Short answers, pulled from the story.
The name Olmec literally means rubber people, a title bestowed by the Aztecs two thousand years after the civilization had vanished. This defining label remains the standard term for the first great culture of Mesoamerica despite the Aztecs appearing long after the society disappeared.
This ancient society flourished in the swampy lowlands of modern-day Veracruz and Tabasco from roughly 1200 to 400 BC. Their heartland was defined by the Sierra de los Tuxtlas rising sharply from the Gulf of Mexico and included the Coatzacoalcos river basin.
Seventeen colossal heads have been unearthed to date, ranging in size from the Rancho La Cobata head at 10 feet high to the pair at Tres Zapotes at 14 feet. The largest of these sculptures weigh between 25 and 55 tonnes and were carved from single blocks of volcanic basalt.
The Olmec are credited with the development of a writing system, the invention of the Mesoamerican calendar, and the concept of zero. The Cascajal Block dated between 1100 and 900 BC contains 62 symbols and is hailed as the earliest pre-Columbian writing.
Scholars have yet to determine the cause of the decline, with theories ranging from environmental changes that rendered the region unsuited for large groups of farmers to volcanic eruptions that blanketed the lands. The latest thinking suggests that environmental changes may have been responsible for the shift in Olmec centers, with certain important rivers changing course.
Olmec culture was unknown to historians until the mid-19th century when the Mexican antiquarian traveler José Melgar y Serrano published a description of the first Olmec monument to have been found in situ in 1869. This monument, the colossal head now labeled Tres Zapotes Monument A, had been discovered in the late 1850s by a farm worker clearing forested land on a hacienda in Veracruz.