In the depths of Genovesa Cave, situated on Mallorca, the premier island of the Balearic Archipelago and the sixth largest landmass in the Mediterranean Sea, archaeologists have unearthed an ancient, submerged stone bridge. This remarkable discovery strongly suggests human inhabitation of the western Mediterranean region significantly earlier than previously posited.
The 5,600-year-old submerged stone bridge in Genovesa Cave, Mallorca, Spain. Image credit: R. Landreth.
The intricate process of reconstructing the initial human colonization of the Balearic Islands in the western Mediterranean has been severely hampered by a scarcity of available archaeological evidence.
Through meticulous examination of a submerged bridge, measuring 7.7 meters (25 feet) in length, Professor Bogdan Onac from the University of South Florida, alongside his esteemed colleagues, has furnished substantial evidence pointing to earlier human endeavors within Genovesa Cave.
“The existence of this submerged bridge, along with other recovered artifacts, unequivocally points to a sophisticated level of human activity. It implies that the earliest inhabitants recognized the cave’s crucial water resources and strategically engineered pathways to navigate its interior,” stated Professor Onac.
Genovesa Cave, positioned in proximity to Mallorca’s coastline, features passages that are now inundated due to elevated sea levels. Distinctive calcite formations, known as speleothems, have developed during periods of elevated sea levels.
These geological formations, in conjunction with a discernible lighter-colored band present on the submerged bridge, serve as invaluable proxies for precisely delineating historical fluctuations in sea level and accurately dating the bridge’s construction.
Prior investigations had tentatively proposed human habitation dating back as far as 9,000 years. However, inconsistencies and the suboptimal preservation of radiocarbon-dated materials, such as nearby skeletal remains and pottery fragments, cast considerable doubt upon these earlier assertions.
More recent scholarly pursuits have leveraged charcoal, ash, and bone fragments recovered from the island to construct a revised timeline of human settlement, placing it approximately 4,400 years ago.
This revised chronology now aligns the period of human presence with significant environmental shifts, including the notable extinction event of the endemic goat-antelope, Myotragus balearicus.
By undertaking a detailed analysis of mineral overgrowths on the bridge and the altitudinal placement of a distinctive coloration band, the researchers ascertained that the bridge was ingeniously constructed nearly 6,000 years ago. This finding predates previous estimations by over two millennia, effectively diminishing the temporal discrepancy between settlements in the eastern and western Mediterranean.
“The historical context of the bridge’s construction appears intrinsically linked to a period of rapid Holocene sea-level rise that occurred just before the 6,000-year mark, followed by a brief plateau in sea level, which subsequently led to the inundation of certain upper sections of the cave,” the authors commented.
“According to our established chronology, the ascent of sea levels abated and remained relatively stable for several centuries between 5,964 and 5,359 years ago. It was during this interval that the phenomena referred to as phreatic overgrowths on speleothems (POS) formed within the cave’s subterranean lake, and a conspicuous ‘bathtub ring’ became evident on the bridge structure.”
“The commencement of the bridge’s construction likely took place early within this period, when traversing the shallow, 0.25-meter deep lake necessitated its creation. However, the structural completion must have been achieved prior to 5,600 years ago, at which point the upper portions of the bridge were submerged.”
“The available evidence strongly indicates that early humans meticulously engineered a stone-paved pathway leading to the cave’s water source, alongside a robust bridge. This infrastructure facilitated access to the cave’s sole other dry zone, the Sala d’Entrada, situated beyond the lake’s expanse.”
“The precise motivations underpinning the construction of these elaborate structures within Genovesa Cave remain, at this juncture, a matter of conjecture.”
“Nevertheless, the chronological limitations imposed by the bridge’s submerged depth, when coupled with the similar depths at which POS and the coloration mark are found, lend considerable credence to the hypothesis of an early human presence on the island by 5,600 years ago, with the potential for origins as far back as 6,000 years ago.”
A comprehensive document detailing these groundbreaking discoveries was formally published today in the esteemed scientific journal, Communications Earth & Environment.
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B.P. Onac et al. 2024. Submerged bridge constructed at least 5600 years ago indicates early human arrival in Mallorca, Spain. Commun Earth Environ 5, 457; doi: 10.1038/s43247-024-01584-4
