natural selection once other somatic hair had been lost. Another possibility is that long head hair is a result of Fisherian runaway sexual selection, where long lustrous hair is a visible marker for a healthy individual (with good nutrition, waist length hair—approximately 1 meter or 39 inches long—would take around 84 months, or about 7 years, to grow). Each follicle can grow about 20 individual hairs in a person's lifetime. [2] Average hair loss is about 100 strands a day. The average human scalp measures approximately 120 square inches (770 cm²). These values are also reported by Desmond Morris[3] although it is not clear if these are applicable to both men and women.

Hair

Hair is a filamentous outgrowth of protein, found only on mammals. It projects from the epidermis, though it grows from hair follicles deep in the dermis. Although many other organisms, especially insects, show filamentous outgrowths, these are not considered "hair". So-called "hairs" (trichomes) are also found on plants. The projections on arthropods, such as insects and spiders are actually insect bristles. The hair of non-human mammal species is commonly referred to as fur. There are varieties of cats, dogs, and mice bred to have little or no visible fur. In some species, hair is absent at certain stages of life.

The primary component of hair fiber is keratin. Keratins are proteins, long chains (polymers) of amino acids.