Between 400 and 350 BCE, population in the eastern half of the Olmec was slowly diminishing and is still wondered upon how the eventual extinction became.
The Olmec were definitely polytheistic, considering they worshiped a variety of different elemental jaguar gods that looked as if they were mixed with men. {Dubbed as Were-Jaguar.}
Very little is known about the Olmec social hierarchy, however it is said that the large head statues were most likely made for the leaders that have ruled before.
Olmecs practiced basic agriculture using the "slash-and-burn" technique, in which overgrown plots of land are burned, clearing them for planting the ashes that act as fertilizer. They planted squash, beans, manioc, sweet potatoes and tomatoes frequently.
Basically, the Olmec developed and studied subjects such as the concept of zero, linear time, and gravity. This brought them to put attention to these concepts and figure out many assumptions.
Nobody truly knows where or how the Olmec disappeared, but many believe it was the violent droughts that eventually killed their crops, and provided issue for enduring harsh circumstances.