10,000 years ago the Sahara was a fertile area, allowing fish to migrate across it. This is giving researchers a possible clue to how early humans migrated across the desert.
In their analysis, Drake and his colleagues found evidence that many creatures, including aquatic ones, dispersed across the Sahara recently. For example, 25 North African animal species have populations both north and south of the Sahara with small refuges within the desert, including catfish (Clarias gariepinus), tilapia (Tilapia zillii), jewel cichlid fish (Hemichromis letourneuxi) and freshwater snails such as the red-rimmed melania (Melanoides tuberculata). Indeed, more animals may have once crossed over the Sahara than over the Nile corridor, the researchers said — only nine animal species that occupy the Nile corridor today are also found both north and south of the Sahara.
If fish could have crossed the Sahara, it is hard to imagine that humans didn’t. Analysis of African languages and artifacts suggest that ancient waterways recently affected how humans occupied the Sahara. For instance, speakers of Nilo-Saharan languages once lived across central and southern Sahara, and may have once hunted aquatic creatures with barbed bone points and fish hooks. In addition, ancient lake sediments suggest the Sahara was green roughly 125,000 years ago, back when anatomically modern humans might have begun migrating out of Africa.
Future work could focus on when species got across the Sahara — genetic analysis of fish could help pinpoint such times in fish, Drake said. However, further research into the past of the Sahara could prove difficult and even dangerous, he noted. Some of the Saharan countries the researchers would like to visit in order to analyze the genetics of fish populations or date the ages of ancient shorelines “are deemed to be too dangerous to visit due to terrorist activity or civil war,” Drake said.