[psidebot]

"Grains produce more calories per acre than almost all other foodstuffs." - While this may be true, there are are a couple caveats.

First, the per-acre yields for heritage varietals are much lower than those cited in the article, and I suspect that some crops have improved quite a bit more than others.

Second, I would speculate that grains' biggest advantage in neolithic times was storage duration, not mass or volume. Today if we have a crop-killing drought we can transport crops from other regions. It's expensive and inconvenient but not often life threatening. Even as little as a couple hundred years ago, any society dependent on agriculture would need a crop that could be stored for multiple years to protect against drought.