[mrintegrity]

you mean "large" relative to human populations or large relative to the entire Amazon rain forest? Your sources indicate that there was cultivation widespread around the amazon but not that the /entire/ amazon is as it is due to cultivation. Maybe i misinterpret the intended message of your comment.

[dbspin]

I meant that the Amazon basin and Amazonia are enormous geographic regions. It's highly unlikely that the rainforest itself is the result of cultivation. It does seem to be proven at this point that wide areas were cultivated multiple times in distinct eras of human habitation.