Great Lakes other lakes as "the lower lakes", because they are farther south. Sailors of bulk freighters transferring cargoes from Lake Superior and northern Lake Michigan and Lake Huron to ports on Lake Erie or Ontario commonly refer to the latter as the lower lakes and Lakes Michigan, Huron, and Superior as the upper lakes. This corresponds to thinking of Lakes Erie and Ontario as "down south" and the others as "up north". Vessels sailing north on Lake Michigan are considered "upbound" even though they are sailing toward its effluent current. Lakes Huron and Michigan are sometimes considered a single lake, called
African Great Lakes "Homo erectus" boy was discovered. More recently, a 3,500,000-year-old skull was discovered there, named "Kenyanthropus platyops", which means "The Flat-Faced Man of Kenya". Fishing—primarily of tilapia species but also of Nile perch—provides the main livelihood. With four Great Lakes on its borders, Uganda ranks as one of the world's largest producers of freshwater fish. The climate and rich volcanic soils in the highlands also sustain intensely cultivated croplands. The economies of the Great Lakes region states have different structures and are at various stages of development. The GDP real growth rate ranges from 5.1 percent in Burundi to 6.4 in