For centuries, historians have debated what caused the Roman
Empire to fall. Entire theories of political and cultural
development have grown from speculation over why the world's
strongest empire collapsed from within. In the 1980s, attention
turned to a new suspect: lead poisoning. The Roman elites
flavored their food and wine with syrups cooked in iron pots.
They were prone to gout, which is a sign of lead poisoning.
Other symptoms of lead exposure include mental retardation,
impaired judgment and erratic behavior. Among those afflicted
were the erratic emperors Claudius, Caligula and Nero. Now, for
today's example: For decades, experts have debated the sharp
rise of violent crime in America in the 1980s and the surprising
fall in crime in the 1990s, a decline that continues today.
Theories abound: The rise in crime has been blamed on the
permissive values of the 1960s, the persistence of poverty and
racism, the spread of drugs, guns and violent video games. The
fall in crime has been credited to the "brok