According to 1491, as many as 90 million people lived in the Western Hemisphere before the arrival of Columbus. The vast majority of these people died from diseases brought from Europe by the various explorers, traders and conquerors who visited North, Central and South America starting in 1492.

Taking into account recent research, Mann argues that Indian societies were larger, older, more complex and more technologically sophisticated than previously believed. They also had much more effect on the environment, building major cities and transforming much of the countryside for agricultural purposes (even the Amazon basin). The Indians of the Western Hemisphere did not “live lightly on the land”.

In fact, according to Mann, the New World that European settlers eventually encountered, with its dense forests, huge herds of bison and vast flocks of passenger pigeons, was a recent development. The catastrophic effects of disease on Indian populations resulted in certain parts of nature running wild, certain species experiencing explosive growth after the Indians could no longer manage their environment, as they had done for thousands of years before Columbus.  (3/15/11)