Abstract：
Teeth play an important role in evolutionary studies due to their good preservation and direct link to diet. The present work makes use of a previously generated database on molar teeth of fossil hominids which consists of cuspal enamel thickness dc, dentin horn angle φ and section width D, all measured on a given histological tooth section. These data are here interpreted with the aid of \"fracture stress\" QF = PF/D2 and geological age t, where PF is the occlusal force needed to cause cusp failure as determined from dc and φ. QF is virtually a constant in non-hominins (\"apes\") while monotonically increasing toward present time in hominins. These two trends intersect at t = ts = 4.5 (0.11) mya, a value similar to other divergence estimates. QF was fitted with a function f(t) which is proportional to (dc/D)2. The monotonic variation of QF and in turn dc/D with t contrasts the more complex behavior generally characterizing other physical entities of fossil hominids. The increase in dc/D in hominins promotes tooth resilience and in turn life span. Finally, it is suggested that PF provides an upper bound to the maximum bite force produced by the jaw structure.
摘要：
牙齿由于其良好的保存和与饮食的直接联系而在进化研究中发挥着重要作用。本工作利用了先前生成的化石原始牙齿磨牙数据库，该数据库由尖牙釉质厚度dc组成，牙本质角角φ和截面宽度D，全部在给定的组织学牙齿切片上测量。这些数据在这里借助“断裂应力”QF=PF/D2和地质年龄t进行解释，其中PF是根据dc和φ确定的引起尖点故障所需的咬合力。QF在非人素（\“猿类\”）中实际上是一个常数，而在人素中朝着当前时间单调增加。这两个趋势在t=ts=4.5(0.11)mya相交，与其他差异估计相似的值。QF用与(dc/D)2成比例的函数f(t)拟合。QF的单调变化以及dc/D与t的单调变化与通常表征化石原始生物的其他物理实体的更复杂的行为形成对比。人类中dc/D的增加促进了牙齿的弹性，进而促进了寿命。最后,建议PF为颌骨结构产生的最大咬合力提供上限。
