Guatelli-Steinberg Debbie, Reid Donald J, Bishop Thomas A
Department of Anthropology, The Ohio State University, Columbus, OH 43210, USA.
J Hum Evol. 2007 Jan;52(1):72-84. doi: 10.1016/j.jhevol.2006.08.001. Epub 2006 Aug 10.
The formation of lateral enamel in Neandertal anterior teeth has been the subject of recent studies. When compared to the anterior teeth of modern humans from diverse regions (Point Hope, Alaska; Newcastle upon Tyne, England; southern Africa), Neandertal anterior teeth appear to fall within the modern human range of variation for lateral enamel formation time. However, the lateral enamel growth curves of Neandertals are more linear than those of these modern human samples. Other researchers have found that the lateral enamel growth curves of Neandertals are more linear than those of Upper Paleolithic and Mesolithic modern humans as well. The statistical significance of this apparent difference between Neandertal and modern human lateral enamel growth curves is analyzed here. The more linear Neandertal enamel growth curves result from the smaller percentage of total perikymata located in the cervical halves of their teeth. The percentage of total perikymata in the cervical halves of teeth is therefore compared between the Neandertal sample (n=56 teeth) and each modern human population sample: Inuit (n=65 teeth), southern African (n=114 teeth), and northern European (n=115 teeth). There are 18 such comparisons (6 tooth types, Neandertals vs. each of the three modern human populations). Eighteen additional comparisons are made among the modern human population samples. Statistically significant differences are found for 16 of the 18 Neandertal vs. modern human comparisons but for only two of the 18 modern human comparisons. Statistical analyses repeated for subsamples of less worn teeth show a similar pattern. Because surface curvature is thought to affect perikymata spacing, we also conducted measurements to assess surface curvature in thirty teeth. Our analysis shows that surface curvature is not a factor in this lateral enamel growth difference between Neandertals and modern humans.
尼安德特人前牙外侧釉质的形成一直是近期研究的主题。与来自不同地区（阿拉斯加的霍普角；英国泰恩河畔纽卡斯尔；南非）的现代人类前牙相比，尼安德特人前牙在外侧釉质形成时间上似乎处于现代人类的变异范围内。然而，尼安德特人的外侧釉质生长曲线比这些现代人类样本的更为线性。其他研究人员还发现，尼安德特人的外侧釉质生长曲线也比旧石器时代晚期和中石器时代的现代人类更为线性。本文分析了尼安德特人和现代人类外侧釉质生长曲线之间这一明显差异的统计学意义。尼安德特人釉质生长曲线更线性是因其牙齿颈部一半区域内的釉面横纹总数占比更小。因此，对尼安德特人样本（n = 56颗牙齿）与每个现代人类群体样本（因纽特人，n = 65颗牙齿；南非人，n = 114颗牙齿；北欧人，n = 115颗牙齿）牙齿颈部一半区域内的釉面横纹总数占比进行了比较。共有18组这样的比较（6种牙齿类型，尼安德特人与三个现代人类群体中的每一个进行比较）。在现代人类群体样本之间又进行了18组比较。在18组尼安德特人与现代人类的比较中，有16组存在统计学显著差异，但在18组现代人类之间的比较中只有两组存在差异。对磨损程度较小的牙齿子样本重复进行统计分析显示出类似的模式。由于表面曲率被认为会影响釉面横纹间距，我们还对30颗牙齿进行了测量以评估表面曲率。我们的分析表明，表面曲率并非尼安德特人和现代人类在外侧釉质生长差异中的一个因素。
