Comment by steve_adams_86

You'd be surprised but the "landraces" e.g. historic geographically constrained cultivars tend to do better than modern cultivars in certain geographical regions. A modern even GMO cultivar might have a couple of beneficial traits introduced over the course of a few decades of work. Whereas a landrace might have been selected for yield in that area for a thousand years or more, maybe 100x or more as many generations under selection. As such there is a huge interest among a subset of biologists today to catalog all of these remaining landrace crops and the genetic diversity they contain before they are lost, either due to changing climate wiping out their native environment or the modern farmer replacing these cultivars with ones you can buy in bulk quantities from your seed supplier and have more of an export market (some landrace crops aren't fit for export shipping due to fragility of the crop unlike more modern cultivars; bananas are a good example where there are 1000 types grown but only 1 single varietal particularly fit for overseas shipping hits the supermarket).

Corn is grown in the UP with current varieties currently. It’s not commercially viable because the yields are too low to compete with southern mega yield growers in a highly connected market with efficient transportation systems. There isn’t anything fundamentally hard about growing lower yield corn crops at that location though.

It didn’t necessarily need to be highly productive, just more productive than cultivating local stuff, and even if the corn was not necessarily at its most productive it might have been worth it (and with no real replacement) as part of the companion garden, getting just a few ears of corn would still have been worth more than unproductive wooden stakes.

Or, they had far advanced knowledge of working and remediating soil to grow food. Peat mosses, charcoal, household compost, are all valid soil additives that we now have scientific knowledge to explain how those benefit soil, but they were practicing it in soil that is otherwise unproductive. Given that no one else farmed it in that time it seems that knowledge was lost, but lines up with regenerative agriculture practices we see today.

> Or could there have been warmer micro climates?

Microclimates? The whole world was warmer. Remember when the Vikings settled Greenland? That was 1000 years ago.