A. (1)It was not until after World War II that most Southerners felt the impact of air conditioning. (2)As one historian on the subject commented, “The air conditioner came to the South in a series of waves, and only with the wave of the 1950s was the region truly engulfed.” (3)Gradually air conditioning spread to department stores, banks, government buildings, hospitals, schools, and finally, homes and automobiles. (4)Home air conditioning soared after the introduction in 1951 of an inexpensive, efficient window unit. (5)By 1960, 18 percent of all Southern homes had either window units or central air conditioning. (6)That number topped 50 percent in 1970 and almost 75 percent by 1980. (7)“The South of the 1970s could claim air-conditioned shopping malls, domed stadiums, dugouts, greenhouses, grain elevators, chicken coops, aircraft hangers, crane cabs, off-shore oil rigs, cattle barns, steel mills, and drive-in movies and restaurants,” wrote one historian.

B. (1)Americans have long believed in the attainability of a just social and political order. (2)But at no time was the spirit of a just society stronger than during the 1820s, 1830s, and 1840s, when literally hundreds of utopian communities were created. (3)Shaker communities were one of the earliest utopian “experiments.” (4)Aspiring to live like the early Christians, Shakers adopted communal ownership of property and a way of life emphasizing simplicity. (5)Dress was kept simple and uniform; architecture and furniture were devoid of ornament. (6)Robert Owen’s experimental community at New Harmony presented a striking contrast to the Shaker colonies. (7)Owen sought to establish common ownership of property and abolish religion. (8)At New Harmony the marriage ceremony was reduced to a single sentence, and children were raised outside of their natural parents’ homes. (9)Another utopian experiment was perhaps the most notorious and successful—John Humphrey Noyes’s Oneida Community. (10)Noyes established perfectionist communities that practiced communal ownership of property and “complex marriage.” (11)Complex marriage meant that every member of the community was married to every member of the opposite sex. (12)The community also conducted experiments in eugenics—the selective control of mating in order to improve the hereditary qualities of children.

C. (1)Famous poets and writers have claimed for centuries that love stems from powerful emotions. (2)However, research has shown that feelings of love are at least in part influenced by various chemicals in the brain. (3)One group of chemicals that is just beginning to be understood is the pheromones—substances that promote sexual attraction in the opposite sex. (4)Experiments show that males release a chemical in their sweat that has been shown to be highly appealing to women—particularly during ovulation. (5)Similarly, women produce their own pheromones that draw men’s interest—one actually can raise the level of testosterone in a man’s bloodstream.(6)In addition to pheromones, another chemical, phenylethylamine (PEA), plays a crucial role in helping people fall “in love.” (7)Related closely to the addictive stimulant drugs called amphetamines, PEA actually causes people to feel a high from their relationship. (8)The “heart-throbbing” sensations new lovers describe and the feelings of excitement and infatuation that are part of new relationships are directly attributed to this chemical. (9)As with many addictive drugs, eventually the body builds up a tolerance to PEA and the strong feelings begin to wear off, usually within two years. (10)This explains why infatuation cannot last forever.(11)A third group of chemicals—endorphins—appears to be at work in long-term relationships. (12)Endorphins are the body’s natural pain relievers. (13)In addition, they produce a sense of security, tranquility, and calm. (14)During physical intimacy, endorphins are released into the bloodstream, creating the feeling of satisfaction and security common to long-term successful relationships.