However, some people who have early-onset Alzheimer's don't have mutations in these three genes. That suggests that this early-onset form of Alzheimer's disease is linked to other genetic mutations that haven't been identified yet.
Early history Cigars, cigarettes Cancer by the carton Legal history Surgeon General's warning. (CNN) -- Tobacco was first used by the peoples of the pre-Columbian Americas. Native Americans apparently cultivated the plant and smoked it in pipes for medicinal and ceremonial purposes.
Christopher Columbus brought a few tobacco leaves and seeds with him back to Europe, but most Europeans didn't get their first taste of tobacco until the mid-16th century, when adventurers and diplomats like France's Jean Nicot -- for whom nicotine is named -- began to popularize its use.