When Spanish explorers ventured to southern Florida in the 16th century, they came across a Native American polity unlike societies they’d seen before. While the people of the Calusa Kingdom tended small gardens, which usually included chili peppers, papaya, and squash, they mainly relied on aquatic resources, they also created their own islands, built from shells and other materials.
Publishing in PLOS One, researchers from the University of Georgia, the University of Florida, Pennsylvania State University, and Florida Gulf Coast University have studied the composition of the kingdom’s capital Mound Key, a manmade 51-hectare island located in Florida’s Estero Bay.
In 2013 and 2014, the research team performed extensive studies on the island, which are comprised of shells, bones, and midden. The island’s tallest mounds are close to 32 feet above sea level, and the researchers postulated that about 1,000 people lived there.
“We focused on several different questions regarding the nature of formation processes at the site, including the nature of midden-mound formation, overall deposition, and site chronology,” the researchers wrote in their study. “To evaluate these issues, we employed coring, excavation, and an extensive radiocarbon dating program.”
After performing radiocarbon dating, the researchers found an odd trend. The deeper they dug, the younger the building materials were.
“It appears that the island was occupied early in its existence, abandoned, and then reoccupied,” the researchers wrote. “During Mound Key’s second occupation, its inhabitants substantially altered the landscape by redepositing old midden to form at least the upper portions of the two largest midden-mounds.”
Study researcher Victor Thompson, an anthropologist with the University of Georgia, suggested that the Calusa abandoned the island when cooler temperatures and low sea levels plagued the area.
Mound Key isn’t the sole evidence scholars have of the Calusa Kingdom. Researchers have also studied Pineland, a town they believe was the second largest when the Spanish arrived. Based on previous research at that site, scholars have learned that the Calusa people lived atop midden-mounds, engineered canals, and created water-storage facilities. This indicates the people engineered their towns to respond to environmental changes, like sea-level rises.
The scientists will return to Mound Key this month to continue their research.
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