The Less You Know: From Einstein to Aniston

In an NBC public service announcement, "Friends" star Jennifer Aniston peeks from beneath her trademark fringe and asks, "Why you should stay in school? Smart is sexier than stupid any day." Clever, huh? Compare it to a 1923 PSA, in which "Betty Boop" creator Max Fleischer animated Einstein's theory of relativity. After that, PSAs regularly addressed social issues of the day, but '80s deregulation, media mergers, and greater competition led to today's network-produced spots, which highlight the actor more than the message. The next generation of boob-tube junkies may know the names of more stars than the editors of People, but will they give a hoot?

1923 Fleischer's short film, shown newsreel-style to American movie audiences, explains Einstein's theory about how light curves around warps in space/time.

1942 The advertising industry's War Advertising Council spends $300 million from 1942 to 1945 to improve the image of big business by supporting the war effort.

1945 Declaring "the war never stopped, only the enemy has changed," the Ad Council launches print and radio campaigns for social issues. Its most enduring creation, Smokey Bear, now has his own Web site and is recognized by nearly 90 percent of Americans.

1950s TV networks begin broadcasting PSAs, many of which decry communism. A threat to America? Maybe. To business and advertisers? Most definitely.

1963 PSAs push social issues, but the Ad Council forgoes running anti-smoking PSAs. The American Cancer Society creates its own spots.

1970s PSAs reach their high-water mark with Chief Iron Eyes Cody, who tugs at heartstrings with his lone tear over litter, and with ABC's animated "Schoolhouse Rock." Created because an ad executive's son could remember Rolling Stones' lyrics but not his multiplication tables, ditties like "I'm Just a Bill" are implanted into the minds of a generation.

1980s Reagan's FCC deregulates the industry, watering down requirements for public affairs programming. "Schoolhouse Rock" dies. Nancy's "Just Say No" mantra is born.

1992-96 Leading a PSA renaissance, young ABC executives revive "Schoolhouse Rock," though with only two spots per Saturday. Meanwhile, NBC's ubiquitous "The More You Know" series highlights its "hot" stars.