The Columbian Exchange: Biological and Cultural Consequences of 1492 | Alfred W. Crosby
Thirty years ago, Alfred Crosby published a small work that stressed a simple point - that the most important changes brought on by the voyages of Columbus were not social or political, but biological in nature. This 30th anniversary edition includes a new preface from the author.
The Columbian Exchange: Biological and Cultural Consequences of 1492 | 
