Ancient Humans Built A Bridge Inside A Cave In Spain Nearly 6,000 Years Ago: Study

An ancient bridge submerged within the depths of Genovesa Cave on the Spanish island of Mallorca has unveiled new evidence that suggests humans first settled on the island much earlier than previously believed. The findings, detailed in a study published in the journal Communications Earth & Environment, have provided insights into the timeline of human settlement across the western Mediterranean. Experts believe that this latest discovery could narrow the gap between when humans settled in the eastern and western Mediterranean regions. 

Until now, a lack of written records and limited archaeological evidence made it difficult to piece together the point at which humans colonised and settled on the Mediterranean islands. However, now the discovery of the submerged ancient bridge is helping experts determine when humans first settled on the islands. 

According to the study, a telltale "bathtub ring", along with mineral formations detected on the bridge, has allowed scientists to estimate that the structure was built nearly 6,000 years ago. "The presence of this submerged bridge and other artifacts indicates a sophisticated level of activity, implying that early settlers recognized the cave's water resources and strategically built infrastructure to navigate it," said lead study author Bogdan Onac, a professor in the School of Geosciences at the University of South Florida.

According to the study, the ancient bridge is made of large, heavy limestone blocks, some of which span 4.2 feet across. It still remains unclear what mechanisms enabled ancient humans to build the bridge. However, researchers believe that those who built the bridge wanted a dry, continuous path to connect the cave's entrance with a chamber beyond a lake within the cave. 

The bridge was first discovered in 2000. A few years afterwards, a study estimated the bridge to be 3,500 years old based on pottery funds in one of the cave's chambers. Since then, researchers that radiocarbon-dated bones and pottery from Mallorca suggested a human presence may have been on the island 9,000 years ago. However, after studying ash, bones, charcoal and the rise of sea levels across other islands, experts took a different approach. 

"It was only in the past four years that we finally gathered the data needed to address this longstanding research topic and better estimate the arrival time of humans in Mallorca," Mr Onac said.

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The researchers studied a light-coloured band on the submerged bridge within the cave as well as calcite encrustations that formed on the bridge during times when the sea level was higher and filled the cave. They determined that the bridge was assembled about 6,000 years ago. The colour band matched the same level where mineral deposits formed when the sea level was at a standstill, indicating it must have been constructed earlier than 5,600 years ago, Mr Onac explained. 

The bridge was likely used for 400 to 500 years before rising sea levels caused the cave's lake to cover the bridge, he said. 

The team, however, doesn't have clear evidence on how ancient humans used the cave.