The Arabian Peninsula is more often associated with hot, arid deserts than thriving grasslands and fertile waterways, but new research shows that the peninsula experienced several pulses of increased rainfall over the last 400,000 years. This may have created idyllic conditions and facilitated the spread of early humans into Asia.
The new research establishes northern Arabia as a critical migration pathway in the storied history of our species.
The study builds archaeological fieldwork from Griffith University and Max Planck Institute for Chemical Ecology, in collaboration with researchers from the Saudi Ministry of Culture in the Nefud Desert, which found archaeological sites associated with the remnants of ancient lakes. The materials found at the sites were dated with a method called luminescence dating and were found to to coincide with periods of increased rainfall. Additionally, all of the stone tools found around these long-dry lakes were buried in a distinctive kind of sediment found in fresh water.
These lakes formed when periods of high rainfall brought grasslands and large mammals like elephants and hippos onto the peninsula. The team found that during each ‘Green Arabia’ phase, when higher rainfall transformed the desert region into a lush grassland, early humans began to populate the area, each time bringing a different type of material culture with them.
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Julien Louys, from Griffith University, took part in the excavations and analysed the faunal record at the site.
“Finding large mammal fossils in the middle of this hyper-arid desert was a unique experience,” Louys says. “The most remarkable thing about the fossils was the presence of several fragments of hippo bones. These are currently restricted to wet environments of Africa, but their presence in the Nefud during the last 400,000 years was very definitive proof that the Arabian Peninsula was significantly wetter than it is today.”
Previous research in Southwest Asia has focused on the coastal and woodland margins of the region, but human prehistory in the vast interior has remained poorly understood.
Lead author Huw Groucutt, from the Max Planck Institute, describes the new findings, including the oldest dated evidence for hominins in Arabia at 400,000 years ago, as a “breakthrough in Arabian archaeology”.
‘Green Arabia’ sites were explored by researchers from Griffith University’s Australian Research Centre for Human Evolution contributed to the study, published today in Nature, in collaboration with researchers from the Max Planck Institute for Chemical Ecology.
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