Amazon cultivation:
As I child I was fascinated by the Amazon jungle. I imagined it as totally wild except for a few villages along the river bank. Beyond that I reckoned that it was much like Florida, only more so, with dense jungle, deep rich soil and lots of exotic animals. I was rather disappointed to learn that the soil is not very rich. It certainly is in the Florida jungles I used to play in. I would return home black with filth. Where there was water, and it seemed most of the landscape was wet, there was exuberant growth.
Well I am not the only one who has been interested. (Jeff Tollefson Footprints in the Forest NATURE vol. 502 no. 7470 October 10, 2013 page 160) Expectations vary. As I child I was once playing with a friend. We were due to meet at a woods. I could not find the place, and later that afternoon he dropped by where my family was staying. When we walked past the place in question I said, “That’s not a woods. That’s a vacant lot.”
“Lots have grass.”
“If it has grass it’s a lawn.”
“A lawn has deep, rich grass and bushes with flowers.”
“That’s a garden.”
“You really don’t know, do you? Well what do you say a woods is?”
“A woods has trees.”
“That’s a forest.”
“In a forest the trees are huge, and they block out the sun.”
“That’s a jungle.”
I was about to say, “You really don’t know, do you?” but he had already used that one, so I had to let it rest.
Predictably then different scientists have different ideas about how many people were running around that jungle and what their state of technology was. In one camp are those who would have sided with my childhood view, minus the rich soil. In the other camp are those who picture an enormous population, capable of sustained agriculture over many years, garden cities with smallish settlements connected by networks of roads, soil that they somehow had groomed so that it remains remarkably fertile to this day, collections of valuable trees. The two camps exchange barbs and some reasonable souls try to find the common ground only to find they are attacked from both sides.
When I first learned about the garden cities I bethought myself that this might be a test for limits on population size and duration. They should, if I am correct, face the same limitations that are so eloquently laid out in the history of southern Mesopotamia. But alas it is not to be for a long time. They did not keep the records we enjoy from Mesopotamia. Perhaps some day there will be sufficient archaeology done so that the time courses of different localities can be understood, but clearly that is not yet the case. And I assure you that the limitations I speak of form no part of the discussion of what has been going on.
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