Enamel extension rate patterns in modern human teeth: Two approaches designed to establish an integrated comparative context for fossil primates
Enamel extension rate patterns in modern human teeth: Two approaches designed to establish an integrated comparative context for fossil primates
复制标题
DOI：
10.1016/j.jhevol.2012.05.006
复制
发表时间：
2012-09-01
影响因子：
3.2
通讯作者：
Reid, Donald J.
中科院分区：
文献类型：
--
作者：
Guatelli-Steinberg, Debbie;Floyd, Bruce A.;Reid, Donald J.
釉质延伸率（EER），即成釉细胞分化的速率，决定了牙冠在高度上生长的速度。化石灵长类动物（包括人类）釉质显微结构的研究通常集中在釉质形成时间的物种差异，但他们也开始解决物种水平的变化，在釉质扩展速率。为了提高我们比较灵长类物种之间EER的能力，更好地了解EER在物种内的变化是必要的。使用一个大的和多样化的现代人类组织学样本，我们发现，初始EER和EER的变化模式沿着牙釉质牙本质交界处（EDJ）变化与EDJ长度有关。我们还发现，釉质形成时间的变化与EDJ长度有关，但它独立于初始EER。这些结果表明，EDJ长度的变化在一个物种的样本可以影响种间比较，不仅EERs，但也釉质形成时间。此外，这些结果在种内支持了基于人类物种之间的比较的假设，即EER和冠形成时间可以独立变化（Dean，2009）。在第二种方法中，我们分析了EER的变化，特别是在两个现代人群样本的侧釉，因为这些变化与perikymata的分布。作为内部釉质生长增量的表面表现，perikymata提供了有关化石中釉质生长的有价值的信息来源。我们发现，EER的下降，在侧釉与perikymata密度增加，从第一次到最后形成的侧釉。此外，个体间EER下降程度的变化与其釉质表面沿着的perikymata分布的变化有关。这些后者的研究结果表明，在釉质表面上的perikymata的分布提供了信息的EER下降率在侧釉，至少在现代人类。(C)2012爱思唯尔有限公司保留所有权利。
Enamel extension rates (EERs), the rates at which ameloblasts differentiate, determine how fast tooth crowns grow in height. Studies of fossil primate (including hominin) enamel microstructure usually focus on species differences in enamel formation time, but they have also begun to address species-level variation in enamel extension rates. To improve our ability to compare EERs among primate species, a better understanding how EERs vary within species is necessary. Using a large and diverse modern human histological sample, we find that initial EERs and patterns of EER change along the enamel-dentine junction (EDJ) vary in relation to EDJ length. We also find that enamel formation time varies in relation to EDJ length, but that it does so independently of initial EERs. These results suggest that EDJ length variation within a species sample can affect interspecific comparisons not only of EERs but also of enamel formation times. Additionally, these results lend within-species support to the hypothesis, based on comparisons among hominin species, that EERs and crown formation times can vary independently (Dean, 2009). In a second approach, we analyzed EER changes specifically in the lateral enamel of two modern human population samples as these changes relate to the distribution of perikymata. As surface manifestations of internal enamel growth increments, perikymata provide a valuable source of information about enamel growth in fossils. We find that EER declines in the lateral enamel are associated with an increase in perikymata density from first to last-formed lateral enamel. Moreover, variation in the extent of EER decline among individuals is associated with variation in the distribution of perikymata along their enamel surfaces. These latter findings suggest that the distribution of perikymata on the enamel surface provides information about rates of EER decline in lateral enamel, at least in modern humans. (C) 2012 Elsevier Ltd. All rights reserved.