The evidence for collapsing agriculture in the Amazon basin a couple of centuries before Columbus hints at disease spreading from contact there, such as from a (historically attested, well equipped) African expedition in 1311 that might not have returned.
The Amazon has proof positive of tree domestication 10000 years ago. The coincidence of collapse right about then seems hard to account for without contact. But we may never know.
The Amazon has proof positive of tree domestication 10000 years ago. The coincidence of collapse right about then seems hard to account for without contact. But we may never know.