Respond to the following quotation from the introduction of the book The Columbian Exchange by Alfred Crosby. “The first step to understanding man is to consider him as a biological entity which has existed on this globe, affecting, and in turn affected by, his fellow organisms, for many thousands of years.”

Source: Alfred W. Crosby. The Columbian Exchange, Biological and Cultural Consequences of 1492. Westport, Connecticut: Praeger Publishers, 2003.

Using your knowledge of world history before 1450, identify and explain 3 examples that support Crosby’s assertion.