There are many stories about wildmen in medieval Europe, and in this lecture I focus on one particularly strange example from fourteenth-century France. Tristan de Nanteuil recounts the story of a foundling raised by animals in the forest, but describes the forest as a place of organized social relations among the animals and the child, and even imagines that they share a symbolic kinship. The wild boy discovers his human identity in a series of encounters with gendered bodies, and ultimately leaves animal society to take his place in a noble human lineage. In its representations of animality and gendered embodiment, this fictional text offers a perspective on what it means to be human, even as it questions the categories through which human distinction is commonly defined.