Month: September 2022

SOCIAL FUNCTIONS. “Facial displays are generated by mimetic musculature. These displays help regulate and maintain social bonds and organization by cueing individuals to the emotional and behavioral intentions of the sender.” https://lnkd.in/di-WAXE View in LinkedIn

COMPARATIVE ANATOMY. “Recent investigations into mimetic musculature across a broad phylogenetic range of primates have revealed a more complex picture of mimetic musculature morphology than previously thought.” https://lnkd.in/di-WAXE View in LinkedIn

PHYLOGENY. “Our traditional understanding of primate mimetic muscle morphology was firmly entrenched in phylogeny. Muscle number and complexity (high complexity being numerous, small muscles with discrete attachment sites) were conceptualized as ascending along the phylogenetic scale with greatest complexity achieved at Homo sapiens.” https://lnkd.in/di-WAXE View in LinkedIn

ALWAYS MORE COMPLEX. “A new synthesis has recently been formed wherein muscle morphology is understood within the framework of “ecomorphology,” the influences brought by social variables, dietary niche, and primary communication modes along with phylogeny in determining mimetic muscle morphology in any given species. Under this framework, mimetic musculature morphology is influenced heavily by social variables as well as phylogeny.” https://lnkd.in/di-WAXE View in LinkedIn

MIMETIC MUSCLES. “Recent neurobiological evidence also supports the role of socioecological variables in the evolution of primate facial displays and mimetic muscle morphology. Sherwood found that primate species living in large, complex social groups had more facial nerve neurons than species living in small social groups, indicating more potential control over mimetic musculature contraction.” https://lnkd.in/di-WAXE View in LinkedIn

SPECIALIZED TISSUES. “In addition, Sherwood et al. found relatively greater volume of facial nerve nuclei in the great apes (including humans) than in all other Old World primates, suggesting increased differentiation of mimetic muscles and greater use of facial displays in social, visual communication.” https://lnkd.in/di-WAXE View in LinkedIn

BRAIN-MUSCLE AXIS. “Dobson showed that size of the neocortex devoted to social interactions within primates was a significant predictor of facial nerve nuclei volumes in Old World monkeys and apes.” https://lnkd.in/di-WAXE View in LinkedIn

“HUMAN FACES have several derived features. We have everted, deeply colored lips, a relatively high volume of connective tissue deep to the dermis of the face, and our sclera has a large area of white instead of a more darkly colored sclera like other primates.” https://lnkd.in/di-WAXE View in LinkedIn

IMPORTANCE OF LIPS. “Unlike other primates, humans follow eye gaze to determine direction of attention and we uniquely use our lips as articulators in a specialized vocalization called “speech”.” https://lnkd.in/di-WAXE View in LinkedIn

PRIMED FOR SPEED. “Mimetic muscle physiology is also derived in humans relative to other primates. It has long been known that human mimetic muscles are dominated by fast-twitch (type II) myosin fibers.” https://lnkd.in/di-WAXE View in LinkedIn