"The Olmec were but the first of many societies that arose in Mesoamerica in this epoch. Most had religions that focused on human sacrifice, dark by contemporary standards, but their economic and scientific accomplishments were bright. They invented a dozen different systems of writing, established widespread trade networks, tracked the orbits of the planets, created a 365-day calendar (more accurate than its contemporaries in Europe), and recorded their histories in accordion-folded "books" of fig tree bark paper."