Adductor Muscle Function and Fiber Type in Macaca and Papio

了解灵长类动物在咀嚼时使用颌部的方式对体质人类学非常重要，因为咀嚼对头骨的形状有重大影响。对头骨形态影响的了解有助于人类学家解释已灭绝灵长类动物的进化史和行为，并理解现存灵长类动物的解剖结构和功能之间的关系。这项研究的目的是确定，对于咀嚼肌肉，纤维类型的变化是否与咀嚼时的肌肉活动有关。本研究将(1)利用组织化学和电泳技术记录成年雄性和雌性猕猴和狒狒咀嚼肌肉中I型（慢）和II型（快）纤维的比例和横截面积，(2)确定纤维类型是否存在性别二型性，(3)确定纤维类型的比例如何与这些动物咀嚼时的肌电活动相关。快速纤维的比例与咀嚼过程中快速产生大咬合力直接相关的假设将被验证。这项研究很重要，因为我们对咀嚼过程中肌肉纤维类型和活动之间的关系知之甚少，它将提供关于头骨结构-功能联系的新信息。此外，该数据将解决关于咀嚼肌纤维类型是否存在性别二态性的争议。如果两性二态性存在，这些数据将为理解两性二态性的功能含义提供基线。

Understanding the ways in which primates use their jaws during chewing is of great importance to physical anthropology because chewing has a major influence on the form of the skull. Knowledge of the influences on skull form helps anthropologists interpret the evolutionary history and behavior of extinct primates and understand the relationship between anatomy and function in living primates. The goal of this study is to determine whether, for the chewing muscles, variation in fiber type is linked to muscle activity during chewing. This research will (1) document the proportion and cross-sectional area of the Type I (slow) and Type II (fast) fibers in the chewing muscles of adult male and female macaques and baboons using histochemistry and electrophoresis, (2) determine whether sexual dimorphism in fiber type is present, and (3) determine how the proportions of fiber types are correlated with electromyographic activity during chewing in these animals. The hypothesis that the proportion of fast fibers is directly related to the rapid production of large bite forces during chewing will be tested. This research is important because little is known about the relation between muscle fiber type and activity during chewing, and it will provide new information about structure-function links in the skull. Furthermore, the data will resolve the controversy over whether there is sexual dimorphism in the fiber type of the chewing muscles. If sexual dimorphism is present, the data will provide a baseline for understanding the functional implications of sexual dimorphism.