The ear ossicles and the evolution of the primate ear: A biomechanical approach

Abstract

From a morphometric viewpoint the variability of human and other primate ear ossicles appears to be suitable for the study of taxonomic and phylogenetic distinction among Primates. It may also be of interest to determine whether they are useful to show differences in the perception of sound from the environment and from conspecifics. The energy transmitted through the ossicles is mantained by the action of different leverages. These modify the action of the ossicles from relatively wide, low energy, movements of the hammer to the smaller, high energy, movements of the stirrup. It seems that the pongid type of ossicle leverage combination saves more energy, possibly with a certain loss of subtle information, but this may be more useful in the wild than decoding voice modulation. The human type leverage, being less demultiplied, may produce a major loss of energy but, perhaps, a more precise conservation of sound information useful for speech communication.