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February, 2000: Mesoamerica
The term Mesoamericans is used to describe advanced, pre-Columbian peoples who once lived in the southern section of North America and parts of Central America. These areas, home to the Mayan, Aztec, and Incan civilizations, encompass present-day Mexico, Yucatan, Belize, and Guatemala, with some scholars including the northernmost regions of South America as well. In addition to the other unique accomplishments of these early civilizations, it has now been discovered that the Mesoamericans had learned to make a "modern" product by combining two of their native plants.
A research team at the Massachusetts Institute of Technology (MIT) has unearthed evidence indicating that by 1600 B.C. these civilizations had the knowledge and ability to produce rubber from latex. This was almost 3,500 years before Charles Goodyear invented vulcanization, the process that converts the raw material latex into a usable form of rubber. Vulcanization uses heat and sulfur to transform soft, tacky latex into a strong, temperature-stable, elastic rubber. Untreated by vulcanization, rubber-containing latex is gummy when first tapped and hard and brittle when dry.
Mesoamericans were able to produce a rubber product with diminished surface tackiness and increased tensile strength by mixing together the products from two plants: Castilla elastica and Ipomoea alba. C. elastica is a tree in the Moraceae family of dicots whose members typically contain a milky latex. Their cell walls are impregnated with silica or calcium carbonate, and their flowers tend to be small, since they are wind-pollinated. I. alba is in the Convolvulaceae family, whose members are also dicots and typically lianas, woody, climbing vines. These herbaceous climbers always twine to the right and in these regions are found twined around the trunks of C. elastica.
When ancient Mesoamericans combined latex collected from C. elastica with liquid extracted from I. alba, the two reacted in a way that chemically modified the polymers in the raw latex. The mixture mimicked the process of modern-day vulcanization and resulted in a rubber that was both tough and pliable. The Mesoamericans used the rubber they produced to form many objects: hollow figurines for worship or ornament; rubber bands to attach stones to wooden handles, forming tools such as axes and hammers; paint for the body and for sacred symbols on floors and walls; rubber-soled sandals; and even lip balm!
However, the foremost rubber creations for Mesoamerican societies were rubber balls and the ball games they gave rise to. The balls ranged in size from ping-pong to basketball, depending on the game. The games were often fierce and bloody, sometimes culminating in a post-game human sacrifice. Pedro Martyr, the official historian of the sixteenth-century Spanish courts, documented the games, the incredible bouncing balls, and the tree and vine material that was collected to make the balls. Martyr and other Spanish colonists visiting the New World at that time were certainly taken aback by the brutality of the sport--but they were even more amazed by the bouncing balls. In those days, European ball games were played with balls made of pigskin that certainly did not bounce over a person's head!
As the games became an integral part of Mesoamerican society, the courts progressed from open dirt fields to masonry enclosures with seating for several thousand spectators. In one game, the athletes would hit a rubber ball through hoops without using their hands or feet. Another version used a smaller ball hit with a stick. The games became central to the Mesoamerican cultures because, in addition to providing entertainment for the general public, the team members used the combat within the ball courts to settle disputes and govern land and slave ownership. The games also served as religious outlets and spiritual gatherings. The Mayans, for example, had a version of the ball game called "chaah," which reenacted their creation story. These recreational activities, sporting events, religious channels, and governmental controls would not have been possible without the rubber balls created by C. elastica, I. alba, and the first time they were mixed together.
References, Websites, and Further Reading
Prehistoric polymers: Rubber processing in ancient Mesoamerica. Journal of Science 284 (June 18, 1999): 1988-91.
Stern, Introductory Plant Biology, 8th Edition
Chapter 1: What Is Plant Biology?
Chapter 2: The Nature of Life
Chapter 4: Tissues
Chapter 6: Stems
Chapter 8: Flowers, Fruits, and Seeds
Chapter 11: Growth
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