In Patagonia, los puesteros look after other people’s livestock for not very much money, and sometimes go months without seeing anyone else. The landscape in the southernmost part of Chilean Patagonia, often called the End of the World, has a post-apocalyptic quality. At the final stop, so to speak, before Antarctica, the weather is harshly volatile, and in the wilderness surrounding the few small cities and towns, civilization dwindles almost to nothing. Most of the human presence in that region is transient—tourists who marvel at nature and soon depart. But a small number of people do live on the land, in isolated cabins, often going weeks, and sometimes months, without seeing one another, or anyone else. Known as puesteros , they are solitary men employed by landowners to look after ranches and livestock. Because this onerous and not very lucrative work is unappealing to younger generations, the puesteros are an aging breed, with few lined up to replace them.…