The researchers dated the colonization of Mallorca based on the dating of underwater rock bridges found in the island’s caves.
In a new paper, the researchers estimate that the 25-foot-long (7.62-meter) bridge is about 6,000 years old, and recent estimates place human settlement at the site back about 4,400 years ago. The team’s study was published today. Communication Earth and the Environment.
“The presence of this underwater bridge and other artifacts indicates a high level of activity and suggests that early settlers were aware of the cave’s water resources and strategically built infrastructure to navigate through them,” Onak said in a University of South Florida release.
Onak said the new dates come from animal bones and pottery found in the back chambers of the Genovesa Cave, on the west side of Mallorca. In a recent paper, the team measured the ages of speleothems growing in the cave, which grow at exactly the same height as sea level. Using these dates, the team was able to precisely reconstruct the water levels in the cave and determine the approximate time when the bridge was built.
The bridge is made of limestone blocks and connects two elevated chambers in the cave, but it’s not the only man-made structure inside the cave: at the entrance to the cave there is also an ancient stone path leading to an underwater lake.
Onak told Gizmodo in a phone interview that water levels in the cave have risen dramatically over the last century and will continue to rise due to climate change and melting glaciers.
The cave’s exact purpose remains unknown — for example, whether it was used for rituals or as a shelter — but the goal of the team’s recent paper wasn’t to interpret its use: They simply wanted to catalog the water levels in the cave over the past 180,000 years or so, which they did.
This study is an interesting case study of how researchers can pinpoint the timeline of human migration. When early modern humans migrated into island environments, they changed the natural conditions around them. Since the only human remains in the cave are poorly preserved pottery, a team of researchers recently came up with the bright idea of ​​dating mineral overgrowths in the cave.
Last week, another team of researchers found that humans may have arrived on a South Pacific island earlier than previously thought, based on dating a resin that was likely processed by humans to be burned as fuel.
