The evolution of human skin(?)
Abstract
Since human skin is very different from that of all other known mammals, its evolution has very likely been unique. Human skin, however, shares some characteristics with the skin of other primates: only man and other primates have true dermatoglyphics and Meissner's corpuscles on their palms and soles, nails, instead of claws and hooves and cecrine sweat glands in their hairy skin. The uniqueness of human skin is that it has lost its hair cover but has remained, nonetheless, hairy; the only hair it has lost are the vibrissac. Most of human hair is miniaturized and the skin appears to be naked. All human hair follicles, regardless of size and location are richly innervated and comprise the principal anatomical unit of cutaneous sensibility. Whereas skin pigmentation is a human adaptation to exposure to the hazards of sunlight, cutaneous pigmentation in many other mammals has little relevance to sunlight. Human epidermis, thicker than that of furred mammals, has a conspicious, well-structured undersurface even in hairy skin. This peculiarity is shared with the skin of chimpanzees and gorillas. The abundance of elastic fibers in the dermis of human skin is shared also with chimpanzees and gorillas. Human stamina, bipedal stance and locomotion must have been acquired pari passu with an elaborate cutaneous vascular system and several million eccrine sweat glands which together help dissipate body heat. The sweat glands in the hairy skin and those on the palms and soles have a different phylogeny, ontogeny and physiology. Whereas all non-human primates, including chimpanzees and gorillas, have apocrine glands over the entire body only man and these two great apes have an axillary organ for the production of odor. Human scbaccous glands are large and their secretion may contribute to the overall human odor. Human females are unique among mammals in having enlarged breasts when not lactating; these appendages are likely to be signaling devices for sexual attraction. The sex skin of Old World monkeys and chimpanzees seems to share the properties of the skin of women. The human scalp has a unique structure, but pattern baldness, which to a degree occurs in all human individuals, is a phenomenon that also occurs in a number of primates. This essay points out features in human skin which are also found only in chimpanzees and gorillas. The closeness of human skin to the skin of these two great apes cannot be avoided.
- Publication:
-
Journal of Human Evolution
- Pub Date:
- January 1985
- DOI:
- 10.1016/S0047-2484(85)80090-7
- Bibcode:
- 1985JHumE..14....3M
- Keywords:
-
- skin;
- evolution;
- hair;
- sweat;
- ontogeny;
- vascularity;
- axillary odor;
- sebaceous glands;
- breasts;
- sex skin;
- baldness