>>513710930
Yes, the south American civilization that was there was probably a lot larger than we think, we keep finding massive settlements unde the thick jungle.
What probably happened was large cities and road ways were clear cut and then, as suggested once civilization collapsed it quickly got overgrown by the jungle. It doesn't mean the that the Amazon was deliberately planted by humans tho.
As for the monkeys, they aren't that close enough to breed with one another, like European and North American beavers, they've been split up isolated for so long they are just close cousins. Because at one point south America and Africa were a lot closer to one another, even attached, so somewhere down in that hemisphere a common ancestor emerged, and evolved into different types of monkeys, but once the continents started to split, they both went on their own evolutionary path, wit their genetics drifting further and further apart.