A new study finds that Arabia was once a green corridor of rivers and lakes, enabling animal and human migration between Africa and Eurasia over the past 8 million years.
A new study published in Nature reveals that the area now known as the Saharo-Arabian Desert, spanning between Africa and Saudi Arabia, was not always an arid expanse. Over the past 8 million years, this region experienced recurring periods of greenery, featuring rivers and lakes that supported the movement and habitation of animals and early humans.
Led by an international team of researchers and supported by the Saudi Heritage Commission and Ministry of Culture, the study highlights the region’s previously unrecognized role as a key corridor for biogeographic exchange between Africa and Eurasia.
Today, the Saharo-Arabian Desert is one of the world’s largest natural barriers, significantly restricting the dispersal of humans and wildlife between the two continents. Earlier studies had suggested this desert environment had remained largely unchanged for at least 11 million years.
Evidence of a Wetter Past
But Professor Michael Petraglia, Director of Griffith University’s Australian Research Centre for Human Evolution and co-author on the new study, said fossil evidence from the Late Miocene (marked by an increase in global temperatures) and Pleistocene (which contained multiple ice ages) suggested the episodic presence within the Saharo-Arabian Desert interior of water-dependent animals.
Animals such as crocodiles, equids, hippopotamids, proboscideans, were likely sustained by rivers and lakes that were largely absent from today’s arid landscape.
“These wetter conditions likely facilitated these mammalian dispersals between Africa and Eurasia, with Arabia acting as a key crossroads for continental-scale biogeographic exchanges,” Professor Petraglia said.
Speleothems and Shifting Climates
Dr. Monika Markowska of Northumbria University, UK, and Dr. Hubert Vonhof of the Max Planck Institute for Chemistry, Germany, conducted new work on cave speleothems (mineral deposits such as stalactites and stalagmites) that led to the realization that there were numerous humid phases in Arabia during the last 8 million years.
Dr. Markowska, who was lead author on the study, explained that little was known about Arabia’s palaeoclimate before this time, noting: “The findings highlighted that precipitation during humid intervals decreased and became more variable over time, as the monsoon’s influence weakened, coinciding with enhanced Northern Hemisphere polar ice cover during the Pleistocene.”
Dr. Faisal al-Jibrin, lead Saudi archaeologist of the Heritage Commission, said “Arabia has traditionally been overlooked in Africa-Eurasia dispersals, but studies like ours increasingly reveal its central place in mammalian and hominin migrations.”
Reference: “Recurrent humid phases in Arabia over the past 8 million years” by Monika Markowska, Hubert B. Vonhof, Huw S. Groucutt, Paul S. Breeze, Nick Drake, Mathew Stewart, Richard Albert, Eric Andrieux, James Blinkhorn, Nicole Boivin, Alexander Budsky, Richard Clark-Wilson, Dominik Fleitmann, Axel Gerdes, Ashley N. Martin, Alfredo Martínez-García, Samuel L. Nicholson, Gilbert J. Price, Eleanor M. L. Scerri, Denis Scholz, Nils Vanwezer, Michael Weber, Abdullah M. Alsharekh, Abdul Aziz Al Omari, Yahya S. A. Al-Mufarreh, Faisal Al-Jibreen, Mesfer Alqahtani, Mahmoud Al-Shanti, Iyad Zalmout, Michael D. Petraglia and Gerald H. Haug, 9 April 2025, Nature.
DOI: 10.1038/s41586-025-08859-6
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