Mandible morphology has yet to yield definitive information on primate diet, probably because of poor understanding of mandibular loading and strain regimes, and overreliance on simple beam models of mandibular mechanics. We used a finite element model of a macaque mandible to test hypotheses about mandibular loading and strain regimes and relate variation in muscle activity during chewing on different foods to variation in strain regimes. The balancing-side corpus is loaded primarily by sagittal shear forces and sagittal bending moments. On the working side, sagittal bending moments, anteroposterior twisting moments, and lateral transverse bending moments all reach similar maxima below the bite point; sagittal shear is the dominant loading regime behind the bite point; and the corpus is twisted such that the mandibular base is inverted. In the symphyseal region, the predominant loading regimes are lateral transverse bending and negative twisting about a mediolateral axis. Compared with grape and dried fruit chewing, nut chewing is associated with larger sagittal and transverse bending moments acting on balancing- and working-side mandibles, larger sagittal shear on the working side, and larger twisting moments about vertical and transverse axes in the symphyseal region. Nut chewing is also associated with higher minimum principal strain magnitudes in the balancing-side posterior ramus; higher sagittal shear strain magnitudes in the working-side buccal alveolar process and the balancing-side oblique line, recessus mandibulae, and endocondylar ridge; and higher transverse shear strains in the symphyseal region, the balancing-side medial prominence, and the balancing-side endocondylar ridge. The largest food-related differences in maximum principal and transverse shear strain magnitudes are in the transverse tori and in the balancing-side medial prominence, extramolar sulcus, oblique line, and endocondylar ridge. Food effects on the strain regime are most salient in areas not traditionally investigated, suggesting that studies seeking dietary effects on mandible morphology might be looking in the wrong places.

下颌骨形态尚未产生关于灵长类动物饮食的确定信息，这可能是因为对下颌骨负荷和应变机制的了解不足，以及过度依赖下颌骨力学的简单梁模型。我们使用猕猴下颌骨的有限元模型来检验关于下颌骨负荷和应变机制的假设，并将咀嚼不同食物时肌肉活动的变化与应变机制的变化联系起来。平衡侧语料库主要由矢状剪力和矢状弯矩加载。在工作侧，矢状弯矩、前后扭转力矩和横向横向弯矩都在咬合点以下达到相似的最大值；矢状切变是咬合点后面的主要加载方式；并且语料库被扭曲使得下颌基部倒置。在联合区域，主要的加载方式是侧向横向弯曲和绕中外侧轴的负扭转。与咀嚼葡萄和干果相比，咀嚼坚果与作用于平衡侧和工作侧下颌骨的矢状和横向弯矩更大、工作侧矢状切变更大以及联合区域垂直轴和横轴扭转力矩更大有关. 咀嚼坚果也与平衡侧后支中较高的最小主应变大小有关；工作侧颊侧牙槽突和平衡侧斜线、下颌隐窝和髁突内矢状面剪切应变幅度较高；和在联合区域更高的横向剪切应变，平衡侧内侧突出，和平衡侧髁突。与食物相关的最大主剪切应变和横向剪切应变大小的最大差异出现在横向环面和平衡侧内侧突起、磨牙外沟、斜线和髁突。食物对应变机制的影响在传统上未被研究的区域最为显着，这表明寻求饮食对下颌骨形态影响的研究可能找错了地方。