1950s: Bebop is the hip style of music in the big city. Listeners cram into nightclubs to hear the stars of the day improvise.

Today: Live jazz is popular with an older crowd, and disc jockeys, playing everything from hip-hop to drum and bass, have taken over the nightclubs.

1950s: Heroin, a highly addictive opiate, is the most dangerous of the illegal drugs popular with jazz musicians.

Today: Heroin is still in use, although the potential danger to users is considerably greater because of the risks of contracting HIV (Human Immunodeficiency Virus) from shared intravenous needles and because the (street) purity of the drug is greater. According to the 2002 National Survey on Drug Use and Health, 1.6 percent of the United States population aged over twelve has tried heroin at least once.

1950s: In Paris, a group of foreign artists and intellectuals congregate on the...