By: Al Cameron Although the Europeans presence in the Americas from 1492 to many years later caused drastic change in the environment, their part in forever altering the entire American ecosystem was minor when compared to the part of the true criminals: the European animals. The introduction of these European animals into the New World had the most destructive effects on the new environment and everlastingly altered the ecology of the Americas. During the time that pre-dated the arrival of the Europeans, the Americas remained basically untouched and prevailed as virgin land. The land was populated with n