Both men and women have hair on their bodies, sometimes more, sometimes less, sometimes lighter, sometimes darker. Except on the mucous membranes, lips, soles of the hands and feet, they sprout happily until they fall out or are cut off.
Hair grows back unless you are prone to baldness, which is genetically inherited and causes problems for men in particular due to age.
But women can also be affected by this, or go through phases in which they have increased hair loss, e.g. after pregnancy.
Prehistoric man was still covered with a thick coat that protected him from wind and weather. Research has not yet been able to fully solve the mystery of the loss of this splendour of hair; it is assumed that it is connected with the increased sweat formation in humans, because with a strong growth of hair, the sweat evaporates only slowly.
Hair is actually dead cell material, cornea, like fingernails and toenails. Today, hair has a strongly socially oriented function; we use it to determine factors such as beauty, attractiveness and well-groomedness. Hairdressing is practised in some form or another all over the world and hairstyles can sometimes even become status symbols, or at least belong to and characterise the personality.
Whether a person has curly or straight hair depends first and foremost on their genetic make-up. For the hair itself, the rounder the cross-section, the smoother the hair. Conversely, the curlier or curlier the hair, the more elliptical the cross-section of a hair. The most extreme shape is found in black Africans, smooth hair is found especially among Asians. The cross-section is determined by the keratinisation process of the hair as it emerges from the skin, at the base of the hair follicle, which forms the horn particles into hair.
But not only the shape plays a role, but also the building materials of the hair, the proteins. In the course of a person's life, these can change, so the tendency to have curly or straight hair can also change. This is determined by the so-called alpha-helix structures, whose occurrence in the hair is decisive.
Melanins, which can be thought of as colour pigments, are responsible for hair colour. They come in two main shades, the black-brown pigment for dark hair, eumlamine, and the red pigment for blond and red shades, phaeomelanin. Their proportions in the hair make up the colour.
Hair turns grey when less melanin is produced and instead air is absorbed by the hair root. Grey hair is undesirable and unattractive, at least in fashion-conscious circles, where it is systematically combated and covered up with colouring, and increasingly so in men.
Chemical agents can intentionally change the hair structure, this happens for example with perms and through other hair care products.
