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1971 British engineer Godfrey Hounsfield invents the computerized tomography scanner (CAT scan), which builds a 3-D image of the brain
1972 U.S. bans DDT because of its adverse effects on the environment
1974 Farmers discover an army of life-size terra-cotta human figures in a 3rd century B.C. Chinese emperor's tomb near Xian
1974 Arthur Laffer formulates his supply-side economic theories, which hold that reducing federal taxes spurs economic growth and, eventually, increases federal revenues
1974 In Hadar, Ethiopia, Donald Johanson and colleagues find a 3.2 million-year-old skeleton of a new human ancestor, later called Australopithecus afarensis; it is nicknamed Lucy
1975 Scientists discover a natural opiate, now known as an endorphin (endogenous morphine), in the brain
1976 The first supersonic commercial airplane, the Concorde, goes into service
1977 An unusual incidence of childhood arthritis in Lyme, Conn., leads a group of Yale physicians to identify a new bacterial disease transmitted by ticks
1977 Deep-sea vents are found near the Galapagos Islands. The hot, sulfurous water around the vents supports new species of bacteria and sea life
1977 Doctors use balloon angioplasty to unclog a coronary artery
1978 Louise Brown, the world's first test-tube baby, is born in England
1978 To protect Earth's ozone layer, the U.S. bans chlorofluorocarbons, which are used as propellants
1980
1980 Luis and Walter Alvarez speculate that an asteroid's crashing into Earth 65 million years ago wiped out the dinosaurs and other species. In 1991 the putative impact crater is found beneath Mexico's Yucatan peninsula
1980 The World Health Organization declares that smallpox has been eradicated
1981 Inaugural flight of America's space shuttle
1981 Doctors in Los Angeles alert the Centers for Disease Control to five cases of Pneumocystis carinii pneumonia in gay men, one of the earliest signs of the AIDS epidemic
1982 The U.S. Food and Drug Administration approves the first genetically engineered drug: bacteria-produced insulin for diabetics
1982 Surgeons at the University of Utah Medical Center, led by William DeVries, replace Barney Clark's failing heart with a mechanical one designed by Robert Jarvik; Clark dies 112 days later
1984 Alec Jeffreys and colleagues at the University of Leicester, England, develop "genetic fingerprinting," which uses unique sequences of DNA to identify individuals
1985 Robert Gallo, of the U.S. National Cancer Institute, and Luc Montagnier, of France's Pasteur Institute, each publish the genetic sequence of the AIDS virus. The two are identical
1985 French and American oceanographers find the Titanic at a depth of nearly 13,000 ft. in the Atlantic
1986 The U.S. space shuttle Challenger explodes 73 sec. after lift-off
1986 An explosion at an aging nuclear reactor in Chernobyl, Ukraine, releases radiation into the atmosphere
1987 The U.S. Food and Drug Administration approves the antidepressant Prozac
1988 A Brief History of Time, by British physicist Stephen Hawking, becomes a surprise best seller
1988 Harvard receives the first patent for a genetically engineered animal