David Eltis has observed that "in terms of immigration, America was an extension of Africa rather than Europe until late in the 19th century." The unwilling African immigrants were not spread evenly across the Americas; the overwhelming majority arrived in tropical and subtropical "plantation America" with the result that the disease and nutritional environments of this region also became extensions of Africa. While the implications of disease ecology for world history have been examined, and the details of the "Colombian exchange" of plants and pathogens between Europe and the Americas studied, we have no comparable study of the "African exchange." The essays in this volume form the cutting edge of biohistorical research that promises to rewrite the story of humankind's past in significant ways.