Geoarchaeological research has identified origin sources of bitumen used by the great Olmec civilization of the tropical lowlands of central America, 3000 years ago. The project, described by Olmec scholar David Grove as a “break-though in source analyzing bitumen in Mesoamerica”, may shed light on the vast trade networks throughout prehistoric North America.
Historic and Prehistoric Uses of Bitumen
Bitumen is a black, oily, viscous material that is a naturally-occurring organic byproduct of decomposed organic materials. Also known as asphalt or tar, bitumen was mixed with other materials throughout prehistory and throughout the world for use as a sealant, adhesive, building mortar, incense, and decorative application on pots, buildings, or human skin.
Archaeologists have been investigating the sources of bitumen, that is to say, from whence came bitumen used in ancient settlements, since the 1980s, beginning with materials from archaeological sites in Egypt and Mesopotamia. For example, during the late Uruk and Chalcolithic periods at the Anatolian site of Hacinebi Tepe in present-day Turkey, bitumen was used for construction of buildings and water proofing of reed boats, among other uses. The analysis of the bitumen provided information concerning trade networks throughout Mesopotamia and the near east.
However, studies of bitumen sourcing have not been conducted in the Americas until recently, when researchers Carl Wendt and Shan-Tan Lu compared the geochemistry of several bitumen seeps on the gulf coast of Mexico to samples taken from archaeological sites dated to the Olmec period. Preliminary results from their investigations are reported in the January 2006 issue of the Journal of Archaeological Science.
Olmec Civilization and Bitumen
The Olmec civilization is the name given to a sophisticated culture of the tropical lowlands of the gulf coast central America between about 1200 and 400 BC. They are known for large monumental stone architecture, including massive stone heads, which were likely portrait sculptures of rulers. There are three known major centers to the Olmec civilization, spaced fairly equidistantly from one another: La Venta, San Lorenzo, and the less well known Laguna de los Cerros. Just how these three major cities interacted with one another has been a topic of great interest to archaeologists, since each center had access to different resources, resources which are found archaeologically at all three centers.
The Olmec were also users of bitumen, as were many of the Mesoamerican cultures, as an adhesive and decorative material. One fairly important use of bitumen to the Olmec was as waterproofing for canoes, which would have supported the vast Olmec trade network. The oldest archaeological bitumen (i.e., mixed with other materials) in Mesoamerica so far was recovered from the Olmec sites of San Lorenzo and el Manati. Seeps of natural bitumen occur along the coastal floodplains of the Gulf of Mexico; but archaeological bitumen has been found at sites far into the Mexican highlands, so it has been known for a long time as a likely trade item.
Results of the Research
Wendt and Lu examined the chemical component of ten natural sources (seeps and beach deposits), and 15 archaeological sources from eight early preClassic sites. The data revealed some patterns suggesting similar use of seeps by groups of Olmec sites, supporting the notion of a network of trading/resource procurement. Whether or not this can be used to resolve the ongoing debate about the trade relationships with the societies away from the coast is still a question. Other artifact types used for that have included obsidian and ceramics; bitumen is a more utilitarian and less elite item, and thus has the potential to assist with understanding the basic workings of these networks.
The research by Wendt and Lu is exciting, in that there is great potential to track the extended network of trade by the Olmec, and indeed the network established by all the prehistoric Mesoamerican societies that used this versatile, sticky treasure. In the words of Olmec scholar David Grove, "the future potential represented by Wendt's ground-breaking initial research is magnificent."
Sources
This glossary entry is a part of the About.com Guide to the Olmec Civilization, and part of the Dictionary of Archaeology.
Wendt, Carl J. and Ann Cyphers 2008 How the Olmec used bitumen in ancient Mesoamerica. Journal of Anthropological Archaeology 27(2):175-191.
Wendt, Carl J. and Shan-Tan Lu. 2006. Sourcing archaeological bitumen in the Olmec Region. Journal of Archaeological Science 31:89-97.
Thanks to Carl Wendt for his kind assistance on this report; any errors are the responsibility of Kris Hirst.
