Olmec colossal heads by Matthew Stirling in 1938 spurred the first archaeological investigations of Olmec culture. Seventeen confirmed examples are known from four sites within the Olmec heartland on the Gulf Coast of Mexico. Most colossal heads were sculpted from spherical boulders but two from San Lorenzo Tenochtitlán were re-carved from massive stone thrones. An additional monument, at Takalik Abaj in Guatemala, is a throne that may have been carved from a colossal head. This is the only known example from outside the Olmec heartland. Dating the monuments remains difficult because of the movement of many from their original contexts prior to archaeological
Mayan languages is the "Macro-Mayan" hypothesis, which posits links between Mayan, the Mixe–Zoque languages and the Totonacan languages, but more research is needed to support or disprove this hypothesis. In 2015, Campbell noted that recent evidence presented by David Mora-Marin makes the case for a relationship between Mayan and Mixe-Zoquean languages "much more plausible". The Mayan family consists of thirty languages. Typically, these languages are grouped into 5-6 major subgroups (Yucatean, Huastecan, Ch'olan-Tseltalan, Q'anjob'alan, Mamean, and K'ichean). The Mayan language family is extremely well documented, and its internal genealogical classification scheme is widely accepted and established, except for some minor unresolved differences.