Global mule numbers have been steadily declining, yet this hybrid and sterile product of mares and asses is not considered endangered, for it is not wild and not even a species. For as long as organic energy regimes prevailed, mules played crucial roles around the world, from southern China to the Alps and across the ocean into the Caribbean, the US South and the Andes. Their intelligence and endurance made possible Iberian colonialism and the Latin American export boom.

Claudia Leal is full professor at the Department of History and Geography at Universidad de los Andes, in Bogota, Colombia, holds a Ph.D. in Geography from the University of California at Berkeley, and is president of the International Consortium of Environmental History Organizations, ICEHO. She is the author of Landscapes of Freedom, Building a Post-emancipation Society in the Rainforests of Western Colombia (2018) and co-editor of A Living Past: Environmental Histories of Modern Latin America (2018). She is finishing a history of Colombian national parks and is researching the history of animals.