Comparative histomorphology of intrinsic vibrissa musculature among primates: Implications for the evolution of sensory ecology and "face touch"

Department of Anatomy and Neurobiology, University of Kentucky, College of Medicine, Lexington, KY 40536.
American Journal of Physical Anthropology (Impact Factor: 2.38). 02/2013; 150(2). DOI: 10.1002/ajpa.22206
Source: PubMed


Macrovibrissae are specialized tactile sensory hairs present in most mammalian orders, used in maxillary mechanoreception or "face touch." Some mammals have highly organized vibrissae and are able to "whisk" them. Movement of vibrissae is influenced by intrinsic vibrissa musculature, striated muscle bands that attach directly to the vibrissa capsule. It is unclear if primates have organized vibrissae or intrinsic vibrissa musculature and it is uncertain if they can move their vibrissae. The present study used histomorphological techniques to compare vibrissae among 19 primates and seven non-primate mammalian taxa. Upper lips of these mammals were sectioned and processed for histochemical analysis. While controlling for phylogenetic effects the following hypotheses were tested: 1) mammals with well-organized vibrissae possess intrinsic vibrissa musculature and 2) intrinsic vibrissa musculature is best developed in nocturnal, arboreal taxa. Our qualitative analyses show that only arboreal, nocturnal prosimians possess intrinsic musculature. Not all taxa that possessed organized vibrissae had intrinsic vibrissa musculature. Phylogenetic comparative analyses revealed a 70% probability that stem mammals, primates, and haplorhines possessed intrinsic vibrissa musculature and well-organized vibrissae. These two traits most likely coevolved according to a discrete phylogenetic analysis. These results indicate that nocturnal, arboreal primates have the potential to more actively use their vibrissae in spatial recognition and navigation tasks than diurnal, more terrestrial species, but there is a clear phylogenetic signal involved in the evolution of primate vibrissae and "face touch." Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.

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    • "comm.). Facial vibrissae (Yoder 1994: character 61) were coded for new taxa according to the presence of vibrissae musculature as reported in Muchlinski et al. (2013). Not all characters have been treated consistently by previous investigators, or were sufficiently described and illustrated so as to enable coding new taxa. "
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    • "These results may reflect their generally low use of facial expression and the use of the mystacial pad in tactile face touch. The mystacial pad of vibrissae in rodents is controlled by both intrinsic musculature and extrinsic musculature, which is composed partly of the mimetic musculature surrounding the lips (D€ orfl, 1982; Muchlinski et al., 2013). The mosaic nature of the current results on mice may be reflective of the specialized use of the OOM and ZM muscle in this group and they may not be the best animal biomedical model for the human face in terms of function. "
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