Indigenous Amazonian potteries as early reinforced ceramics
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HISTORICAL NOTE
Indigenous Amazonian potteries as early reinforced ceramics By Hortense Le Ferrand
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family of Demospongiae—are found as spiky stacks attached to trees, rocks, or grass, waiting for the next flood to spread their gemmules, clusters of embryonic cells. The skeleton of these animals is comprised of microscopic spicules, needle-like structures made of 80–90% amorphous silica, with the remaining composed essentially of aluminum and iron, with traces of numerous other elements that the sponges filter from the water. The remains of decomposed bodies of these sponges further enrich the soil of the floodplains with their mineral spicules. Around 2000 years bc, indigenous potters prepared ceramic vessels by mixing raw clay extracted from the floodplain with water and other temper materials. Sand, ashes from wood or bones, crushed old potteries (grog), crushed sponges, and rocks were among the many additives that facilitated the construction of the vessel and improved the resistance to breaking of the pots. Once the mixture was prepared, water was removed to obtain a malleable solid paste, and all air bubbles were ejected by a succession of slapping, pressing, and turning. They shaped the paste into a rough coil or long rectangle to start building the structure. Coils were stacked while the potters used their fingers to maintain a constant thickness and to erase the interfaces between the coils. The presence of spicules from the z I sponges’ skeletons x provided plasticity to y the clay as it aligned during the elongation Three-dimensional tomographic reconstruction of potsherds (inset) of the coils, whereas using synchrotron x-rays showing aligned freshwater sponges’ spicules. Photo courtesy of Filipe Natalio. the other tempers hen the Ice Age ended about 12,000 years ago, nomadic foragers began to settle into large villages in prosperous areas around rivers and lakes, domesticating animals and developing agriculture. A few hundred years later, the age of pottery began, providing materials for use with food and crops, as trading goods, and for religious utensils. Each village and local culture developed its own pottery style, with unique combinations of forms, engravings, and colors reflecting mythological narratives and local traditions. Along the Amazon River in the South American tropical rainforest, indigenous people lived in symbiosis with the environment and made large, rounded ceramic vessels directly from the soil of their settlements. In the floodplains of the Urubu River, upstream of the Amazon, the acidic blackwater deposits, resulting from decaying vegetation, have particularly high amounts of aluminum and iron ions, two elements essential for potteries. In this region, the multicellular freshwater sponges Drulia uruguayensis—a
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provided more solidity to prevent the collapse of the structure during mounting. If the humidity of the tropical rainforest reached 100%, the high temperature of the air and of the hands of the potters could slowly dry the pottery, requiring the addition of water
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