Supplying European farmers with guano would involve transporting large quantities of excrement across the Atlantic, a project that understandably failed to enthuse shipping companies.

Charles Mann, in his fascinating 1491, on the slow uptake in Europe of the South American innovation of mining for fertilizer from Peru’s 147 guano islands.

Poop jokes notwithstanding, the 19th century guano trade is fascinating, a tale of slavery of the most horrific kind, “guano barons” in Peruo, built on the reality that agriculture was the dominant economic activity in nations of the day, and depleted soils was an ever-present reality. Europe got over its reticence regarding a global shit trade. Guano became a very big deal.