People have been chewing naturally gummy substances since earliest times. The ancient Greeks chewed resin from the mastic tree, and the Maya of Central America chewed chicle, the latex sap of the wild sapodilla tree. The North American Indians chewed spruce tree sap and taught the New England colonists to do the same. In the mid-1800s, sweetened paraffin replaced spruce resin as the preferred substance for chewing gum. Chicle, the base for chewing gum, is presumed to have been brought to the United States by the Mexican general Antonio López de Santa Anna (1794-1876) in the 1860s. When he returned to Mexico, the general left a chunk of chicle behind with an acquaintance, inventor Thomas Adams, Sr. Adams experimented with uses for the chicle; while it did not make a good rubber substitute, Adams found that it did make an excellent chewing gum...