Disaffected from the court and shaken out of conventional assumptions about human nature by the Ghost’s revelations, Hamlet begins to think of comparisons with non-human life, beginning with his father as ‘old mole’ (1.5.170). Later he turns to worms, and his attention suggests a willed strategy of existential and ecological discovery, since worms occupied a place diametrically opposite to humans in the traditional hierarchy of life. Renaissance Humanists often used the perceived inferiority of worms and other animals to define human uniqueness. Their gradations of being, by extension, justified human mastery of the earth represented in Hamlet by Claudius’s modernizing transformation of Denmark into a military-industrial state. Adopting a worm-oriented perspective (wryly imagined by conservation ecologist André Voisin in my epigraph), Hamlet begins to question his own conventional Humanist reflexes, such as those on display in his opening soliloquy (e.g. ‘O God, a beast that wants discourse of reason /Would have mourned longer’ [1.2.150–51]). Recent critics have shown how analogies between social behaviour and animals in Hamlet and other Shakespeare plays reflect the rediscovery of classical scepticism towards human superiority by Humanists such as Michel de Montaigne, before René Descartes and other Enlightenment philosophers elevated mind and soul into essential qualities of human nature. As in other areas of ecology and environmentalism discussed in this book, early modern reflections such as Hamlet’s look forward to today’s post-Cartesian and post-human enquiries into human, animal, and cyborgian crossovers. In this chapter I want to align these pre-modern and present-day horizons with the scientific revolution that links them: evolutionary biology’s tracing of human origins to the shared creaturely and genetic life of the planet. Worms will be my trope for Hamlet’s attention to what Giorgio Agamben calls a ‘zone of indeterminacy’ between human and animal life, and what Andreas Höfele identifies as the complex doubleness of similarity and difference that runs through all of Shakespeare’s animal–human relations, beginning with the comic dialogues of Crab and Lance in The Two Gentlemen of Verona.