In multiple entries in his notebooks, Robert Louis Stevenson pauses to consider the failure of scientific language to communicate the abstractions that undergird its theoretical models of natural processes. In failing to make the operations of the physical world speak, materialist discourse suffers from a terminological disorder. His diagnosis is sweeping and acerbic: “Scientific language like most other language is extremely unsatisfactory” (“Note Book” 300). In what follows I will argue that over the course of several key essays of the 1880s and his most famous work of fiction, Strange Case of Dr. Jekyll and Mr. Hyde (1886), Stevenson aims to redress the fundamental abstraction of the most prominent materialist doctrine of his day, Darwinian evolutionary theory, rendering it viscerally communicable in the figure of Hyde, who represents both the individual organism subject to the pervasive modifying forces of speciation and the embodiment, in a single yet fluctuating corporeal entity, of those very forces. Further to this, I will propose that in imagining Hyde’s genesis at the laboratory table (the result of Jekyll’s incursions into nature) and in placing Hyde in symbiosis with the London fog (the admixture of natural forces and human intervention in the form of the burning of fossil fuels), Strange Case can be added to the body of literature that hails the dawning of the Anthropocene, famously defined by Paul Crutzen as the “human-dominated geological epoch supplementing the Holocene” in which the human has become “a major environmental force” (23). The figure of Hyde thus manifests evolutionary forces in all their teeming presence while also harkening the new forms of subjectivity emerging from our catastrophic agency in the present era – one in which the human has become, in the words of Dipesh Chakrabarty, a “geophysical force” (13)..