World Trade and Biological Exchanges Before 1492, Revised and Expanded Edition postulates that 127 tropical and subtropical plants and animals were transported across oceans to and from tropical continents by early tropical mariners. This volume summarizes our research, opening up new avenues of research and challenging the current ideas of how species were dispersed across the world oceans. A plant, especially a domesticated one, cannot evolve twice on two opposite continents; they require a native wild DNA source. It takes finite time for the species to spread. Eighty-four tropical plants were transported from America to the tropical or subtropical Old World used now by us. The early mariners selected crops from highlands and shorelines, wet and dry climates, took them to the Old World, and apparently planted them in the appropriate ecological locations as this is where the remains were found. So far only the remains of 13 plants show travel from Old World locations to America, although that number will likely change with further research. The sailing that maintained medicinal plants in Egypt and Peru during two separate 1,400 year periods implies continual maritime trade. The most ancient exchanges by mariners were two species of hookworms originating from Southeast Asia. The oldest examples of these parasites were found in mummies in interior Brazil but not in North America. This indicates that diffusion across the oceans of various types occurred that brought these parasites to Brazil over 7,000 years ago. This research will allow scientists and teachers to openly reassess their current notions of the history of civilization and the interaction between civilizations and peoples in ancient times across the oceans.