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Determining the evolutionary function of androgenic hair must take into account both human evolution and the thermal properties of hair itself. The thermodynamic properties of hair are based on the properties of the keratin strands and amino acids that combine into a 'coiled' structure. This structure lends to many of the properties of hair ...
Qiviut is produced by the muskox's secondary hair follicles, which are not associated with sebaceous glands, and therefore is a much drier fibre than wool, having only about 7 percent oils. The hair follicle density is very high (approximately 42 mm 2 [0.065 sq in]) and qiviut is shed in a tightly synchronized spring moulting period. The qiviut ...
Whereas hair is not so dense. There's less of it." [3] This remains untrue however, because the human head has as the same "follicle density" as a mouse, but it just so happens to be genetically predisposed to stop at the head and not continue down the body. [3] There are three types of hair: ground hair, guard hair, and whiskers. "Ground hair ...
The dissipation of body heat remains the most widely accepted evolutionary explanation for the loss of body hair in early members of the genus Homo, the surviving member of which is modern humans. [7] [8] [9] Less hair, and an increase in sweat glands, made it easier for their bodies to cool when they moved from living in shady forest to open ...
A person's hair and fingernails do not continue to grow after death. Rather, the skin dries and shrinks away from the bases of hairs and nails, giving the appearance of growth. [405] Shaving does not cause terminal hair to grow back thicker or darker. This belief is thought to be due to the fact that hair that has never been cut has a tapered ...
Nylon, the first synthetic fiber in the "fully synthetic" sense of that term, [citation needed] was developed by Wallace Carothers, an American researcher at the chemical firm DuPont in the 1930s. It soon made its debut in the United States as a replacement for silk , just in time for the introduction of rationing during World War II .
Abdominal hair is the hair that grows on the abdomen of humans and non-human mammals, in the region between the pubic area and the thorax (chest). The growth of abdominal hair follows the same pattern on nearly all mammals, vertically from the pubic area upwards and from the thorax downwards to the navel .
Natural materials show a combination of normally contradicting mechanical properties (softness and toughness), due to their hierarchical structures of fibrils across multiple length scales. [7] These fibrils are often oriented in a single direction, leading to anisotropic mechanical response in the resulting biocomposite material. [ 8 ]