Evolution of Hearing and Language in Fossil Hominins

Abstract

This chapter outlines the evolution of auditory capacities during the course of human evolution and the implications for understanding when human language may have evolved. These findings are considered within the context of habitat acoustics, the mathematical theory of communication, and the frame/content theory of speech production. Compared to chimpanzees, the auditory pattern in the early hominin taxa Australopithecus and Paranthropus show a heightened sensitivity between 1.0 and 3.5 kHz but a similarly narrow bandwidth of maximum sensitivity. The early hominin auditory pattern may have facilitated short-range communication in open habitats, but their communication pattern apparently did not involve transmission of information beyond that of a chimpanzee. The early hominins likely were restricted to the frame stage of speech production, a phoneme-based, presyntactic form of communication with only limited word formation. In contrast, the Middle Pleistocene Atapuerca Sima de los Huesos (SH) hominins resemble H. sapiens in showing a broad region of heightened sensitivity between 1 and 5 kHz and a wider bandwidth of maximum sensitivity that is extended toward higher frequencies. The wider bandwidth in the Atapuerca (SH) hominins facilitated specialization in the use of complex, short-range vocal communication, including an emphasis on high-frequency consonant production and increased word-formation. The Atapuerca (SH) hominins, then, may have been on the threshold of passing into the frame/content stage of speech production. The evolution of auditory capacities is consistent with the presence of some form of spoken language in the genus Homo prior to the appearance of H. sapiens.