Did ancient river channels guide humans out of Africa ?
(Africa) 14 October 2008 The first humans to leave Africa didn’t have to struggle over baking sand dunes to find a way out – instead they might have followed a now-buried network of ancient rivers, researchers say. Chemical analysis of snail fossils suggests that monsoon-fed canals criss-crossed what is now the Sahara desert as modern humans first trekked out of Africa. Now only visible with satellite radar (see an image), the channels flowed intermittently from present-day Libya and Chad to the Mediterranean Sea, says Anne Osborne, a geochemist at the University of Bristol, UK, who led the new study. Up to five kilometres wide, the channels would have provided a lush route from East Africa – where modern humans first evolved – to the Middle East, a likely second stop on Homo sapiens’ world tour. Archaeological, genetic and palaeontological evidence have pointed to the Nile River Valley and Red Sea as other potential alleys for human migration out of Africa. Watery clues To make a case
