ABSTRACT
This chapter considers the role of the invisible in human engagement with artifacts. This discussion draws heavily on comparative psychology research on the capacity of chimpanzees for abstract thought in both the social (sense of self) and physical realms, as well as on Tim Ingold’s critique of hylomorphy. The first context in which hominins drew on invisibles was in the use of fracture for stone tool manufacture. The use of fracture by hominins is contrasted with the way in which chimpanzees in the wild crack nuts and chimpanzees in lab experiments have been taught to make stone tools. In both contexts, chimpanzee behavior involves causing failure by loading force—crushing—rather than propagation of fracture. It is argued that fracture, unlike crushing, requires an understanding of an invisible force, as opposed to an appreciation of cause-and-effect relations. Examination of the earliest evidence of stone tool manufacture, including the site of Lokalalei, Kenya, suggests that by 2.5 million years ago, hominins were adept at propagating fracture. The discussion then shifts to the challenge by Paul Bloom, who argues that water can be an artifact. It appears that the extension of artifact status to a liquid is based on containment of the liquid in a vessel, suggesting a certain “stickiness” to artifact status that can extend to materials a vessel contains. Containment is, like fracture, a mechanical force. The role of mechanical forces in the making and functioning of artifacts leads to a consideration of combustion and the prehistory of hominin engagement with fire. The archaeological record from sites including Wonderwerk Cave is discussed to bring out the evidence for a long development of hominin relation with fire. The final section of the chapter turns to the containment of fire and the capture of reflection with mirrors, further strengthening the argument for the role of the intangible in human relationship with artifacts.
