Word: pigmentation
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Dates: during 1960-1969
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...TIME cover, May 6, 1966), has been primarily concerned with the eye's chemical makeup and reactions. Pursuing a "hunch" in the early 1930s, he discovered the presence of vitamin A in the retina, then went on to determine its presence and complex workings in the visual pigment. Now, he says with undiminished excitement, "we're on the edge of a whole series of new things" in knowledge of the eye, including a better explanation-perhaps eventually even a treatment-for color blindness...
...that usually, though not invariably, characterizes members of the Negroid race may also be a protective device. If man was first born in tropical Africa, as some anthropologists now suggest, then it is possible that his skin, whatever color it may have been to begin with, took on added pigment-again, starting with chance mutation-as a screen against harmful radiation from the sun. It is a fact that Negroes seldom have skin cancer, though its incidence is rising noticeably in the white population of the U.S. The same pigment, by filtering solar radiation, impedes synthesis of vitamin D, which...
...layers of the skin involved in the sun-screening process are visible under a microscope. Below the skin's outermost horny layer, or stratum corneum (see diagram), lies a germinative layer where, on exposure to sunlight, the pigment-producing cells are stimulated to produce more melanin-and a suntan. The black races (Negro, Bushman-Hottentot and Australoid), with a more abundant supply of melanin, are in effect, perpetually tanned. Members of the white race are transparent-skinned in winter, when they must make the most of the limited ultraviolet avail able to synthesize vitamin D, but they take...
...problem is a relatively modern one. Whether out of innate good sense or colonialist snobbery, whites up through the 19th century shunned the tropical sun, carried parasols, wore big-brimmed hats and left exposure to nonwhites, whom nature has kindly endowed with pigment protection. A white man's tan, in fact, is the result of a dark pigment that rises from mid-level layers of the skin in an effort to guard against further assaults by the sun. But such tanning was not thought of in the U.S. as a sign of health until the 1920s, after sunlight...
Wrinkles & Chins. The bone-dry climate of North Africa, however, has preserved almost perfectly the portraits painted at Faiyum, especially those done on wood panels in encaustic (a mixture of beeswax and pigment, usually applied with a cauterium, or hot spatula). Today, these paintings tell historians most of what is known about portrait technique 1,100 years before the Renaissance. Modeling and shading were expertly done. Except that the anonymous workmen of Faiyum customarily enlarged eyes (large pupils being considered at the time a sign of beauty), classical realism was faithful in portraying hair styles, jewelry, wrinkles and occasionally double...