A series of underwater caves off the southern coast of Sicily holds clues about Ice Age-era human migration. A team of ‘citizen scientists’ — including a tugboat captain and both recreational and Italian navy divers — helped discover them.
The findings, reported in PLOS ONE, describe 25 caves and rock shelters that show signs of human occupation from about 17,000 years ago. Many scholars consider Sicily to be among the first islands humans settled in the Mediterranean.
In this case, the researchers were interested in what plants and animals inhabited the island before humans entered, what the geology was like when they arrived, and, possibly, how activities like hunting and foraging could have changed the island’s environment.
“There is a very complicated puzzle here that we are trying to tease out,” says Ilaria Patania, an archeologist at Washington University in St. Louis.
Underwater Caves Reveal Human Migration Patterns
Pinpointing when humans arrived in Sicily is only the first step. “We hope to reconstruct not only the timing of human occupation, but also the environment these people lived in and how they negotiated with natural events like earthquakes, climatic and environmental changes and maybe even volcanic eruptions,” says Patania.
There is still no definitive proof of how humans got to Sicily or from where they came. But this research has opened the possibility of an approach from the south. Earlier work emphasizes human arrival on the island’s north side.
Read More: Searching for Life in Underwater Caves
Traces of Early Settlements in Italy
There’s no definitive proof that early humans sailed from Italy, through the original “rock and a hard place” ancient Greeks called the monsters Scylla and Charybdis — named possibly for volcanoes, whirlpools, or treacherous shoals.
The geology then was very different, with plate tectonics likely tipping the northern section of the island, and lower sea levels making land bridges possible.
“What we see today is not the landscape that humans saw 17,000 years ago,” says Patania.
Back then, the humans probably reached the caves by descending a natural terraced staircase. To enter them now, people need to swim underwater and emerge into chambers above sea level. The caves contain stone tools, pottery, and signs of cooking.
Many of the caves had been discovered earlier, then forgotten about. To relocate them, Patania, who was born in Sicily, tapped into local knowledge. She talked to beachcombers, recreational divers, and even a retired tugboat captain who used to pilot a ship in the area.
Read More: Ice Ages: What Causes the Earth to Freeze Over Every Few Million Years?
Recruiting Citizen Scientists
She showed them what stone tools they might find underwater and asked them to be on the lookout for geologic clues that might indicate human activity. Patania also recruited members of the Italian navy who often dive in the area to clear underwater ordnance left over from World War II.
“We’ve found so many sites that way — just by talking to people,” says Patania. “Without that local knowledge, we would not have accomplished half of the stuff we have accomplished.”
Read More: The World’s Deepest Underwater Cave
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Before joining Discover Magazine, Paul spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
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