The challenge to anthropocentrism is at the core of critical animal studies, that draws from and contributes to the reflections of posthumanistic thought. By turning their attention from what are usually considered criteria to separate and place in a hierarchy human and nonhuman animals (most prominently, reason and language) to what they have in common, namely their embeddedness and materiality, the animal studies challenges at their very roots the humanistic ideals that dictate what a human beings are, how they look like, what their privileges are. As Cary Wolfe puts it, “underneath them all [human and nonhuman animals] [...] is a shared finitude, a shared ‘passivity’ [...] that runs directly counter to the liberal model of the subject as above all a creature of volition, autonomy, and agency” (Posthumanism 139). By shifting the focus from agency to vulnerability, animal studies seeks to transfigure a principle of exclusion into a common, constitutive ground on which to envision a new way of conceiving the relations among living beings.In this dissertation I analyze texts that reject, each in its own way, the neatness of the distinction between humanness and animality. Their four authors - Federigo Tozzi (1883-1920), Anna Maria Ortese (1914-1998), Primo Levi (1919-1987), and Paolo Volponi (1924-1994) - populate their pages with human characters who look at and interact with nonhuman animals as characters in their own right, and not as mere rhetorical and symbolic props or projections of human feelings, states of mind, or behaviors. The attitude of these writers and of (most of) their characters is born of the intuition of what all animals, human and non human, share - namely their finitude, their vulnerability, the thick, inescapable materiality of their bodies. In this intuition is the germ of a challenge to anthropocentrism through the implicit and sometimes explicit critique of the Cartesian paradigms of mind/body dualism and of the animal-machine, both based on the preeminence of reason as the criterion for the ontological superiority of (a selected few) human animals.