I'm going to post the link on some History and Archy forums I frequent to see what the consensus of opinion is.
From my initial read, I found this article was pretty much devoid of PC, environmentalist or socialist propaganda. There are many interpretations of data collected over centuries, including the eyewitness accounts from history. It seems to assume that the accounts by de Soto, la Salle and others were correct - and tries to figure out why the changes took place.
I pretty much agree with the article and also the large number of people claimed. I've seen an aerial (partial) view of this Amazon region and the channels and 'mounds' go on for hundreds and hundreds of miles. One person (forgot who, when asked) said that it would have taken 50-100 million people (also forgot the time frame) to 'build' all that was visible in this Amazon region. I believe that the South American civilizations is/are the source of the legends of Atlantis. Solon was told (by the Egyptian high priests) that powers across the Atlantic conquered all the countries in the Mediterranean area in prehistoric times. That would have taken a very large population base to accomplish. (If true?)