One of the most persistent arguments for modern, mechanized agriculture is that it produces a lot of food per acre, leaving more land for other purposes. I’ve often wondered how solid this argument is, and when a debate broke out recently, I decided to look closer.

It started with a paper from a think tank. The Breakthrough Institute study, called Nature Unbound, argued that, by embracing technology, humanity could shrink its footprint and leave more land for “nature.” (I don’t like this way of defining nature as something apart from humans, but that’s a different issue.)

The Breakthrough people call themselves Ecomodernists and have a long history of pissing off environmentalists. Their paper caught the attention of Guardian columnist George Monbiot, who took the Ecomodernists to task for favoring big industrial farming over small. Monbiot pointed out that in many poor countries, the smaller the farm, the greater its yields. This is true: When people only have a small amount of land to support them, they pour all their efforts into that land and eke more food per square foot than their neighbors with more land.