twovultures
Donor
No American civilizations = hardly any Native Americans anywhere. At all. Period. The physical geography of Americas completely different. As I've been trying to beat into Tyr's head, even the Amazon rainforest and the Great American plains WON'T EXIST, they are human made constructions due to our thousands of years of intervention.
Pump your brakes there son, you are both being rude AND seem to be misunderstanding Mann. In 1491 he doesn't say that the Amazon was created by humans, just changed by them. While parts of the Amazon were made fertile through terra preta agriculture and burnings, there are still large parts of it which don't seem to have been altered this way. The Amazon Rainforest exists because of the huge river, not human interference.
IIRC he does claim that the Great Plains have been shaped by human activity, but it's more complicated than that. While human-made fires have effected the area, the Great Plains are semi-arid grasslands because of their inland location and the effects of weather, not human actions. As Workable Goblin points out, these environments are the result of millions of years of geologic change that started long before humans.
Your PoD would have to be to make the proto-potato and teosinte/proto-maize not exist
They can still exist, it's just that the domestication events that had them used as foodstuffs by humans wouldn't exist (or would be altered).
Without those crops you STILL would have those large civilizations and large cities in the Amazon.
Without manioc (or yucca, tapioca, cassava, arrowroot or whatever you call it) there will be a lot less calories to be gained from farming in the Amazon area. The wealth of food naturally in the region will probably allow for a relatively large population, but most of this food will be scattered and difficult to get without being nomadic. So we would see less people and less city-like structures.
This is ASB clearly.
Not in my opinion, though like I said it does kind of toe the line.