Recounting his fieldwork in the mountains of Sila in Calabria, southern Italy, and in Brazil’s southeastern uplands, Serra Gaucha, Claudio de Majo combines ecological knowledge derived from the natural sciences with an understanding of the notion of the commons to piece together the environmental history of these two mountain ranges. He argues that the commons, most often seen as an economically motivated notion, can also be seen in relation to metabolic cycles, with mountains uniting the fate of different human populations.