Science magazine this week details the discovery of a stone block in Veracruz, Mexico, that contains a previously unknown system of writing; believed by archeologists to be the earliest in the Americas. The slab - named the Cascajal block - dates to the early first millennium BCE and has features that indicate it comes from the Olmec civilization of Mesoamerica. One of the archaeologists behind the discovery, Brown University's Stephen D. Houston, said that the block and its ancient script "link the Olmec civilization to literacy, document an unsuspected writing system, and reveal a new complexity to this civilization." "It's...