Agriculture has a dramatic impact on our environment – humans have covered Earth in cropland to feed ourselves or to feed our food. As a result, there has been widespread deforestation, fossil fuel consumption and pollution to feed the planet. And given that human population size is increasing, the problem of feeding everyone and pollution in our environment will only become more pressing. At the same food consumption is converging on a diet higher in meat and empty calories, which puts a strain on arable land and increases greenhouse gas production (see “Humanity is but an anchovy, from a food point of view” for information on human dietary trends and trophic level and “Eating Fewer Resources” for greenhouse gas emissions of meat products).

But is there a way out of it? Tilman and Clark (Tilman and Clark, Nature 515:518-522) investigated whether and how dietary changes…