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
Olmec alternative origin speculations Clyde Ahmad Winters have identified the Olmecs with the Mandé people of West Africa. Some researchers claim that the Mesoamerican writing systems are related to African scripts. In the early 19th century, Constantine Samuel Rafinesque proposed that the Maya inscriptions were probably related to the Libyco-Berber writing of Africa. Leo Wiener and others claim that various Olmec and Epi-Olmec symbols are similar to those found in the Vai script (a relatively modern script in Liberia which may have Cherokee influence), in particular, the symbols on the Tuxtla Statuette, Teo Mask, Cascajal Block, and the celts in Offering 4 at La