Communicative capacities in Middle Pleistocene humans from the Sierra de Atapuerca in Spain

Abstract

The present study presents new data on the abilities of Homo heidelbergensis to produce and perceive the sounds emitted during modern human spoken language. The pattern of sound power transmission was studied through the outer and middle ears in five individuals from the Sima de los Huesos, four chimpanzees and four modern humans. The results were then used to calculate the occupied bandwidth of the outer and middle ears, an important variable related with communicative capacities. The results demonstrate that the Atapuerca SH hominins were similar to modern humans in this aspect, falling within the lower half of the range of variation, and clearly distinct from chimpanzees. Specifically, the Atapuerca SH hominins show a bandwidth that is slightly displaced and considerably extended to encompass the frequencies that contain relevant acoustic information in human speech, permitting the transmission of a larger amount of information with fewer errors. At the same time, the presence of a complete cervical segment of the spinal column associated with Cranium 5 from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain) makes it possible to estimate the vocal tract proportions in H. heidelbergensis for the first time. The results demonstrate that it is similar to the reconstructed vocal tract in the La Ferrassie 1 Neandertal individual, which has been suggested to have been capable of producing the full range of sounds emitted during modern human spoken language. These results in the Atapuerca (SH) hominins are consistent with other recent suggestions for an ancient origin for human speech capacity.