The Sahara Desert, known for its scorching aridity, hides a surprisingly fertile past. For years, scientists have speculated about a green Sahara, but now, recent research sheds light on this enigma.
A detailed analysis of stalagmites in caves in southern Morocco reveals that the region experienced consistent rainfall for millennia.
In parallel, a study of the DNA of two mummified women, found in southwestern Libya, provides a unique glimpse into an isolated North African lineage.
Their genomes, dated to 7,000 years ago, suggest that the “Green Sahara” was a historical reality rather than a mere theory.
Today, it is difficult to imagine the Sahara as a green paradise, when it is synonymous with heat and dryness. However, during the Holocene, North Africa enjoyed more habitable conditions, with savanna landscapes and abundant water.
Morocco reveals a green Sahara
This finding is crucial, as it provides precise dates that describe a period long enough to allow sustained human life and activity. This reconfigures our understanding of the history of settlements and cultural changes in the region.
Stalagmites, formed only when water seeps from the surface, are invaluable witnesses to past climatic conditions.
A team of researchers used uranium and thorium isotopes to date the growth of stalagmites in the southern Atlas, revealing a period of abundant rainfall between 8,700 and 4,300 years ago.
The study of these stalagmites, published in Earth, shows that the southern Atlas, due to its geography descending towards the Sahara, may have facilitated the movement of water, supporting pastoral societies that depended on these conditions for their survival.
Additional research on the oxygen footprint in carbonate (δ18O) indicates that approximately 7,000 years ago, the region experienced episodes of intense rainfall from “tropical plumes.” These rains would have added up to 27 centimeters more annual precipitation at the wet peak.
On the other hand, the genomic analysis conducted at the Takarkori rock shelter in Libya, published in Nature, reveals that the women from 7,000 years ago were Neolithic herders with a unique genetic lineage at the North African level, evidencing prolonged isolation from other African lineages.
This discovery challenges previous assumptions about the population history of North Africa, suggesting that herding spread more through cultural exchange than through massive migrations.
In broader terms, these discoveries offer valuable lessons for current arid regions. Changes in rainfall patterns can transform desert landscapes into fertile habitats and vice versa, directly affecting human life and social organization.
Understanding the drivers behind past rains helps us reconstruct the climate of North Africa and its sensitivity to changes, providing a framework for future research on desert climate.
