From the swamps to the hills

The consensus has been that teosinte was cultivated along the Balsas about 7000 BC. Then it has gotten vague, until that backwash from the Chibcha 3600 BC. Keith Prufer et al. are delving deeper into the spread of Mesoamerican maize.

I assume Mixe-Zoque for these first farmers.

Agriculture in Mesoamerica, they say, started with squash 8000 BC. Teosinte spread from the Balsas to Panama after 6200 BC and crossed the Darien a millennium later. (That Road To The South was always nasty for us.) At the same (belated) time it reached the Peten, which the paper calls "the Maya lowlands" although I question how Maya the place then was. After 3600 BC some intrepid northern highlanders crossed the now-yummy maize corn with some hardier altiplano breeds, making something that upland peoples (Otomí?) could live off of. This trickled back to southern Mesoamerica where, I understand, were other (relative) highlands as could now farm it. This breed got to South America too.

Except that even the post-Chibchan "Maya" stuck to lowland near-marsh farming of this crop. It took until the second millennium BC before they dared the hills. Overall the impression I get is that wetlands when farmed became non-wetlands, which then had to worry about changes in rainfall. This reminds me of how the lower Iraq suffered from droughts. And indeed the 2100s BC seem drier here as there.

I don't read where the American marshes got salted in Prufer's paper. I just read that they dried out. That was less a worry in the hills which, even if they don't rain, can catch ocean breezes and fogs overnight. The hills instead worry about keeping their soil at all. Indeed, after 900ish BC, I detect terracing: to actively manage erosion through slope stabilization.