The Shatt al-Arab floodplain outside of Basra is marked with thousands of manmade earthen ridges and canals. Archaeologists have long suspected that these may have been part of an ancient agricultural system, but they did not know when or by whom it was built. New research has demonstrated that not only is this theory true, but that the massive infrastructure was dug by a huge labor force of enslaved Africans. The Associated Press reports that researchers identified more than 7,000 features spread across 300 square miles that formed an extensive farming network. Using radiocarbon dating and a technique called optically...