The study provides critical new insights into the African Humid Period, a time between 14,500 and 5,000 years ago when the Sahara desert was a green savanna, rich in water bodies that facilitated human habitation and the spread of pastoralism. Later aridification turned this region into the world's largest desert. Due to the extreme aridity of the region today, DNA preservation is poor, making this pioneering ancient DNA study all the more significant.
Genomic analyses reveal that the ancestry of the Takarkori rock shelter individuals primarily derives from a North African lineage that diverged from sub-Saharan African populations at about the same time as the modern human lineages that spread outside of Africa around 50,000 years ago. The newly described lineage remained isolated, revealing deep genetic continuity in North Africa during the late Ice Age. While this lineage no longer exists in unadmixed form, this ancestry is still a central genetic component of present-day North African people, highlighting their unique heritage.
North Africa remained genetically isolated
Furthermore, these individuals share close genetic ties with 15,000-year-old foragers that lived during the Ice Age in Taforalt Cave, Morocco, associated with the Iberomaurusian lithic industry that predates the African Humid Period. Notably, both groups are equally distant from sub-Saharan African lineages, indicating that despite the Sahara's greening, gene flow between sub-Saharan and North African populations remained limited during the African Humid Period, contrary to previous suggestions.
The study also sheds light on Neandertal ancestry, showing that the Takarkori individuals have ten-fold less Neandertal DNA than people outside Africa, but more than contemporary sub-Saharan Africans. "Our findings suggest that while early North African populations were largely isolated, they received traces of Neandertal DNA due to gene flow from outside Africa," said senior author Johannes Krause, director at the Max Planck Institute for Evolutionary Anthropology.
The spread of pastoralism in the Green Sahara
"Our research challenges previous assumptions about North African population history and highlights the existence of a deeply rooted and long-isolated genetic lineage," said first author Nada Salem from the Max Planck Institute for Evolutionary Anthropology. "This discovery reveals how pastoralism spread across the Green Sahara, likely through cultural exchange rather than large-scale migration."
"The study highlights the importance of ancient DNA for reconstructing human history in regions like Central Northern Africa, providing independent support to archaeological hypotheses," said senior author David Caramelli from the University of Florence. "By shedding light on the Sahara's deep past, we aim to increase our knowledge of human migrations, adaptations, and cultural evolution in this key region," added senior author Savino di Lernia from Sapienza University in Rome.
